ACUS01 KWNS 181621
SWODY1
SPC AC 181619

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1119 AM CDT Wed Jun 18 2025

Valid 181630Z - 191200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING FROM SOUTHEAST MISSOURI EASTWARD ACROSS MUCH OF ILLINOIS/INDIANA...WESTERN OHIO...AND NORTHERN KENTUCKY...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE MID-ATLANTIC REGION...

...SUMMARY...
Severe thunderstorms are expected this afternoon and evening from
parts of southeast Missouri northeastward to the southern Great
Lakes. Scattered to numerous damaging winds, isolated large hail,
and tornadoes all appear possible. Severe thunderstorms with
damaging winds may also develop across parts of the Mid-Atlantic.

...Midwest...
A well-defined shortwave trough is currently over western MO,
tracking rapidly eastward. At the surface, a low is centered over
northeast MO, with a very moist/unstable air mass in place across
much of IL/IN. As large-scale forcing for ascent and strengthening
wind fields overspread the unstable warm sector, supercell
thunderstorms are expected to rapidly develop. All severe hazards,
including a few tornadoes, appear possible through the afternoon as
storms track rapidly northeastward across IL into central/northern
IN. Refer to MCD #1345 for further details. Congealing outflow may
eventually lead to a greater damaging wind threat as storms spread
into lower MI and northern OH.

To the southeast of this early thunderstorm scenario, another zone
of convective initiation is expected from southeast MO into parts of KY/southern IN. These storms are more likely to grow upscale by
early evening, with a risk of damaging winds spreading into southern
OH and central KY. Have expanded the ENH slightly eastward to
better cover this area.

...Mid Atlantic...
Visible satellite imagery shows mostly clear skies and strong
heating occurring over northern/central VA, where a hot/humid
airmass is present. Thunderstorms are expected to develop off the
terrain this afternoon and spread eastward into the DelMarVa region.
Sufficient flow aloft and steep low-level lapse rates will promote
a risk of strong storms capable wind damage. Isolated strong storms
may also affect south-central VA and northern NC later this
afternoon as well. Refer to MCD #1344 for further details.

..Hart/Wendt.. 06/18/2025

$$

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ACUS01 KWNS 181957
SWODY1
SPC AC 181955

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0255 PM CDT Wed Jun 18 2025

Valid 182000Z - 191200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE
MIDWEST AND LOWER GREAT LAKES...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MID
ATLANTIC REGION...

...SUMMARY...
Severe thunderstorms are expected this afternoon and evening from
parts of southeast Missouri northeastward to the southern Great
Lakes. Scattered to numerous damaging winds, isolated large hail,
and tornadoes all appear possible. Severe thunderstorms with
damaging winds may also develop across parts of the Mid-Atlantic.

...20z Update Midwest and Great Lakes...
A well-developed QLCS with multiple embedded bows and recent
measured severe gusts will continue eastward across IN and southern
lower MI this afternoon before reaching western OH this evening.
Moderate buoyancy and enhanced upper-level shear will support
continued storm organization with damaging gusts likely. Embedded
mesovorticies will also pose a risk for a few tornadoes. The main
changes to the outlook where to trim the Enhanced behind the
advancing QLCS.

Farther west near the core of the MCV, several clusters of miniature
supercells have a history of producing tornadoes. This may continue
for a couple more hours as storms near the MCV remain in 100-200
J/kg of low-level buoyancy and strong ambient vorticity. The
eastward extent of this threat is unclear as some overturning behind
the expanding QLCS will likely reduce the threat closer to the IN
border. Additional scattered storms across western MO behind the MCV
may also pose an isolated risk for damaging gusts and small hail
before weakening after dark.

...lower OH Valley...
Across far southeastern MO southern IL and western KY, additional
storm development will continue this afternoon and evening.
Displaced from the enhanced mid-level flow south of the MCV, a mixed
storm mode of supercells and line segments is expected. Large
buoyancy and the tendency for upscale growth suggests damaging winds
are likely. Low-level shear from the VWX/PAH VAD is maximized along
the low-level confluence axis which could also support a couple
tornadoes with the more discrete cells.

...Southern Plains...
A modified outflow boundary may serve as a focus for scattered storm development from the TX Panhandle to southern OK this
afternoon/evening. 2000-3000 J/kg of MLCAPE and ~30 kt of deep-layer
flow will support organized clusters or transient supercells with a
risk for hail and damaging gusts. Have expanded the Slight Risk into southwestern OK where storms appear most likely to develop. See
MCD#1350 for additional short-term information.

..Lyons.. 06/18/2025

.PREV DISCUSSION... /ISSUED 1119 AM CDT Wed Jun 18 2025/

...Midwest...
A well-defined shortwave trough is currently over western MO,
tracking rapidly eastward. At the surface, a low is centered over
northeast MO, with a very moist/unstable air mass in place across
much of IL/IN. As large-scale forcing for ascent and strengthening
wind fields overspread the unstable warm sector, supercell
thunderstorms are expected to rapidly develop. All severe hazards,
including a few tornadoes, appear possible through the afternoon as
storms track rapidly northeastward across IL into central/northern
IN. Refer to MCD #1345 for further details. Congealing outflow may
eventually lead to a greater damaging wind threat as storms spread
into lower MI and northern OH.

To the southeast of this early thunderstorm scenario, another zone
of convective initiation is expected from southeast MO into parts of KY/southern IN. These storms are more likely to grow upscale by
early evening, with a risk of damaging winds spreading into southern
OH and central KY. Have expanded the ENH slightly eastward to
better cover this area.

...Mid Atlantic...
Visible satellite imagery shows mostly clear skies and strong
heating occurring over northern/central VA, where a hot/humid
airmass is present. Thunderstorms are expected to develop off the
terrain this afternoon and spread eastward into the DelMarVa region.
Sufficient flow aloft and steep low-level lapse rates will promote
a risk of strong storms capable wind damage. Isolated strong storms
may also affect south-central VA and northern NC later this
afternoon as well. Refer to MCD #1344 for further details.

$$

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ACUS01 KWNS 190054
SWODY1
SPC AC 190052

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0752 PM CDT Wed Jun 18 2025

Valid 190100Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE LOWER
GREAT LAKES/OHIO VALLEY TO THE SOUTHERN PLAINS...

...SUMMARY...
Severe thunderstorms, with damaging winds, will spread across
portions of the Ohio/Tennessee Valley region this evening. Isolated
severe thunderstorms will also continue across portions of the Red
River region of southern Oklahoma and North Texas.

...01z Update...

Notable mid-level height falls will spread across the lower Great
Lakes/Ohio Valley overnight in response to a short-wave trough that
will advance into MI-IL by the end of the period. Synoptically, LLJ
is strengthening across the OH Valley ahead of the main surface
front that extends from Lake MI-central IL-central MO. While the
primary squall line has surged well ahead of the front into central
OH/KY, scattered convection is gradually increasing along the front
across MO/western IL. This activity may continue to increase as the
boundary surges southeast later tonight. Otherwise, the lead squall
line is expected to propagate into the upper Ohio Valley with an
attendant threat of damaging winds.

Farther southwest into the southern Plains, 00z soundings from both
OUN and FWD exhibit minimal CINH with seasonally high PW values and
strong MLCAPE (>3000 J/kg). Both soundings have adequate deep-layer
shear for organized updrafts, but the Red River corridor should only
experience weak low-level warm advection through the overnight
period. Isolated severe thunderstorms will be the most likely
scenario given the weak forcing along this portion of the boundary.

..Darrow.. 06/19/2025

$$

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ACUS01 KWNS 190553
SWODY1
SPC AC 190552

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1252 AM CDT Thu Jun 19 2025

Valid 191200Z - 201200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE
MIDDLE ATLANTIC...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Severe thunderstorms are expected across much of the Middle Atlantic
region, and to a lesser extent into the Carolinas and over portions
of New England. Severe wind gusts are the primary concern. Isolated
hail and wind threat is expected across the northern Plains into
Minnesota, primarily during the evening/overnight.

...Eastern U.S...

Seasonally strong upper trough is currently located over IL and
should advance into the OH Valley by 18z as stronger 500mb flow
develops across western PA/NY. With time, 50+kt flow should
translate into the Middle Atlantic, coincident/just ahead of the
primary synoptic front. Latest model guidance suggests modest 0-3km
lapse rates will develop by mid day as the boundary layer warms
ahead of the wind shift, especially from the Carolinas into Upstate
NY. In fact, much of the I-95 corridor over the Middle Atlantic will
warm quickly through the 80s to near 90F, effectively removing any
inhibition. As a result, convection should readily develop within a
very moist environment (PWs 1.75-2 inches) characterized by MLCAPE
in excess of 2000 J/kg. Forecast soundings exhibit deep
west-southwesterly flow with 0-6km bulk shear around 30kt. These
profiles favor organized line segments and clusters, and severe wind
gusts will likely be noted with the most robust activity. Convection
should spread off the Middle Atlantic Coast during the evening
hours.

...Northern Plains/Upper MS Valley...

Latest water-vapor imagery depicts a short-wave trough over
southeast BC. This feature will suppress heights across southern
AB/SK early in the period, and a secondary disturbance will eject
across southern SK during the evening. These features are expected
to encourage convective development along the cool side of a
boundary that will be draped from the upper MS Valley-central
ND-southern SK. Low-level warm advection should aid bouts of
elevated convection, but the primary concern is with thunderstorms
that evolve during the early evening. Storms that form over
southeastern SK and southwestern MB will spread southeast toward a
region of increasing low-level warm advection. LLJ is forecast to
increase across eastern SD into southwest MN during the late
evening. Elevated supercells should develop ahead of the Canadian
convection as the LLJ strengthens into the upper Red River Valley.
An MCS may ultimately evolve over the upper MS Valley late in the
period as the LLJ shifts into southeast MN/southwestern WI. Hail and
wind are the primary concern with this activity.

..Darrow/Weinman.. 06/19/2025

$$

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ACUS01 KWNS 191251
SWODY1
SPC AC 191250

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0750 AM CDT Thu Jun 19 2025

Valid 191300Z - 201200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MID-ATLANTIC...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS/UPPER MIDWEST...

...SUMMARY...
Severe thunderstorms are expected across much of the Mid-Atlantic
region today, and to a lesser extent into the Carolinas and over
portions of New England. Severe/damaging wind gusts are the primary
concern. An isolated large hail threat should also develop across
parts of the northern Plains/Upper Midwest, primarily during the evening/overnight hours.

...New England/Mid-Atlantic into North Carolina...
An upper trough will move eastward today from the Great Lakes/OH
Valley across the Mid-Atlantic and Northeast. Seasonably strong
southwesterly mid-level flow around 40-50 kt will accompany this
upper trough passage, and aid in sufficient deep-layer shear for
organized severe thunderstorms across these regions. Recent visible
satellite imagery and surface observations show mostly clear skies
and a moist low-level airmass already in place from the Appalachians
towards the Mid-Atlantic Coast. Ample diurnal heating through this
afternoon should support moderate to locally strong instability
across much of the Mid-Atlantic, with somewhat weaker instability
with northward extent into interior New England.

Current expectations are for multiple cells/clusters to initially
form over the higher terrain of the Appalachians/Blue Ridge
Mountains by early to mid afternoon, and subsequently spread
east-northward to the coast through the afternoon and evening. Given
steepened low-level lapse rates and enhanced low/mid-level flow
associated with the upper trough, scattered to potentially numerous severe/damaging winds will likely be the primary threat with this
convection. The greatest concentration of wind damage should be
focused across parts of the Mid-Atlantic, where the Enhanced Risk
has been maintained with only minor expansion. Otherwise, isolated
hail may also occur with any of the more cellular convection, even
though mid-level lapse rates are not forecast to be overly steep. A
brief tornado or two also appears possible, although low-level winds
will generally be veered to west-southwesterly, limiting 0-1 km SRH.

...Southeast...
A band of thunderstorms is ongoing this morning across parts of the Mid-South/Southeast. This activity has generally remained sub-severe
overnight, and on the southern periphery of an upper trough to the
north. With strong daytime heating of a rather moist low-level
airmass in place to its south and modest deep-layer shear for
updraft organization, there is some opportunity for this convection
to either restrengthen through the afternoon as it spreads
southward, or for redevelopment to occur along its outflow. Have
adjusted the Marginal Risk for damaging winds based on the current
position of ongoing thunderstorms, and their potential to move
southward across parts of the Southeast/central Gulf Coast states
this afternoon/early evening before eventually weakening near the
Gulf Coast.

...Northern Plains/Upper Midwest...
Upper ridging will be maintained today over much of the Rockies and
High Plains. This will tend to suppress convective development for
much of the day. Still, a weak mid-level shortwave trough will move
from western Canada across the Canadian Prairie provinces today,
eventually reaching parts of the northern Plains and Upper Midwest
tonight. This feature, along with increasing low-level warm/moist
advection associated with a strengthening southwesterly low-level
jet across the northern/central Plains this evening, may be
sufficient to aid at least isolated robust thunderstorm development
tonight generally along and north of a surface boundary. Strong
MUCAPE, steep lapse rates aloft, and ample deep-layer shear would
likely support supercells with associated threat for large hail in a
favorable northwesterly mid/upper-level flow regime. There is still
some uncertainty with the placement and overall coverage of these
supercells tonight, but based on latest guidance trends the Slight
Risk has been expanded eastward to include more of central/eastern
MN and western/northern WI. Isolated damaging winds may also occur
if an MCS is able to develop, although this remains highly
uncertain.

...Central Plains...
Moderate to strong instability is forecast to develop this afternoon
across parts of the central Plains along/east of surface lee
troughing. Even though deep-layer shear and forcing aloft will not
be as pronounced as farther north, there appears to be some chance
for high-based convection to develop and pose an isolated hail/wind
threat.

..Gleason/Kerr.. 06/19/2025

$$

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ACUS01 KWNS 191617
SWODY1
SPC AC 191615

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1115 AM CDT Thu Jun 19 2025

Valid 191630Z - 201200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EARLY EVENING ACROSS THE MID-ATLANTIC REGION...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TONIGHT ACROSS THE
NORTHERN PLAINS...

...SUMMARY...
Severe thunderstorms are expected across much of the Mid-Atlantic
region this afternoon and evening, and to a lesser extent into the
Carolinas and over portions of New England. Severe/damaging wind
gusts are the primary concern. An isolated large hail and damaging
wind threat should also develop across parts of the northern
Plains/Upper Midwest, primarily during the evening/overnight hours.

...Eastern US...
A broad and low-amplitude shortwave trough is moving across the
Great Lakes region and Ohio Valley today. Ahead of the trough,
visible satellite imagery shows mostly clear skies from eastern NY
and much of New England southward across the Mid-Atlantic region and
Carolinas. Warm/moist conditions will develop by mid-afternoon,
yielding MLCAPE values of 2000-3000 J/kg across this broad area.
Scattered thunderstorms are expected to develop, with the highest concentrations moving off the higher terrain of PA/VA/NC and
tracking eastward across the ENH risk area.

Forecast soundings along this corridor show 35-50 knot westerly flow
aloft, which will aid in thunderstorm organization and longevity.
Low-level winds are relatively weak/veered, and mid-level lapse
rates are marginal for intense updrafts. This suggests that
damaging wind gusts are the primary concern today.

...ND/MN/WI This Evening/Tonight...
A large upper ridge has become established across the Rockies and
High Plains, with the primary westerlies now extending from MT into
the Dakotas and Great Lakes. Several weak perturbations will top
the ridge today and tonight, and a strengthening low-level jet will
encourage the development of clusters of thunderstorms. One cluster
is expected this evening over parts of MN/WI, with a risk of large
hail.

There is increasing concern for a cluster of storms developing
across southern ND, which may persist through the night into
southern MN. While this scenario is only shown in a handful of 12z
models, have shifted the SLGT farther south for this conditional
risk.

..Hart/Wendt.. 06/19/2025

$$

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ACUS01 KWNS 191952
SWODY1
SPC AC 191951

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0251 PM CDT Thu Jun 19 2025

Valid 192000Z - 201200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER THE
NORTHEAST AND MID ATLANTIC STATES...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
DAKOTAS AND THE UPPER MIDWEST...

...SUMMARY...
Severe thunderstorms are expected across much of the Mid-Atlantic
region through this evening, and to a lesser extent into the
Carolinas and over portions of New England. Severe/damaging wind
gusts are the primary concern. An isolated large hail and damaging
wind threat should also develop across parts of the northern
Plains/Upper Midwest, primarily during the evening/overnight hours.

...20z Update...
The prior outlook remains valid with only minimal changes. Across
parts of the Northeast and Mid Atlantic, several bands/clusters of
strong to severe storms are ongoing ahead of an upper trough over
the upper OH Valley. Moderate buoyancy and deep-layer shear will
continue to support storm organization into line segments and
clusters with an attendant risk for damaging gusts focused across
the Enhanced area. A few weak supercell structures were also noted
over eastern PA into southern New England, where some isolated hail
and a brief tornado will be possible. Convection should continue
into this evening before slowly weakening after sunset.

...Southeast...
In the wake of early morning remnant storms, an advancing outflow
has shifted south across MS/AL and eastern AR. The cluster of storms
on the surging outflow may occasionally produce damaging guts given
the moderate instability. Weak vertical shear should keep the threat
isolated. Have trimmed the MRGL and thunder behind this activity
where additional storms are not expected.

Otherwise, additional storms are possible across the Northern Plains
tonight. See the prior discussion for more info.

..Lyons.. 06/19/2025

.PREV DISCUSSION... /ISSUED 1115 AM CDT Thu Jun 19 2025/

...Eastern US...
A broad and low-amplitude shortwave trough is moving across the
Great Lakes region and Ohio Valley today. Ahead of the trough,
visible satellite imagery shows mostly clear skies from eastern NY
and much of New England southward across the Mid-Atlantic region and
Carolinas. Warm/moist conditions will develop by mid-afternoon,
yielding MLCAPE values of 2000-3000 J/kg across this broad area.
Scattered thunderstorms are expected to develop, with the highest concentrations moving off the higher terrain of PA/VA/NC and
tracking eastward across the ENH risk area.

Forecast soundings along this corridor show 35-50 knot westerly flow
aloft, which will aid in thunderstorm organization and longevity.
Low-level winds are relatively weak/veered, and mid-level lapse
rates are marginal for intense updrafts. This suggests that
damaging wind gusts are the primary concern today.

...ND/MN/WI This Evening/Tonight...
A large upper ridge has become established across the Rockies and
High Plains, with the primary westerlies now extending from MT into
the Dakotas and Great Lakes. Several weak perturbations will top
the ridge today and tonight, and a strengthening low-level jet will
encourage the development of clusters of thunderstorms. One cluster
is expected this evening over parts of MN/WI, with a risk of large
hail.

There is increasing concern for a cluster of storms developing
across southern ND, which may persist through the night into
southern MN. While this scenario is only shown in a handful of 12z
models, have shifted the SLGT farther south for this conditional
risk.

$$

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ACUS01 KWNS 200101
SWODY1
SPC AC 200100

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 PM CDT Thu Jun 19 2025

Valid 200100Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Scattered severe thunderstorms with large to very large hail and
damaging wind gusts are expected across the northern Plains and
upper Mississippi Valley this evening into tonight. Isolated severe
gusts will also be possible from central and eastern North Carolina north-northeastward to New England.

...Northern and Central Plains/Upper Mississippi Valley...
Latest water vapor imagery at mid-levels shows a ridge over the High
Plains, with west-northwesterly flow over much of the central and
northern Plains. At the surface, a 1002 mb low is located over
north-central South Dakota, with a trough extending
south-southwestward into northwest Kansas. An axis of low-level
moisture is analyzed from central Plains northward to near the
surface low and northwestward into western North Dakota. Along this
corridor, the RAP has MLCAPE mostly in the 2000 to 3000 J/kg range.
A severe storm is currently ongoing near the instability max in
southwest North Dakota, with additional isolated severe storms
located in north-central Nebraska and northwest Kansas.

Moderate deep-layer shear is present across much of the central and
northern Plains, which will contribute to an environment supportive
of supercells this evening. A severe threat with more longevity is
expected in the northern Plains. The Bismarck 00Z sounding has a 0-6
km shear around 40 knots, with nearly dry adiabatic low to mid-level
lapse rates. This will support supercells with large to very large
hail, possibly greater than 2 inches in diameter. This, combined
with surface dewpoints in the lower 60s F and substantial
directional shear from the surface to 700 mb, will also support an
isolated tornado threat.

Concerning future convective development, the latest HRRR maintains
a widely spaced coverage for much of the early to mid evening, but
then begins to increases thunderstorm coverage over eastern parts of
the northern Plains late this evening. As the nose of a low-level
jet moves into the eastern Dakotas, a cluster of severe storms is
expected to develop and move eastward into the upper Mississippi
Valley tonight. Supercells with large hail will be possible with
cells than remain discrete. However, linear mode should become
favored, which will likely support an increase in the potential for
severe gusts.

...Eastern States...
A mid-level trough is currently evident on water vapor imagery over
the southern and central Appalachians. Ahead of the trough, a moist
airmass is present from the Carolinas north-northeastward into New
England. The RAP suggests that instability is weak along and ahead
of the surface trough. Short-term model forecasts suggest that
scattered convective coverage will continue over the next few hours.
00Z soundings across the region show moderate deep-layer shear and
have steep lapse rates around 850 mb. This should support an
isolated severe threat over the next couple of hours as low-level
flow gradually increases. Severe wind gusts will be the primary
threat, associated with short bowing line segments.

..Broyles.. 06/20/2025

$$

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ACUS01 KWNS 200601
SWODY1
SPC AC 200600

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Fri Jun 20 2025

Valid 201200Z - 211200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Severe thunderstorms are likely this afternoon into tonight from far
eastern Montana eastward across the northern Plains and into the
upper Mississippi Valley. Tornadoes, with one or two potentially
strong, winds greater than 75 mph, and hailstones greater than 2
inches in diameter will be possible. Marginally severe storms will
also be possible across parts of the northeast New Mexico and
southeast Colorado.

...Northern Plains/Upper Mississippi Valley...
A mid-level shortwave ridge will move eastward today from the
northern Plains into the upper Mississippi Valley. In the wake of
the ridge, a shortwave trough will move quickly east-northeastward
across the northern Plains. At the surface, a low will deepen over
northwestern South Dakota. To the north and northeast of the low, an east-to-west axis of low-level moisture will take shape by
afternoon, along which surface dewpoints will be in the lower to mid
70s F. In response to surface heating, moderate to strong
instability is expected to develop across much of the northern
Plains by afternoon. Convection is first expected to initiate in far
eastern Montana late this afternoon. From this convection,
thunderstorms are forecast to rapidly grow upscale into a
fast-moving linear MCS, with the track of the MCS moving eastward
along a sharp gradient of instability.

RAP late afternoon forecast soundings along the projected track of
the MCS in southeastern North Dakota have MLCAPE around 4500 J/Kg,
with 0-6 km shear near 60 knots. Lapse rates are forecast to be near
8 C/km, and 0-3 km storm relative helicity is forecast to be between
350 and 400 m2/s2. This environment should be favorable for all
hazards, including tornadoes, large hail and wind damage. Tornadoes
will be most likely with supercells and along the leading edge of
bowing segments. A strong tornado or two will be possible. The more
dominant supercells will also be capable of producing hailstones
greater than 2 inches in diameter. A wind-damage threat should exist
along the entire north-south length of the MCS, with a few gusts
over 75 mph possible. The severe threat is expected to continue
through this evening and into the overnight period as the MCS tracks
eastward into the upper Mississippi Valley.

Further southward across much of the Upper Midwest, a few warm-advection-related thunderstorms will be possible early in the
day. Although these cells may be elevated, a marginal severe threat
will be possible, with a potential for isolated severe gusts and
hail.

...Northeast New Mexico/Southeast Colorado...
Southwest mid-level flow will become established across the southern
and central Rockies today. As surface temperatures warm, isolated to
scattered thunderstorms are expected to develop in the higher
terrain. These storms will move into the lower elevations late this
afternoon into this evening. Although instability will be weak,
low-level lapse rates will be very steep, around 9.5 C/Km in some
areas. This could be enough for isolated severe gusts, associated
with low-precipitation cells.

..Broyles/Moore.. 06/20/2025

$$

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ACUS01 KWNS 201256
SWODY1
SPC AC 201254

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0754 AM CDT Fri Jun 20 2025

Valid 201300Z - 211200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Severe thunderstorms are likely this afternoon into tonight from far
eastern Montana eastward across the northern Plains and into the
upper Mississippi Valley. Tornadoes, winds greater than 75 mph, and
hailstones greater than 2 inches in diameter will all be possible.

...Northern Plains/Upper Mississippi Valley...
Showers and thunderstorms have persisted throughout much of the
night into early this morning across central/southern MN, much of IA
and central WI. This activity was supported by a persistent and
moderately strong low-level jet. Expectation is for this cluster to
persist for the next few hours while gradually losing strength amid
a weakening low-level jet.

A very moist airmass exists to the west of this cluster across the
Great Plains. Recent surface analysis places mid 60s dewpoints
through eastern NE, with low 60s reaching into south-central ND.
Surface analysis also places a low near the central SD/NE border
vicinity, with a warm front arcing southeastward from this low
across northeastern NE and western IA before becoming oriented more north-to-south over western MO. Expectation throughout the day is
for this warm front to become better defined as the current surface
low fills and another develops over western SD. This evolution will
be supported as the shortwave trough currently located over the
Great Basin progresses quickly northeastward towards the northern
Plains.

By the mid to late afternoon, a deep surface low will likely be over
western SD with a sharp warm front extending eastward from the low
roughly along the ND/SD border through central MN. Upper 60s to low
70s dewpoints are anticipated along this frontal zone by the late
afternoon, with surface temperatures in the upper 80s to low 90s.
These surface conditions beneath steep mid-level lapse rates will
result in strong to extreme buoyancy, with HREF mean SBCAPE ranging
from 2000 J/kg across western ND to over 4500 J/kg from northeastern
SD into central MN. Thunderstorm development is expected across
eastern MT as the approaching shortwave trough interacts with this
buoyant airmass during the late afternoon. Additionally, surface
convergence could lead to thunderstorm development along the front
farther east from ND into northern MN around the same time. Given
the environment, storms in both of these areas should quickly become
severe, with large to very large hail and tornadoes as the primary
risk. The storms over eastern MT will likely grow upscale into an
organized convective line, although their is still uncertainty
regarding how quickly this occurs. Environmental conditions support
the development of a forward-progressing convective line capable of
strong to severe wind gusts. Some gust over 75 mph are possible. The
potential for line-embedded tornadoes exists as well. The threat for
damaging gusts with this line should continue into Upper Great Lakes
region early Saturday morning.

...Southern/Central High Plains...
Isolated high-based thunderstorms are possible across the region
amid increasing mid-level moisture and glancing ascent from a
shortwave trough farther north. A few strong gusts are possible as
these storms move into the lower elevations this evening.

..Mosier/Leitman.. 06/20/2025

$$

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ACUS01 KWNS 201627
SWODY1
SPC AC 201625

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1125 AM CDT Fri Jun 20 2025

Valid 201630Z - 211200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING
AND TONIGHT FROM EASTERN MONTANA...ACROSS MUCH OF NORTH
DAKOTA...INTO NORTHERN MINNESOTA....

...SUMMARY...
Severe thunderstorms are likely this afternoon into tonight from far
eastern Montana eastward across the northern Plains and into the
upper Mississippi Valley. Tornadoes, winds greater than 75 mph, and
hailstones greater than 2 inches in diameter will all be possible.

...Eastern MT/ND/MN/WI/Upper MI...
No significant changes have been made to the ongoing outlook. Water
vapor imagery shows a deepening upper trough over the northern
Rockies, with a pronounced shortwave trough entering western MT.
Strong lift associated with this trough will overspread eastern MT
and western ND this evening, leading to the development of scattered
supercell thunderstorms in a region of backed/upslope flow to the
north of the surface low. These storms will track eastward through
the evening across ND and eventually grow upscale. Very large hail
and tornadoes will be possible for the first few hours of this
scenario, with an increasing risk of damaging winds with time. An
upgrade to MDT risk was considered, but will maintain ENH due to
diversity of solutions in various model guidance and uncertainty of
corridor of greatest threat.

Farther east, an increasingly strong nocturnal low-level jet will
help rapid thunderstorm development from eastern ND into MN this
evening. Parameters in this area are very favorable for supercells
capable of all severe hazards, including very large hail and
tornadoes. However, late initiation of storms, warm temperatures in
the 850-700mb layer, and rapid storm interactions lend uncertainty
regarding the evolution of this activity. Some 12z guidance
suggests one or more bowing structures evolve out of this cluster,
tracking eastward overnight across MN into WI and Upper MI.

...Western MT...
As the aforementioned shortwave trough moves eastward, scattered
thunderstorms are forecast to develop off the mountains of western
MT. Widespread cloud cover will limit heating/destabilization, but
favorable deep-layer shear may support a few rotating thunderstorms.
Hail could occur in the strongest storms.

...Southeast Lower MI...
A convectively-aided shortwave trough is moving across Lake MI and
western Lower MI. This feature may encourage the development of
scattered thunderstorms this afternoon over southeast Lower MI and
western Lake Erie. These storms could produce gusty winds and hail.

...High Plains...
Full sunshine will lead to steep low-level lapse rates and moderate
CAPE values this afternoon from southwest NE into eastern NM. Deep
mixing will likely result in widely scattered afternoon and evening thunderstorms. This high-based activity will be capable of locally
damaging wind gusts.

..Hart/Squitieri.. 06/20/2025

$$

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ACUS01 KWNS 201955
SWODY1
SPC AC 201954

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0254 PM CDT Fri Jun 20 2025

Valid 202000Z - 211200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM FAR
EASTERN MONTANA...ACROSS MUCH OF NORTH DAKOTA TO NORTHERN
MINNESOTA...

...SUMMARY...
Severe thunderstorms are likely late this afternoon into tonight
from far eastern Montana eastward across the northern Plains and
into the upper Mississippi Valley. Tornadoes, winds greater than 75
mph, and hailstones greater than 2 inches in diameter will all be
possible.

...20z Update Northern Plains...
Confidence in the overall convective evolution of storms expected
today and tonight remains low. Recent observations and CAM guidance
show potential for isolated supercell development within a focused
low-level upslope regime across far eastern MT and southwestern ND.
Current expectations are that isolated storms may develop late this
afternoon and track eastward along the stationary front in eastern
MT and southern ND with a risk for all hazards. Given this
potential, the Slight Risk has been expanded southwestward toward
the MT/WY/SD border where strong heating and low-level convergence
are being maximized near the surface low.

Farther east across ND and western MN, confidence in surface-based
storm initiation remains quite low owing to warm 700 mb temperatures
(13-16 C) and mid-level ridging. However, very strong heating and
mixing (max sfc temps near/exceeding 100 F to the south) may provide
enough ascent for isolated high-based storm development in the early
evening. Should they remain surface-based, they will mature within
an extremely buoyant, and very strongly sheared air mass supportive
of significant severe weather including; very large hail and
tornadoes.

A perhaps more plausible scenario is for scattered storm initiation
from strong low-level warm advection, courtesy of a 40-60 kt
low-level jet, later tonight across central/eastern ND. Likely
elevated, these supercells would pose a risk for large to very large
hail and damaging gusts before growing upscale along the front into
the western Great Lakes overnight. Should this occur, one or more
organized bows with significant damaging winds and a couple
tornadoes is possible. Given the conditional risk and resulting
uncertainties, the outlook remains largely unchanged.

...Florida...
Scattered thunderstorms have developed along typical sea breeze
boundaries across the FL Space Coast to near Tampa Bay. Moderate to
large CAPE (2000-3000 J/kg of MLCAPE) will continue to support
strong pulse updrafts through this evening. Some of these storms
could produce an isolated damaging gust or small hail However, very
weak mid and upper level flow suggests storm organization is
unlikely and the threat will likely remain below 5%.

..Lyons.. 06/20/2025

.PREV DISCUSSION... /ISSUED 1125 AM CDT Fri Jun 20 2025/

...Eastern MT/ND/MN/WI/Upper MI...
No significant changes have been made to the ongoing outlook. Water
vapor imagery shows a deepening upper trough over the northern
Rockies, with a pronounced shortwave trough entering western MT.
Strong lift associated with this trough will overspread eastern MT
and western ND this evening, leading to the development of scattered
supercell thunderstorms in a region of backed/upslope flow to the
north of the surface low. These storms will track eastward through
the evening across ND and eventually grow upscale. Very large hail
and tornadoes will be possible for the first few hours of this
scenario, with an increasing risk of damaging winds with time. An
upgrade to MDT risk was considered, but will maintain ENH due to
diversity of solutions in various model guidance and uncertainty of
corridor of greatest threat.

Farther east, an increasingly strong nocturnal low-level jet will
help rapid thunderstorm development from eastern ND into MN this
evening. Parameters in this area are very favorable for supercells
capable of all severe hazards, including very large hail and
tornadoes. However, late initiation of storms, warm temperatures in
the 850-700mb layer, and rapid storm interactions lend uncertainty
regarding the evolution of this activity. Some 12z guidance
suggests one or more bowing structures evolve out of this cluster,
tracking eastward overnight across MN into WI and Upper MI.

...Western MT...
As the aforementioned shortwave trough moves eastward, scattered
thunderstorms are forecast to develop off the mountains of western
MT. Widespread cloud cover will limit heating/destabilization, but
favorable deep-layer shear may support a few rotating thunderstorms.
Hail could occur in the strongest storms.

...Southeast Lower MI...
A convectively-aided shortwave trough is moving across Lake MI and
western Lower MI. This feature may encourage the development of
scattered thunderstorms this afternoon over southeast Lower MI and
western Lake Erie. These storms could produce gusty winds and hail.

...High Plains...
Full sunshine will lead to steep low-level lapse rates and moderate
CAPE values this afternoon from southwest NE into eastern NM. Deep
mixing will likely result in widely scattered afternoon and evening thunderstorms. This high-based activity will be capable of locally
damaging wind gusts.

$$

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ACUS01 KWNS 210102
SWODY1
SPC AC 210101

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0801 PM CDT Fri Jun 20 2025

Valid 210100Z - 211200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTH DAKOTA AND MINNESOTA...

...SUMMARY...
A significant swath of severe winds is expected this evening and
tonight from the northern Plains eastward into the upper Mississippi
Valley.

...Northern Plains/Upper Mississippi Valley...
Water vapor imagery currently shows a shortwave trough moving
through the northern High Plains. Near the trough, a line of strong
to severe thunderstorms is ongoing across western North Dakota and
far northwestern South Dakota. As these storms move eastward across
the northern Plains this evening, a 60 to 70 knot mid-level jet will
move northeastward through the Dakotas. Lift associated the left
exit region of the jet, combined with a strongly unstable airmass
over the eastern Dakotas and western Minnesota will be favorable for
vigorous convective development. In response, the ongoing storms are
expected to grow upscale into a fast-moving severe MCS. The MCS is
forecast to track eastward across far northern South Dakota, North
Dakota and north-central Minnesota this evening.

At the surface, a 991 mb low will move northeastward across northern
South Dakota this evening. A tongue of very moist air with surface
dewpoints in the lower to mid 70s F will move northward into
southeastern North Dakota and central Minnesota this evening. Within
this moist airmass, strong instability is analyzed by the RAP with
MLCAPE in the 4000 to 5000 J/kg range. The ongoing line of severe
storms will move into this strong instability, and gradually
intensify over the next couple of hours. RAP forecast soundings
along the expected track of the MCS in southeastern North Dakota
this evening have moderate to strong deep-layer shear, long and
looped hodographs and steep mid-level lapse rates. This should be
favorable for supercells with large hail, wind damage and tornadoes.
A strong tornado may occur. Supercell development will be most
likely among cells that remain semi-discrete. However, a line is
expected to become more organized, which will make severe wind gusts
likely along its leading edge. Gusts above 80 mph will be possible
ahead of the more intense parts of the line. A Derecho may develop
across parts of the northern Plains and upper Mississippi Valley
this evening into tonight.

As the MCS moves into central South Dakota over the next few hours,
some short-term model forecasts develop discrete cells further to
the east near the moist axis in the vicinity of the ND-SD-MN triple
point. These storms are forecast to quickly expand in coverage and
move across northwest and north-central Minnesota, ahead of the
approaching MCS. These storms will likely be supercellular, and be
associated with large to very large hail, wind damage and possible
tornadoes.

A consolidation of the two areas of convection will likely take
place late this evening, with the severe MCS continuing to track
eastward across north-central Minnesota. A wind-damage swath is
expected as far east as northern Wisconsin and the western Upper
Peninsula of Michigan. Wind gusts of 85 to 105 mph will be possible
along parts of the MCS track.

...Southern Rockies/Central High Plains...
Water vapor imagery shows southwest flow over much of the
south-central U.S. A subtle shortwave trough appears to be located
in the southern Rockies, where convection has increased in coverage
over the last couple of hours. These storms will continue to move
northeastward into the High Plains this evening. Forecast soundings
from northeast New Mexico into northwest Kansas early this evening
have very steep low to mid-level lapse rates. This will likely
support a marginal threat for severe gusts, as the cells move into
the stronger instability over the High Plains.

..Broyles.. 06/21/2025

$$

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ACUS01 KWNS 210530
SWODY1
SPC AC 210528

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1228 AM CDT Sat Jun 21 2025

Valid 211200Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE GREAT LAKES REGION...

...SUMMARY...
Thunderstorms associated with marginally severe wind gusts and hail
will be possible today from the northern Plains into the Upper
Mississippi Valley and Great Lakes.

...Great Lakes...
A mid-level ridge will move quickly eastward into the Northeast
today, as trailing shortwave trough moves through the Great Lakes.
An MCS with some severe potential will likely be ongoing at the
start of the period in the vicinity of Lake Superior.
Warm-advection-related convection is expected to develop along the
southern edge of the decaying MCS from the Upper Peninsula of
Michigan eastward into northern sections of the Lower Peninsula of
Michigan. As low-level lapse rates steepen during the morning,
isolated damaging wind gusts will be possible with short line
segments. During the afternoon, the brunt of the convection is
forecast to move across southwestern Ontario. The southern edge of
this cluster may move back into the lower 48, affecting parts of New
York during the late afternoon. In central New York, moderate
instability is forecast along with northwest mid-level flow around
50 knots. This should be enough for an isolated wind-damage threat
with the faster-moving short line segments. Hail will also be
possible with the stronger cores.

Further south into parts of northern Pennsylvania, moderate
instability is forecast to develop by afternoon. Due to a lack of
large-scale ascent, convective coverage is expected to be very
isolated. Any cell that can initiate in the higher terrain could
have potential for marginally severe wind gusts.

...Northern Plains/Upper Mississippi Valley...
Anticyclonic southwesterly mid-level flow will be in place today
across much of the north-central U.S. At the surface, a post-frontal
airmass will be in place over much of the northern Plains. Behind
the front, a moist airmass will remain over parts of the Dakotas,
where surface heating should yield moderate instability by
afternoon. Although large-scale ascent will remain weak across most
of the region, pockets of low-level convergence are forecast to
develop within this airmass. This should be enough for isolated
convective initiation during the mid to late afternoon. Marginally
severe wind gusts and hail will be the primary threats.

Further west into the northern High Plains, scattered thunderstorms
are expected to develop during the overnight period, ahead of a
mid-level trough in the northwestern U.S. Although a relatively dry
airmass will be in place, low to mid-level lapse rates will be
steep, and could be enough for a marginal wind-damage threat.

..Broyles/Moore.. 06/21/2025

$$

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ACUS01 KWNS 211238
SWODY1
SPC AC 211236

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0736 AM CDT Sat Jun 21 2025

Valid 211300Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
MICHIGAN AS WELL AS NORTHERN NEW YORK...

...SUMMARY...
Thunderstorms associated with marginally severe wind gusts and hail
will be possible today from Michigan into the Lower Great Lakes
region. Isolated severe storms could also occur across the northern
High Plains and Middle Missouri Valley.

...Great Lakes...
Outflow and remnant convection from last night's severe MCS over the
northern Plains and Upper Midwest is currently moving over Upper MI
and northern MI, while the vorticity maximum is moving through far
northwestern Ontario. General expectation is for the vorticity
maximum to continue eastward through central Ontario and southern
Quebec, with some ascent associated with this system glancing the
Lower Great Lakes region tonight. The low-level jet is expected to
persist, helping to maintain an isolated severe potential with the
activity ongoing on the Upper Great Lakes region for the next few
hours. There is some chance the reintensification occurs along the
outflow later this morning across Lower MI where daytime heating
will contribute to strengthening buoyancy. A Slight Risk was
maintain for this scenario, although warm low/mid-level temperatures
and resultant capping cast doubt to its viability.

Farther east across the Lower Great Lakes region, a few late
afternoon storms are possible as the convection currently over Lower
MI reaches the region. Limited buoyancy should keep any severe
threat with these storm isolated. Additionally, as previously
mentioned, some ascent should glance the Lower Great Lakes vicinity
late tonight/early tomorrow. Forecast soundings depict moderately
steep mid-level lapse rates and unidirectional wind profiles
supportive of a few strong to severe storms.

...Eastern MT into Western ND...
A few elevated storms are currently ongoing across eastern MT,
within a region of strong large-scale ascent ahead of an approaching
shortwave trough. These isolated storms will likely persist this
morning, with a few additional storms possible later this afternoon. Instability will be modest, limited in the overall severe potential,
but strong shear will support organization within an updrafts than
can mature. Isolated hail and/or damaging gusts are the primary
severe risk.

...Central NE/SD/ND into the Upper Midwest...
Surface low currently over central SD is expected to drift slowly
eastward throughout the day, with notable low-level moisture
advection across throughout the warm sector east of this low. This
will allow the airmass to recover from the overnight MCS while also contributing to a sharpening warm-frontal zone. Strong to extreme
buoyancy (i.e. MLCAPE greater from 3000 to 5000 J/kg) is expected by
this evening along this warm front from the ND/SD border vicinity
eastward through central MN into northern WI. Some low-level
convergence is anticipated in this region, but height rises are
anticipated within the large-scale environment. Additionally, warm
mid-level temperatures (i.e. 16 to 17 deg C at 700 mb) are expected,
capping the airmass to deep convection. Given these factors and the
lack of convection within any of the convection-allow guidance, the
Marginal Risk was removed from the majority of the region. The only
exception was from central NE into southeast SD and far southwest MN
where some late night elevated storms capable of hail are possible.

..Mosier/Leitman.. 06/21/2025

$$

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ACUS01 KWNS 211638
SWODY1
SPC AC 211637

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1137 AM CDT Sat Jun 21 2025

Valid 211630Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER NORTHERN
PORTIONS OF NEW YORK AND VERMONT...

...SUMMARY...
Thunderstorms associated with severe wind gusts and hail will be
possible tonight across New York and New England. Isolated severe
storms will also be possible across portions of the Greak Lakes, the
northern High Plains and Middle Missouri Valley.

...Great Lakes...
Strong/intermittently severe thunderstorms continue across the
northern Lower Peninsula of Michigan this morning, associated with
the long-lived severe MCS that moved across the northern
Plains/upper Midwest Friday afternoon and night. Although the
immediate downstream environment is only slowly warming due to the
presence of mid/high-level clouds, some slow destabilization is
occurring. This will maintain at least some continued risk for a
strong/severe storm through early afternoon across northern Lower MI
and adjacent waters of Lake Huron.

Across the MI Upper Peninsula, a warm front is expected to sharpen
across this area, along with rising heights in the wake of the convectively-augmented vorticity maximum now moving through southern
Ontario. Heating of a very moist boundary layer will result in
strong to extreme instability (MLCAPE in excess of 3000 J/kg),
however the presence of a pronounced cap should suppress storms
during the afternoon. As a modest low-level jet strengthens this
evening, isolated elevated severe storms will be possible on the
immediate cool side of the front, within an environment supportive
of organized storms including supercells. Large hail and damaging
winds will be possible.

...NY into Western New England...
Thunderstorms moving across Lake Huron/southwestern Ontario at 16z
will continue east, and most morning CAM guidance suggests storms
will remain west of western NY. Of greater concern will be the
potential for storms to move into northern NY/western New England
late tonight ahead of a southeast-moving cold front, where modest destabilization and strong deep-layer shear will support storm
organization. Morning hi-res guidance supports a loosely organized
linear structure, and perhaps supercells with an attendant risk for
strong winds and severe hail late tonight. The Level 2/Slight Risk
has been expanded east into northern VT based on this expectation.

...Eastern MT into Western ND...
Isolated thunderstorms have weakened over eastern MT this morning,
with additional isolated redevelopment possible this afternoon and
tonight as ascent associated with minor perturbations within
southwest mid-level flow moves across the area. Modest instability
and strong deep-layer shear will support updraft organization and a
risk for severe hail and/or damaging gusts.

...Central NE/SD/ND into the Upper Midwest...
Surface low currently over central SD is expected to move little
this afternoon, with low-level moisture advection throughout the
warm sector east of this low. Air mass recovery/modification
following the overnight MCS is expected, and this will contribute to
a sharpening warm-frontal zone. Strong to extreme buoyancy (i.e.
MLCAPE greater from 3000 to 5000 J/kg) is expected by this evening
along this warm front from the ND/SD border vicinity eastward
through central MN into northern WI. Some low-level convergence is
anticipated in this region, but height rises will occur within the
large-scale environment. Additionally, warm mid-level temperatures
(16 to 17 deg C at 700 mb) are expected, capping the airmass to deep
convection this afternoon. Isolated thunderstorm development will be
possible mainly this evening as a low-level jet strengthens, with a
risk for severe wind and isolated hail.

..Bunting/Jewell.. 06/21/2025

$$

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ACUS01 KWNS 211959
SWODY1
SPC AC 211958

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Sat Jun 21 2025

Valid 212000Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
NORTHERN NEW YORK...VERMONT AND NEW HAMPSHIRE...

...SUMMARY...
Thunderstorms associated with severe wind gusts and hail will be
possible tonight across New York and New England. Isolated severe
storms will also be possible across portions of the Great Lakes, the
northern High Plains and Middle Missouri Valley.

...20z Update...
Minimal changes were made to the prior valid outlook. Thus far,
strong convection across the Great Lakes region has remained on the
Canadian side of the border. Continued heating and weak mid-level
ascent overspreading a trailing composite front/lake breeze boundary
may eventually support scattered storm development over the UP of
Michigan this afternoon/evening. Isolated damaging gusts and some
hail are possible with moderate CAPE and vertical shear. These
storms should grow upscale across the lakes and through southern
Ontario, reaching western New England late tonight as an MCS. This
MCS may pose a risk for damaging gusts late tonight. Have adjusted
the eastern edge of the Slight and Marginal Risk areas for the
latest hi-res guidance.

Otherwise the outlook remains unchanged, see the previous
discussion.

..Lyons.. 06/21/2025

.PREV DISCUSSION... /ISSUED 1149 AM CDT Sat Jun 21 2025/

...Great Lakes...
Strong/intermittently severe thunderstorms continue across the
northern Lower Peninsula of Michigan this morning, associated with
the long-lived severe MCS that moved across the northern
Plains/upper Midwest Friday afternoon and night. Although the
immediate downstream environment is only slowly warming due to the
presence of mid/high-level clouds, some slow destabilization is
occurring. This will maintain at least some continued risk for a
strong/severe storm through early afternoon across northern Lower MI
and adjacent waters of Lake Huron.

Across the MI Upper Peninsula, a warm front is expected to sharpen
across this area, along with rising heights in the wake of the convectively-augmented vorticity maximum now moving through southern
Ontario. Heating of a very moist boundary layer will result in
strong to extreme instability (MLCAPE in excess of 3000 J/kg),
however the presence of a pronounced cap should suppress storms
during the afternoon. As a modest low-level jet strengthens this
evening, isolated elevated severe storms will be possible on the
immediate cool side of the front, within an environment supportive
of organized storms including supercells. Large hail and damaging
winds will be possible.

...NY into Western New England...
Thunderstorms moving across Lake Huron/southwestern Ontario at 16z
will continue east, and most morning CAM guidance suggests storms
will remain west of western NY. Of greater concern will be the
potential for storms to move into northern NY/western New England
late tonight ahead of a southeast-moving cold front, where modest destabilization and strong deep-layer shear will support storm
organization. Morning hi-res guidance supports a loosely organized
linear structure, and perhaps supercells with an attendant risk for
strong winds and severe hail late tonight. The Level 2/Slight Risk
has been expanded east into northern VT based on this expectation.

...Eastern MT into Western ND...
Isolated thunderstorms have weakened over eastern MT this morning,
with additional isolated redevelopment possible this afternoon and
tonight as ascent associated with minor perturbations within
southwest mid-level flow moves across the area. Modest instability
and strong deep-layer shear will support updraft organization and a
risk for severe hail and/or damaging gusts.

...Central NE/SD/ND into the Upper Midwest...
Surface low currently over central SD is expected to move little
this afternoon, with low-level moisture advection throughout the
warm sector east of this low. Air mass recovery/modification
following the overnight MCS is expected, and this will contribute to
a sharpening warm-frontal zone. Strong to extreme buoyancy (i.e.
MLCAPE greater from 3000 to 5000 J/kg) is expected by this evening
along this warm front from the ND/SD border vicinity eastward
through central MN into northern WI. Some low-level convergence is
anticipated in this region, but height rises will occur within the
large-scale environment. Additionally, warm mid-level temperatures
(16 to 17 deg C at 700 mb) are expected, capping the airmass to deep
convection this afternoon. Isolated thunderstorm development will be
possible mainly this evening as a low-level jet strengthens, with a
risk for severe wind and isolated hail.

$$

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ACUS01 KWNS 220103
SWODY1
SPC AC 220101

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0801 PM CDT Sat Jun 21 2025

Valid 220100Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NEW YORK AND NEW ENGLAND...

...SUMMARY...
Thunderstorms associated with severe wind gusts and hail will be
possible tonight across New York and New England. Isolated severe
storms will also be possible across parts of the Great Lakes and the
central to northern Plains.

...Northeast/New York/Great Lakes...
Latest water vapor imagery has a belt of strong anticyclonic flow
located from the upper Mississippi Valley into the Great Lakes and
Northeast. A ridge-riding mid-level shortwave trough is located over
Ontario. At the surface, a moist airmass is in place from New York
into western New England, where surface dewpoints are in the lower
to mid 60s F. The low-level moisture will contribute to continued destabilization across the region, in the form of elevated
instability, this evening into tonight. As the shortwave trough
moves southeastward toward the Northeast, low-level flow will
markedly strengthen. In response, convective coverage is expected to
increase, and a line of thunderstorms appears likely to develop late
this evening. This line is forecast to move southeastward across New
York and western New England from late evening into the overnight
period.

Overnight, RAP forecast soundings ahead of the line in northern New
York have a low-level temperature inversion, with MUCAPE in the 1500
to 2000 J/kg range. Effective shear is forecast to be around 40
knots. This should be favorable for a severe threat. Although much
of the line could be elevated, isolated large hail and severe gusts
will still be possible, mainly with the more intense component of
the line. The line is expected to move through the western New
England and the Hudson River Valley late tonight, approaching
southern New England toward 12Z.

...Central Plains...
Southwest mid-level flow is in place across much of the central
Plains early this evening. At the surface, a moist airmass is
located over much of the High Plains, with surface dewpoints mostly
in the 60s F. In response to low-level warm advection, isolated to
scattered thunderstorms will likely develop along the western edge
of this moist airmass. This convection is expected to move
northeastward across Nebraska and southeastern South Dakota this
evening. In addition to moderate instability, mid-level lapse rates
are very steep. This, combined with moderate deep-layer shear, will
likely support a marginal severe threat. Hail and isolated severe
gusts will be possible.

...Northern High Plains...
A mid-level trough, evident on water vapor imagery, will move
northeastward into the northern High Plains tonight. Ahead of the
trough, a post-frontal airmass is in place with the western edge of
a moist airmass located over the western Dakotas. As large-scale
ascent increases across the northern High Plains later tonight,
scattered thunderstorm development is expected. These storms will
move northeastward across eastern Montana and western North Dakota,
mainly after midnight. Weak to moderate instability, combined with
steep lapse rates and moderate deep-layer shear should support a
marginal severe threat. Hail and a few severe gusts will be
possible.

..Broyles.. 06/22/2025

$$

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ACUS01 KWNS 220601
SWODY1
SPC AC 220600

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Sun Jun 22 2025

Valid 221200Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE GREAT PLAINS...UPPER MISSISSIPPI VALLEY AND NORTHEAST...

...SUMMARY...
Isolated to scattered thunderstorms are expected to develop today
across the northern Plains and Upper Mississippi Valley, some of
which could have large hail, damaging wind gusts and an isolated
tornado threat. Storms associated with severe gusts and hail may
also develop across parts of the Northeast, and in the southern and
central Plains.

...Great Plains/Upper Mississippi Valley...
At mid-levels, southwest flow will be in place today across the
Great Plains, as a trough moves into the northern Rockies. At the
surface, a cold front will advance southeastward across the northern
Plains, as a low moves from the eastern Dakotas into northwest
Minnesota. The boundary will be the focus for convective
development. To the east of the front, a very moist airmass will be
in place with surface dewpoints in the upper 60s to mid 70s F from
the central Plains northeastward into upper Mississippi Valley.
Moderate to strong instability is forecast to develop across much of
the region this afternoon. This, coupled with moderate deep-layer
shear, will be favorable for severe thunderstorm development.

Thunderstorms are expected to first develop across parts of North
Dakota and northwest Minnesota this morning. This activity could be
associated with large hail and isolated severe gusts. As surface
temperatures warm and low-level convergence increases near the
boundary early this afternoon, scattered storms are expected to
develop across parts of the central and northern Plains. These
storms will gradually grow upscale into a organized convective
cluster, moving through eastern South Dakota and western Minnesota.
RAP forecast soundings near Sioux Falls, SD at 21Z have MLCAPE in
the 3000 to 3500 J/kg range with 25 to 30 knots of 0-6 km shear. In
addition, 700-500 mb lapse rates are forecast to be near 9 C/km.
This should be favorable for supercells and/or intense multicells
capable of producing large hail and wind damage. Supercells that
track through the more unstable air to the east of the front could
produce hailstones greater than 2 inches in diameter, and have an
isolated tornado threat. If an intense line segment can organize,
then severe gusts above 70 mph will be possible as well.

Further south-southwest into parts of the southern and central High
Plains, scattered thunderstorms are expected to develop this
afternoon and evening. Surface dewpoints in the 60s F will
contribute to moderate instability. This, combined with very steep
lapse rates from the surface to 700 mb, will likely support a
marginal severe threat. Hail and a few severe gusts will be the
primary threats.

...Northeast...
A line or cluster of thunderstorms will likely be ongoing across the
Northeast at the start of the period. The outflow boundary
associated with this convection is expected to move south and
southwestward into the central Appalachians of Pennsylvania and New
York this morning. Moisture advection will result in a steady
increase in surface dewpoints across much of the region today, with
surface dewpoints increasing into the lower 70s F. As surface
temperatures warm, an axis of strong destabilization is expected to
take shape around midday. Thunderstorms that can develop near the
boundary will move southeastward along the axis of strong
instability. RAP forecast soundings from 18Z to 21Z near the
boundary have MLCAPE around 3000 J/kg range, with 700-500 mb lapse
rates of 7 C/km and moderate deep-layer shear. This should support a
threat for large hail and damaging wind gusts during the afternoon.

..Broyles/Moore.. 06/22/2025

$$

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ACUS01 KWNS 221241
SWODY1
SPC AC 221239

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0739 AM CDT Sun Jun 22 2025

Valid 221300Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE PLAINS...UPPER MISSISSIPPI VALLEY...AND THE NORTHEAST...

...SUMMARY...
Isolated to scattered thunderstorms are expected to develop today
across the northern Plains and Upper Mississippi Valley, some of
which could produce large hail, damaging wind gusts and tornadoes.
Storms associated with severe gusts and hail may also develop across
parts of the Northeast, and in the southern and central Plains.

...Northern/Central Plains into the Upper Midwest...
Widely scattered elevated thunderstorms are currently moving
northeastward across the eastern Dakotas. A few stronger storms are
embedded within these clusters and overall trends suggest increasing
storm coverage is possible as these storms move into more of eastern
ND and northwest/west-central MN. The airmass here is characterized
by very steep mid-level lapse rates (around 8 to 8.5 deg C per km
from 700 to 500 mb per recent mesoanalysis) and moderate deep-layer
vertical shear. These environmental conditions support the potential
for large hail within any more organized updrafts throughout the
morning. See MCD #1400 for additional details.

The strength and extent of these early day storms could impact
thunderstorm chances later. However, the general expectation
supported by all the guidance is that the airmass should easily
recover as the surface low currently over the western SD/NE border
vicinity shifts northeastward across SD and moderate/strong
southerly surface winds persist through the warm sector. By 21Z, the
surface low will likely be over northeast SD with a cold front
extending north-northeastward to a secondary low over northern MN.
Warm mid-level temperatures will cap the airmass until after 21Z,
when isolated development appears possible across northern MN.
Another scenario is for early afternoon initiation behind the front
across ND, supported by a weak vorticity maximum moving out of
western SD. These storms could then gradually move northeastward
into the more unstable airmass farther east. In either case, any
warm-sector development would likely be supercellular and capable of
all severe hazards, including very large hail up to 2" in diameter,
gusts to 75 mph, and tornadoes. The warm front is currently expected
to be just north of the international border, keeping the best
tornado environment in Canada. Upscale growth into a
forward-progressing MCS is possible, but there is currently low
confidence in the overall storm evolution.

Additional development is also possible farther south from
central/eastern NE into eastern SD this evening. This activity
should initially be elevated with hail as the primary risk. A
general northeastward motion is anticipated and there is some chance
for this activity to begin interacting with the frontal zone. If
that occurs, some strong gusts are also possible throughout the
evening.

Lastly, late afternoon thunderstorm development appears probable
across far eastern WY, the NE Panhandle, and southwest SD. High
storm bases coupled with modest buoyancy, deep mixing, and steep
low-level lapse rates will support the potential for strong outflow
with this activity.

...Central/Southern High Plains...
Low-level moisture advection and related airmass destabilization
coupled with low-level convergence along the lee trough is expected
to result in widespread convective initiation from eastern
CO/western KS through eastern NM and into far west TX. Vertical
shear will be modest, likely resulting in a predominantly
outflow-dominant storm structure and the potential for damaging wind
gusts. Some isolated hail is possible as well.

...Northeast...
Remnants of an overnight MCS currently cover much of the Northeast,
with the strongest storms confined to just north of the outflow
along its western periphery. Given the extensive precipitation
ongoing, this outflow will likely shift gradually
south-southwestward throughout the morning. Warm-air advection along
this boundary will weaken throughout the day as upper ridging builds
northward into the region. Even so, low-level convergence along this
boundary will likely continue, and there is some chance for
thunderstorms to persist along this boundary as well. Steepening
mid-level lapse rates and resulting strong buoyancy will support a
conditional risk for severe thunderstorms during the
afternoon/evening in the vicinity of this boundary. Large hail and
damaging gusts are the primary risk with any storms that do develop.

..Mosier/Dean.. 06/22/2025

$$

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ACUS01 KWNS 221637
SWODY1
SPC AC 221636

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1136 AM CDT Sun Jun 22 2025

Valid 221630Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER
MIDWEST TO THE CENTRAL/SOUTHERN HIGH PLAINS AND OVER PORTIONS OF THE NORTHEAST...

...SUMMARY...
Isolated to scattered thunderstorms are expected to develop today
across the northern Plains and Upper Mississippi Valley, some of
which could produce large hail, damaging wind gusts and tornadoes.
Storms associated with severe gusts and hail may also develop across
parts of the Northeast, and in the southern and central Plains.

...Northern/Central Plains into the Upper Midwest...
A warm front extends northeast from a surface low over northern SD
across northern MN and east across the northern Great Lakes. This
warm front should lift north through the day, while a cold front
extends southwest of the surface low into northeast CO.
Thunderstorms over eastern ND/northwest MN have produced near severe
gusts as they continue to move northeast towards the international
border.

Redevelopment of thunderstorms is anticipated towards late afternoon
or early evening across eastern ND/western MN southward into eastern
SD as a weak mid-level perturbation lifts northeast across the area, contributing large-scale ascent and weakening the capping inversion.
These storms will move east/northeast within a strongly unstable air
mass and include a mix of supercell and cluster modes with a risk
for large to very large hail initially, and transition into an
increasing wind threat with time. Tornado potential appears to be
greatest over northern MN, where low-level SRH will be maximized.

The potential for elevated, post-frontal thunderstorm development
across the NE Panhandle will exist later this afternoon/evening,
with storms moving east and posing a risk initially for severe hail.
The severe wind potential will increase with eastward extent as
storms congeal and tap greater surface instability farther east.

...Central/Southern High Plains...
Low-level moisture advection and related airmass destabilization
coupled with low-level convergence along the lee trough is expected
to result in thunderstorm development from eastern CO/western KS
through eastern NM and into far west TX. Vertical shear will be
modest, likely resulting in predominantly outflow-dominant storm
structures and the potential for damaging wind gusts. Some isolated
hail is also possible with the strongest/more persistent updrafts.

...Northeast...
Overall storm intensity along the western flank of outflow from the
long-lived MCS remains sub severe, and have narrowed the Marginal
and Slight Risk areas to along and immediately southwest of the
convective line. Substantial diurnal heating of a very moist air
mass, and 30-40 kts of effective shear, may support some severe
potential as storms move generally southward along the eastern
periphery of the mid-level ridge. Isolated to widely scattered
strong/severe wind gusts will be possible, in addition to isolated
hail reports given seasonably steep mid-level lapse rates.

..Bunting/Squitieri.. 06/22/2025

$$

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ACUS01 KWNS 222002
SWODY1
SPC AC 222000

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Sun Jun 22 2025

Valid 222000Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE MIDWEST
TO PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS....

...SUMMARY...
Isolated to scattered thunderstorms are expected today across the
northern Plains and Upper Mississippi Valley, some of which could
produce large hail, damaging wind gusts and tornadoes. Storms
associated with severe gusts and hail may also develop across parts
of the southern and central Plains, and Northeast.

...20z Update Central/Northern Plains...
Current surface and satellite observations show strong heating
occurring from far eastern WY, into the NE panhandle within a
post-frontal upslope flow regime. As ascent from the primary trough
across the northern Rockies moves overhead, storm initiation appears
likely this afternoon. Weak destabilization, with moderate
deep-layer shear suggests a few supercells are likely with hail and
damaging winds the primary risk. A brief tornado is also possible
with the stronger surface-based supercells given strong low-level
veering. The MRGL and SLGT boundaries have been adjusted westward to
better align with expected storm initiation along the terrain and
stalled front. See MCD#1403 for additional short-term info.

To the north across eastern SD/ND and MN, the severe risk continues
largely as expected. Strong heating ahead of a surface low and warm
front will support scattered storm development this afternoon and
evening. Deep-layer shear will support supercells and clusters
capable of all severe hazards. Storms will continue eastward this
evening and overnight across northern MN with damaging gusts and
hail likely.

...Northeast...
In the wake of an earlier MCS, strong heating remains evident along
a remnant outflow boundary from eastern PA into southwestern NY
state. However, mid-level height rises and subsidence are evident in
visible/WV imagery and will continue to suppress convective
development over much of the region. An isolated storm or two
remains possible along the boundary through late this afternoon, but
more widespread convective coverage is unlikely. Should storms form,
a strong/severe wind gusts will be possible, in addition to sporadic
hail, given seasonably large buoyancy and steep mid-level lapse
rates. With decreased confidence in storm development/coverage, have
opted to remove the SLGT risk and continue with 5% wind/hail
probabilities.

..Lyons.. 06/22/2025

.PREV DISCUSSION... /ISSUED 1136 AM CDT Sun Jun 22 2025/

...Northern/Central Plains into the Upper Midwest...
A warm front extends northeast from a surface low over northern SD
across northern MN and east across the northern Great Lakes. This
warm front should lift north through the day, while a cold front
extends southwest of the surface low into northeast CO.
Thunderstorms over eastern ND/northwest MN have produced near severe
gusts as they continue to move northeast towards the international
border.

Redevelopment of thunderstorms is anticipated towards late afternoon
or early evening across eastern ND/western MN southward into eastern
SD as a weak mid-level perturbation lifts northeast across the area, contributing large-scale ascent and weakening the capping inversion.
These storms will move east/northeast within a strongly unstable air
mass and include a mix of supercell and cluster modes with a risk
for large to very large hail initially, and transition into an
increasing wind threat with time. Tornado potential appears to be
greatest over northern MN, where low-level SRH will be maximized.

The potential for elevated, post-frontal thunderstorm development
across the NE Panhandle will exist later this afternoon/evening,
with storms moving east and posing a risk initially for severe hail.
The severe wind potential will increase with eastward extent as
storms congeal and tap greater surface instability farther east.

...Central/Southern High Plains...
Low-level moisture advection and related airmass destabilization
coupled with low-level convergence along the lee trough is expected
to result in thunderstorm development from eastern CO/western KS
through eastern NM and into far west TX. Vertical shear will be
modest, likely resulting in predominantly outflow-dominant storm
structures and the potential for damaging wind gusts. Some isolated
hail is also possible with the strongest/more persistent updrafts.

...Northeast...
Overall storm intensity along the western flank of outflow from the
long-lived MCS remains sub severe, and have narrowed the Marginal
and Slight Risk areas to along and immediately southwest of the
convective line. Substantial diurnal heating of a very moist air
mass, and 30-40 kts of effective shear, may support some severe
potential as storms move generally southward along the eastern
periphery of the mid-level ridge. Isolated to widely scattered
strong/severe wind gusts will be possible, in addition to isolated
hail reports given seasonably steep mid-level lapse rates.

$$

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ACUS01 KWNS 230038
SWODY1
SPC AC 230036

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0736 PM CDT Sun Jun 22 2025

Valid 230100Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE GREAT PLAINS AND UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Isolated to scattered thunderstorms will continue this evening
across parts of the northern Plains and Upper Mississippi Valley,
some of which could produce large hail, damaging wind gusts and
tornadoes. Storms associated with marginally severe gusts and hail
will also be likely across parts of the southern and central Plains.

...Central and Northern Plains/Upper Mississippi Valley...
A mid-level trough is evident on water vapor imagery over the
northern Rockies, with southwest flow located over the northern
Plains and upper Mississippi Valley. At the surface, a 997 mb low is
located in far southeast North Dakota with a cold front extending
southwestward from the low into eastern South Dakota and central
Nebraska. Surface dewpoints ahead of the front are in the 70s F
across the upper Mississippi Valley, with mostly 60s F located over
parts of the mid Missouri Valley and central Plains. The RAP has
moderate to strong instability analyzed ahead the front, with the
highest instability in north-central Minnesota where MLCAPE is
estimated to be near 4000 J/kg. Scattered thunderstorms are ongoing
near the front in north-central Nebraska, and in the post-frontal
airmass in western Nebraska. This activity is being supported by
subtle shortwave trough moving through the central High Plains. As
low-level flow ramps up this evening, storm coverage is expected to
gradually increase, with the storms moving northeastward into
southern and eastern South Dakota later this evening. Additional
storms appear likely to develop over parts of Minnesota.

Near the front from eastern South Dakota into northwest Minnesota,
RAP forecast soundings suggest that 0-6 km shear will be mostly
between 30 and 40 knots this evening. In addition, 700-500 mb lapse
rates will be near 8 C/km. This environment should support
supercells with large hail. Hailstones greater than 2 inches in
diameter will be possible, mainly over west-central and northern
Minnesota where the strongest instability is analyzed. Some
short-term models also show potential for short intense line
segments. If a line can become organized and remain persistent, the
potential for severe gusts would be pronounced, with wind gusts
above 70 mph possible. A tornado threat will also be likely with
supercells, and bowing line segments.

...Southern and Central High Plains...
Southwest mid-level flow is evident on water vapor imagery over the
southern and central High Plains. At the surface, a 998 mb low is
located in far southwest Nebraska with a moist airmass located to
the south and southeast of the low across much of the central and
southern High Plains. Scattered thunderstorms are ongoing from
eastern New Mexico into the Texas Panhandle. The storms are being
supported by a subtle shortwave trough evident on water vapor
imagery. The storms will continue to move eastward into the stronger instability this evening. The Amarillo 00Z sounding has very steep
low to mid-level lapse rates, with surface dewpoints in the 60s and
about 2000 J/kg of MLCAPE. This should support a threat for isolated
severe gusts this evening. Hail will also be possible with the
stronger cores. The severe threat could expand north-northeastward
into western Kansas as low-level flow increases this evening.

..Broyles.. 06/23/2025

$$

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ACUS01 KWNS 230542
SWODY1
SPC AC 230540

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1240 AM CDT Mon Jun 23 2025

Valid 231200Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS...MID MISSOURI VALLEY...UPPER MISSISSIPPI VALLEY
AND GREAT LAKES...

...SUMMARY...
Storms with isolated severe wind gusts and hail will be possible
today from the southern and central Plains northeastward into the
Great Lakes.

...Central Plains/Mid Missouri Valley/Upper Mississippi Valley/Great
Lakes...
At mid-levels, an anticyclone will remain over much of the eastern
U.S. today, as southwesterly flow remains over the north-central
states. At the surface, a cold front will advance southeastward into
the upper Mississippi and mid Missouri Valleys extending
southwestward into the central Plains. Ahead of the front, surface
dewpoints in the lower 70s F will contribute to moderate
destabilization during the day. As low-level convergence increases
along the front, somewhat widely spaced convection is expected to
initiate. From this convection, several clusters of storms are
expected to move eastward toward an axis of instability. Along and
near the instability axis from northeast Kansas into southern
Wisconsin, deep-layer shear is expected to be modest. However,
low-level lapse rates will become steep in the afternoon, which
could support a potential for isolated severe wind gusts. The severe
threat is expected to be strongly diurnal, with the greatest threat
occurring in the late afternoon and early evening.

...Southern and Central High Plains...
Southwesterly mid-level flow will remain in place today across much
of the south-central U.S. At the surface, a cold front will advance southeastward across the central High Plains. Ahead of the front,
surface dewpoints will be in the 60s F. As surface temperatures warm
during the day, an axis of moderate instability will develop ahead
of the front from eastern New Mexico into southwest Kansas. Although
deep-layer shear is forecast to be relatively weak along this
corridor, the moderate instability combined with steep low to
mid-level lapse rates may be enough for a marginal wind-damage
threat.

...Northern Maine...
At mid-levels, northwest flow will be in place today across northern
New England, where heights will rise substantially. At the surface,
a moist airmass will be located across much of the Northeast, where
surface dewpoints will be mostly from the mid 60s to the lower 70S
F. As surface temperatures warm today, isolated convection
initiation may occur along an axis of low-level convergence in
northern Maine. In addition to the instability, moderate deep-layer
shear will be in place. This could support a marginal wind-damage
threat during the early to mid afternoon.

..Broyles/Moore.. 06/23/2025

$$

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ACUS01 KWNS 231223
SWODY1
SPC AC 231221

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0721 AM CDT Mon Jun 23 2025

Valid 231300Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
PLAINS INTO THE UPPER MS VALLEY AND UPPER GREAT LAKES...

...SUMMARY...
Storms with isolated severe wind gusts and hail will be possible
today from the southern and central Plains northeastward into the
Great Lakes.

...Central Plains into the Upper MS Valley and Upper Great Lakes... Early-morning satellite imagery shows a shortwave trough progressing
through ND and southern SK/MB. Surface analysis places the low
associated with this shortwave over far northwestern ON, with an
attendant cold front arcing from this low through the MN arrowhead
and back through south-central MN, northwest IA,
eastern/south-central NE to another low in northwest KS. Showers and thunderstorms are ongoing along this frontal zone from northeast NE
into southern MN.

Expectation is for the shortwave trough to continue northeastward
through far northwest ON throughout the day, with the primary
surface low also tracking northeastward just ahead of its parent
shortwave. Gradual eastward/southeastward progress of the cold front
is anticipated, although its forward progression will slow with
time, particularly from the Mid MO Valley southwestward into the
southern High Plains. A warm and moist airmass exists ahead of this
front, with temperatures expected to reach the mid 80s to low 90s
amid dewpoints in the upper 60s to low 70s. These conditions will
result in strong buoyancy and little to no convective inhibition
along much of the front by 21Z.

Large-scale forcing for ascent will be negligible, but persist
low-level convergence should be enough to initiate deep convection,
with numerous to widespread thunderstorms anticipated. The stronger
deep-layer vertical shear will lag behind the front across much of
the region, but steep low-level lapse rates and ample moisture
should still result in sporadic damaging gusts. There will be better
overlap between the shear and buoyancy from WI into MI, and there is
some chance for one or more forward-propagating line segments in
this area. Some isolated hail is possible within the more robust
early-stage storms. Storm mergers could also result in updrafts
briefly becoming strong enough to produce hail.

...Southern and Central High Plains...
Numerous thunderstorms are expected to develop during the afternoon
amid persistent low-level convergence within the warm, moist, and
weakly sheared airmass over the region. The lack of stronger shear
will result in largely outflow-dominant storm structures. Given the
high cloud bases and steep low-level lapse rates, damaging gusts are
possible with the stronger storms.

...Northern ME...
A convectively augmented vorticity maximum currently over
northeastern ON is forecast progress eastward through southern QC
and into the Canadian Maritimes during the period. Showers and
thunderstorms will accompany this vorticity max, with a few stronger
storms potentially glancing northern ME this evening. Moderately low
to mid-level westerly flow will support the threat for some damaging
gusts as these storms move through the region.

...Southeast...
Scattered to numerous diurnally driven thunderstorm are expected
across the region today. Shear will be weak, with a multicellular
pulse mode anticipated. Given the ample moisture and likelihood of
storm interactions, a few strong, water-loaded downbursts are
possible. Limited coverage precludes the need for any severe
probabilities.

..Mosier/Leitman.. 06/23/2025

$$

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ACUS01 KWNS 231624
SWODY1
SPC AC 231622

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1122 AM CDT Mon Jun 23 2025

Valid 231630Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
THROUGH LATE EVENING FROM THE CENTRAL PLAINS TO THE UPPER GREAT
LAKES...

...SUMMARY...
Storms with occasional damaging outflow gusts and marginally severe
hail will be possible today from the southern and central Plains
northeastward into the Great Lakes.

...Upper Great Lakes to the Plains this afternoon/evening...
A surface cold front will make slow southeastward progress from WI
to IA and KS, in the wake of a primary shortwave trough moving over
western ON. Surface heating is ongoing ahead of the front, where boundary-layer dewpoints range from the upper 60s to lower 70s
beneath midlevel lapse rates of 7-8 C/km, which will drive MLCAPE of
2000-3000 J/kg. Convective inhibition will likewise weaken by
early-mid afternoon, when thunderstorm development is likely along
the front and differential heating zone in the SLGT risk corridor.
Deep-layer flow will be a little stronger toward WI in closer
proximity to the main belt of westerlies, where a mix clusters/line
segments and transient supercell structures will be possible. The
primary severe threat will be damaging outflow winds (60-70 mph)
from roughly 20z-03z, though isolated large hail of 1-1.5 inches in
diameter may also occur with the strongest storms.

More loosely organized storm clusters are expected this afternoon
through this evening into the southern High Plains, where
thermodynamic profiles will favor isolated severe downbursts.

...Northern Maine later this evening...
Around the northern periphery of a closed midlevel high over the
Appalachians, a series of embedded speed maxima will move over ON/QC
through tonight. Boundary-layer dewpoints in the 60s beneath
midlevel lapse rates near 7 C/km, in combination with daytime
heating, will boost MLCAPE to 1500-2000 J/kg with minimal convective
inhibition by late afternoon. Thunderstorm development is expected
upstream across QC in association with an embedded speed max/surface
wave, and this convection will approach northern ME by late
evening/early tonight. Though buoyancy will slowly weaken with the
loss of daytime heating, low-level hodograph curvature and
deep-layer westerly shear should be sufficient for an organized
storm cluster to reach ME before weakening overnight. Isolated
damaging winds will be the main threat with these storms.

..Thompson/Squitieri.. 06/23/2025

$$

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ACUS01 KWNS 231956
SWODY1
SPC AC 231954

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0254 PM CDT Mon Jun 23 2025

Valid 232000Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
THROUGH LATE EVENING FROM THE CENTRAL PLAINS TO THE UPPER GREAT
LAKES...

...SUMMARY...
Storms with occasional damaging outflow gusts and marginally severe
hail will be possible today from the southern and central Plains
northeastward into the Great Lakes.

...20z Update...
Marginal hail and tornado probabilities were introduced across
western Maine with this update. CAM guidance suggests supercells
moving out of southern Quebec may track into western Maine. The
moist and unstable environment across this region would be
supportive of hail, wind, and perhaps a tornado as 850 mb flow
increases through the evening.

Otherwise, the forecast remains on track with no updates needed. See
previous discussion for more information.

..Thornton.. 06/23/2025

.PREV DISCUSSION... /ISSUED 1122 AM CDT Mon Jun 23 2025/

...Upper Great Lakes to the Plains this afternoon/evening...
A surface cold front will make slow southeastward progress from WI
to IA and KS, in the wake of a primary shortwave trough moving over
western ON. Surface heating is ongoing ahead of the front, where boundary-layer dewpoints range from the upper 60s to lower 70s
beneath midlevel lapse rates of 7-8 C/km, which will drive MLCAPE of
2000-3000 J/kg. Convective inhibition will likewise weaken by
early-mid afternoon, when thunderstorm development is likely along
the front and differential heating zone in the SLGT risk corridor.
Deep-layer flow will be a little stronger toward WI in closer
proximity to the main belt of westerlies, where a mix clusters/line
segments and transient supercell structures will be possible. The
primary severe threat will be damaging outflow winds (60-70 mph)
from roughly 20z-03z, though isolated large hail of 1-1.5 inches in
diameter may also occur with the strongest storms.

More loosely organized storm clusters are expected this afternoon
through this evening into the southern High Plains, where
thermodynamic profiles will favor isolated severe downbursts.

...Northern Maine later this evening...
Around the northern periphery of a closed midlevel high over the
Appalachians, a series of embedded speed maxima will move over ON/QC
through tonight. Boundary-layer dewpoints in the 60s beneath
midlevel lapse rates near 7 C/km, in combination with daytime
heating, will boost MLCAPE to 1500-2000 J/kg with minimal convective
inhibition by late afternoon. Thunderstorm development is expected
upstream across QC in association with an embedded speed max/surface
wave, and this convection will approach northern ME by late
evening/early tonight. Though buoyancy will slowly weaken with the
loss of daytime heating, low-level hodograph curvature and
deep-layer westerly shear should be sufficient for an organized
storm cluster to reach ME before weakening overnight. Isolated
damaging winds will be the main threat with these storms.

$$

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ACUS01 KWNS 240041
SWODY1
SPC AC 240039

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0739 PM CDT Mon Jun 23 2025

Valid 240100Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE LOWER TO MID MISSOURI VALLEY NORTHEASTWARD INTO THE GREAT
LAKES...

...SUMMARY...
Isolated severe wind gusts will be possible this evening from the
southern and central Plains northeastward into the Great Lakes. A
few severe gusts will also be possible in parts of northern Maine.

...Great Lakes/Mid to Upper Mississippi Valley/Lower to Mid Missouri
Valley/ Southern and Central Plains...
A large mid-level anticyclone is in place over much of the eastern
U.S. today, with southwest mid-level flow over the central states.
At the surface, a cold front is located from north-central Kansas
northeastward to southern Wisconsin.. Scattered thunderstorms are
ongoing near the front. Surface dewpoints ahead of the front are
mostly in the 70s F, which is contributing to a
southwest-to-northeast corridor of moderate instability. The RAP
currently is estimating MLCAPE along this corridor in the 2000 to
3500 J/kg range. Along the instability axis, RAP forecast soundings
and regional 00Z soundings suggest that 0-3 km lapse rates are in
the 7 to 7.5 C/km range. This should support a potential for
isolated severe wind gusts, associated with the more intense
multicell line segments. The severe threat is expected to persist
for a few more hours.

Further southwest into the southern and central High Plains,
scattered thunderstorms are ongoing. A moist airmass is present
across much of the region, with surface dewpoints generally in the
60s F. The latest RAP has MLCAPE in the 1000 to 2000 J/kg range in
most areas. This, combined with steep low to mid-level lapse rates,
will support a marginal threat for severe gusts early this evening.

...Northern Maine...
On water vapor imagery, flow is west-northwesterly across much of
the Northeast, with a subtle shortwave trough moving through the
flow. Associated with the trough, a line of thunderstorms is ongoing
in southern Quebec. This line will move east-southeastward across
central and northern Maine this evening. Ahead of the line, surface
dewpoints are in the upper 60s and lower 70s F, which is
contributing to weak instability. In addition, RAP forecast
soundings across northern Maine early this evening, have some
directional shear in the low-levels, with 25 to 35 knots of
mid-level flow. This may be enough for a few marginally severe wind
gusts along the leading edge of the line during the early to mid
evening.

..Broyles.. 06/24/2025

$$

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ACUS01 KWNS 240535
SWODY1
SPC AC 240533

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1233 AM CDT Tue Jun 24 2025

Valid 241200Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL AND NORTHERN HIGH PLAINS...

...SUMMARY...
Storms associated with very large hail and severe wind gusts will be
likely this afternoon and evening in parts of the central and
northern High Plains. Marginally severe storms will be possible this
afternoon from part of the central and northern Plains eastward into
the Northeast.

...Central and Northern High Plains...
A mid-level anticyclone will remain in place today across much of
the southeastern third of the nation, as west-northwesterly
mid-level flow continues from the north-central U.S. into the Great
Lakes. At the surface, a post-frontal airmass will be located over
the central and northern High Plains, where surface dewpoints will
be mostly from the mid 50s to the mid 60s F. As surface temperatures
warm during the day, moderate instability will develop across parts
of the region, and scattered convection will initiate in the higher
terrain. These storms will move eastward into the lower elevations
of the High Plains this afternoon.

RAP forecast soundings from eastern Wyoming into northeastern
Colorado at 21Z have 40 to 50 knots of deep-layer shear, with
700-500 mb lapse rates around 8 C/Km. This environment will support
the development of supercells with large hail. Hailstones of greater
than 2 inches in diameter will be possible with supercells that
become particularly intense. In areas where convective coverage is
greatest, the cells could congeal into short line segments capable
of severe gusts. The severe threat should be greatest from late
afternoon to mid evening.

....Central and Northern Plains/Mid to Upper Mississippi
Valley/Lower Great Lakes/Northeast...
The northern edge of a mid-level anticyclone will remain from the
mid Mississippi Valley east-northeastward into the central
Appalachians today. To the north of the anticyclone,
west-southwesterly mid-level flow will be in place. At the surface,
a front will be positioned from the central Plains
east-northeastward into the lower Great Lakes and Northeast. Near
and to the south of the front, surface dewpoints from the mid 60s to
the lower 70s F will contribute to the development of moderate
instability by afternoon. This, along with increasing low-level
convergence near the front, will result in scattered convective
initiation. Several clusters or line segments are expected to
develop and move eastward into the stronger instability. Although
deep-layer shear will remain on the marginal side for organized
storms, low-level lapse rates will become steep in the mid to late
afternoon. This could support a marginal wind-damage threat with the
stronger multicell line segments in areas that heat up the most.

..Broyles/Moore.. 06/24/2025

$$

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ACUS01 KWNS 241239
SWODY1
SPC AC 241238

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0738 AM CDT Tue Jun 24 2025

Valid 241300Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN AND CENTRAL HIGH PLAINS...

...SUMMARY...
Storms associated with very large hail and severe wind gusts will be
likely this afternoon and evening in parts of the central and
northern High Plains. Marginally severe storms will be possible this
afternoon from part of the central and northern Plains eastward into
the Northeast.

...Synopsis...
Early morning satellite imagery shows an expansive upper ridge over
much of the eastern CONUS, and upper troughing across the Great
Basin vicinity. A northern-stream shortwave trough currently over SK
is forecast to progress quickly eastward through MB and ON, leading
to some dampening of the eastern CONUS ridge. Several convectively
augmented vorticity maxima are also expected to move through the
northern and central High Plains ahead of the more substantial
shortwave trough moving across the Great Basin. This evolution will
lead to some dampening of the northwestern periphery of this ridge
as well.

Like the upper pattern, the surface pattern is currently dominated
by eastern CONUS ridging, with an ill-defined frontal zone between
the warm and moist airmass under the ridge and a more continental
airmass across the northern Plains and Upper MS Valley. Recent
surface analysis places a low over western KS with a stationary
boundary extending northeastward from this low to another low over
WI. A more progressive cold front extends northeastward from the WI
low through central ON. The moist airmass (i.e. dewpoints in the
70s) south of this boundary will destabilize with daytime heating,
and scattered thunderstorm development is anticipated amid modest
low-level convergence during the afternoon from the central Plains
through the Great Lakes region into the Northeast. Vertical shear
will be weak, limiting storm strength/organization and contributing
to an outflow-dominant storm mode. Damaging gusts will be possible
with any of the stronger line segments. Greater severe potential is
expected across the northern and central High Plains (discussed
below).

...Northern/Central High Plains...
Post-frontal southeasterly upslope flow is anticipated across the
region today, helping to offset diurnal mixing and keep dewpoints in
the upper 50s/low 60s this afternoon. The increased low-level
moisture and strong heating will foster airmass destabilization by
the early afternoon, with scattered to numerous thunderstorm
expected. Initiation is expected over the higher terrain before then
moving northeastward into the lower elevations. Vertical shear will
be strong enough to support supercells initially capable of
producing large to very large hail. A trend towards more
outflow-dominant structures is anticipated with time, with one or
more line segments capable of strong to severe gusts developing.
This outflow-dominant character is forecast to limit the tornado
threat, but a locally enhanced threat may exist from southeast WY
into the southern NE Panhandle and far northeast CO where the best
overlap between low-level moisture and southeasterly surface winds
is expected.

...Southern Rockies...
Increasing low to mid-level moisture will support numerous to
widespread thunderstorms across the southern Rockies today. Very
shear will be weak, promoting a mostly disorganized multicellular
mode.

..Mosier/Leitman.. 06/24/2025

$$

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ACUS01 KWNS 241613
SWODY1
SPC AC 241611

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1111 AM CDT Tue Jun 24 2025

Valid 241630Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING OVER THE CENTRAL HIGH PLAINS...

...SUMMARY...
Storms associated with large hail and severe wind gusts will be
likely this afternoon and evening in parts of the central and
northern High Plains. Marginally severe storms will be possible this
afternoon from part of the central Plains eastward into the
Northeast - and in the mountains of Tennessee, North Carolina, and
southern Virginia.

...High Plains...
Deep east-southeasterly upslope flow is present this morning across
the High Plains of WY/CO. Surface dewpoints in the mid-upper 50s,
coupled with thinning clouds and strong afternoon heating will yield
a corridor of moderate CAPE across much of eastern WY and northeast/east-central CO. Thunderstorms are expected to initiate
off the higher terrain by early afternoon and spread northeastward
with risk of large hail and damaging wind gusts for several hours.

...Lower MI/Northern IN/OH...
A weak surface cold front extends across southern Lower MI today,
with dewpoints in the low-mid 70s to the south of the boundary.
This air mass is heating rapidly and should become very unstable,
leading to scattered afternoon thunderstorms. Hot surface
temperatures and steep low-level lapse rates will promote
gusty/damaging wind gusts in the strongest cells.

...TN/NC/VA Mountains...
A hot and humid surface air mass is in place today over the
mountains of east TN, western NC, and southern VA. This should lead
to widely scattered thunderstorm development. Winds aloft are weak,
but steep low-mid level lapse rates, ample dry air aloft, and
considerable CAPE will promote strong downdrafts and small hail in
the strongest cells.

..Hart/Squitieri.. 06/24/2025

$$

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ACUS01 KWNS 241959
SWODY1
SPC AC 241957

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0257 PM CDT Tue Jun 24 2025

Valid 242000Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING OVER THE CENTRAL HIGH PLAINS AND SEPARATELY OVER PARTS OF
THE NORTHEAST...

...SUMMARY...
Large hail and severe wind gusts are likely this afternoon and
evening in parts of the central and northern High Plains. Damaging
wind gusts are also expected across parts of northern New York into
Vermont this afternoon.

...20Z Update...
The primary change with this update was the addition of a Slight
Risk (driven by 15-percent wind probabilities) over parts of
northern NY into northern VT. Here, temperatures have warmed into
the upper 80s/lower 90s amid upper 60s/lower 70s dewpoints --
contributing to moderate-strong surface-based instability. As storms
continue tracking/developing eastward into northern NY, around 40 kt
of deep-layer shear accompanying a glancing midlevel speed maximum
should promote several small/loosely organized storm clusters
capable of producing damaging wind gusts through this afternoon. For
details on the severe risk in the central High Plains, reference
Severe Thunderstorm Watch 458.

..Weinman.. 06/24/2025

.PREV DISCUSSION... /ISSUED 1111 AM CDT Tue Jun 24 2025/

...High Plains...
Deep east-southeasterly upslope flow is present this morning across
the High Plains of WY/CO. Surface dewpoints in the mid-upper 50s,
coupled with thinning clouds and strong afternoon heating will yield
a corridor of moderate CAPE across much of eastern WY and northeast/east-central CO. Thunderstorms are expected to initiate
off the higher terrain by early afternoon and spread northeastward
with risk of large hail and damaging wind gusts for several hours.

...Lower MI/Northern IN/OH...
A weak surface cold front extends across southern Lower MI today,
with dewpoints in the low-mid 70s to the south of the boundary.
This air mass is heating rapidly and should become very unstable,
leading to scattered afternoon thunderstorms. Hot surface
temperatures and steep low-level lapse rates will promote
gusty/damaging wind gusts in the strongest cells.

...TN/NC/VA Mountains...
A hot and humid surface air mass is in place today over the
mountains of east TN, western NC, and southern VA. This should lead
to widely scattered thunderstorm development. Winds aloft are weak,
but steep low-mid level lapse rates, ample dry air aloft, and
considerable CAPE will promote strong downdrafts and small hail in
the strongest cells.

$$

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ACUS01 KWNS 250059
SWODY1
SPC AC 250057

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0757 PM CDT Tue Jun 24 2025

Valid 250100Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL AND NORTHERN PLAINS...AND IN PARTS OF THE NORTHEAST...

...SUMMARY...
Large hail and severe wind gusts will be possible this evening in
parts of the central and northern High Plains. Isolated damaging
wind gusts will also be possible across parts of northern New York
into Vermont and New Hampshire early this evening.

...Central and Northern High Plains...
According to water vapor imagery, mid-level anticyclonic
southwesterly flow is currently present across much of the
north-central U.S. At the surface, a 1012 mb low is analyzed over
far eastern Colorado, with an upslope flow regime located over much
of the central and northern High Plains. Surface dewpoints within
the post-frontal airmass are mostly in the 60s F, which is
contributing to moderate instability over much of the region.
Scattered thunderstorms are ongoing along the western edge of the
moist airmass from eastern Colorado into southwest Nebraska.
Isolated storms are ongoing near the instability axis in central
Wyoming. As low-level flow increases early this evening, convective
coverage will likely be maintained as the storms move northeastward
into the lower elevations.

The most favorable environment for supercells appears to be in
central Wyoming. RAP forecast to the northwest of Casper, WY early
this evening have 0-6 km shear around 60 knots with 700-500 mb lapse
rates near 8.5 C/km. This may support a threat for isolated large
hail. Further to the southeast into parts of northeast Colorado and
southwest Nebraska, a cluster of strong to severe storms is ongoing.
Although a supercell will be possible within this cluster, the more
common storm type should be multicellular. This storm mode will
favorable severe gusts as the primary threat, especially with short
intense line segments.

Further to the east across parts of the central Plains, lower
Missouri Valley and southern Great Lakes, scattered thunderstorms
are ongoing near a front. Surface dewpoints in the upper 60s and
lower 70s F, combined with moderate instability and steep low-level
lapse rates, may be enough for marginally severe gusts early this
evening.

...Northern New York/Vermont, New Hampshire...
Mid-level westerly flow is currently located over much of the
Northeast. At the surface, a moist airmass is present across much of
the region with surface dewpoints mostly in the upper 60s to lower
70s F. An axis of moderate instability is analyzed from central New
York into western New England. To the north of the instability axis,
isolated to scattered storms are ongoing. In the vicinity of the
ongoing convection, the RAP has 20 to 25 knots of low-level flow,
0-3 km lapse rates near 7.5 C/km and moderate deep-layer shear. This
may be enough for severe wind gusts early this evening, associated
with the stronger multicells.

..Broyles.. 06/25/2025

$$

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ACUS01 KWNS 250551
SWODY1
SPC AC 250550

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1250 AM CDT Wed Jun 25 2025

Valid 251200Z - 261200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CAROLINAS...SOUTHEAST...AND MID MISSOURI VALLEY...

...SUMMARY...
Severe wind gusts are possible from parts of the Carolinas into the
Southeast, with widely scattered strong to severe storms possible
from the northern High Plains eastward to the Mid Atlantic.

...Carolinas/Southeast...
A mid-level anticyclone will remain over the southeastern U.S.
today. Beneath this large area of high pressure, a very moist
airmass will be in place from the southern and central Appalachians
to the Eastern Seaboard. Surface dewpoints will be mostly from the
upper 60s to the mid 70s F. As surface temperatures warm today,
moderate to strong instability is expected over much of this moist
airmass. Model forecasts suggest that low-level convergence will
lead to convective development over far southern Virginia and
northern North Carolina around midday. This convection is expected
to increase in coverage, moving south to southwestward across the
Carolinas. A line is expected to gradually organize during the
afternoon.

At 21Z, RAP forecast soundings along the instability axis in the
Carolinas, suggest that MLCAPE will peak in the 3000 to 4000 J/kg
range, and that a substantial amount of DCAPE will exist. 0-3 km
lapse rates are forecast to reach the 8 to 8.5 C/km range. In
addition, forecast soundings have inverted-V profiles, with 0-6 km
shear in the 15 to 20 knot range. This should be favorable for
damaging wind gusts, associated with pulse storms and multicells. If
a line segment can organize ahead of a cold pool, then the
wind-damage potential could cover a somewhat large area from the
Carolinas southwestward into the eastern Gulf Coast states.

...Central Plains/Mid Missouri and Mid to Upper Mississippi
Valleys...
Southwesterly mid-level flow will remain in place today from the
central Plains into the mid to upper Mississippi Valley. At the
surface, a low is forecast to develop over the central Plains. To
the east of the low, low-level moisture is forecast to be maximized,
with surface dewpoints ranging from the mid 60s to the lower 70s F
across most of the mid Missouri Valley. As surface temperatures warm
during the day, scattered convective initiation is expected from
western and central Nebraska east-northeastward into Iowa, southern
Wisconsin and northern Illinois. Along this corridor, a low-level
jet will strengthen during the late afternoon and early evening.
This, combined with 30 to 35 knots of deep-layer shear, moderate
instability and steep low-level lapse rates will be favorable for a
severe threat. Damaging wind gusts and hail will be possible with
organized multicell line segments.

...Central and Northern High Plains...
A mid-level shortwave trough is forecast to move through the
southern and central Rockies today. Ahead of the trough, a moist and
unstable airmass will be in place by afternoon from eastern Colorado northwestward into eastern Montana. As surface temperatures warm
today, scattered convective initiation will take place in the higher
terrain, with storms moving east-northeastward into the lower
elevations during the afternoon. Moderate deep-layer shear and steep
low to mid-level lapse rates will support a marginal severe threat,
mainly in areas that heat up the most. A few damaging wind gusts and
hail will be the primary threats.

..Broyles/Moore.. 06/25/2025

$$

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ACUS01 KWNS 251241
SWODY1
SPC AC 251239

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0739 AM CDT Wed Jun 25 2025

Valid 251300Z - 261200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CAROLINAS...SOUTHEAST...AND MID MISSOURI VALLEY...

...SUMMARY...
Severe wind gusts are possible from parts of the Carolinas into the
Southeast, with widely scattered strong to severe storms possible
from the northern High Plains eastward to the Mid Atlantic.

...Synopsis...
A large upper ridge remains in place over much of the eastern CONUS
this morning, although an upper low centered northeast of the
Bahamas is beginning to impinge on its southeastern periphery.
Early-morning satellite imagery also shows a well-defined shortwave
trough moving through southern CA and southern Great Basin.

Recent surface analysis reveals a large reservoir of low-level
moisture beneath this upper ridge, with low 70s dewpoints over much
of the OH and TN Valleys, Mid-Atlantic, and Southeast. This
low-level moisture extends across much of the Plains as well, with
mid 60s dewpoints reaching into south-central/southeast SD. A
diffuse, somewhat wavy stationary boundary exists between this moist
airmass and the drier, more continental airmass edging into the
northern Plains, Upper Midwest, and Great Lakes.

This large area of ample low-level moisture will support potential thunderstorms much of the CONUS east of the Rockies. Highest
coverage of strong to severe storms is anticipated across the Mid MO
Valley and the Southeast/Mid-Atlantic, with more widely scattered
strong to severe storms across the northern and central High Plains
and along the frontal zone across the northern OH Valley.

...Mid-Atlantic/Southeast...
In addition to the moist airmass described in the synopsis, a pocket
of seasonally cold mid-level temperatures (i.e. around -10 deg C at
500 mb) associated with the Bahamas upper low extends into the
region. 12Z MHX and CHS soundings sampled -10 and -12 deg C at 500
mb, and 700-500 mb lapse rates of 7.9 and 8.4 deg C per km,
respectively. These thermodynamic conditions will result in very
strong buoyancy as the airmass diurnally heats this afternoon.
MLCAPE over 3000 J/kg is anticipated from AL eastward into the
Carolinas. Thunderstorm development is expected once convective
inhibition erodes around 18Z, with the very strong buoyancy
supporting intense updrafts. Vertical shear will be weak, with
erratic storm motions and a multicellular, pulse mode likely. Even
so, steep low-level lapse rates should support strong downdrafts and
numerous instances of damaging gusts are expected. These storms will
likely wane with the loss of daytime heating.

...Mid MO Valley into the Upper MS Valley...
Low-level moisture advection across the region today will bring low
70s dewpoints in southern MN by the late afternoon, while also
sharpening a warm frontal zone. By 18Z this warm front is forecast
to extend from a low over the central NE/SD border vicinity to near
the MN/IA border. Convergence along this boundary, as well as ascent
attendant to a convectively generated vorticity maximum rounding the
upper ridge, is expected to promote thunderstorm development within
the moderate buoyant airmass in place. Moderate southwesterly flow
aloft is anticipated over the region as well, with the resulting
combination of buoyancy and shear supporting strong to severe
storms. A few supercells are possible, but one or more bowing line
segments capable of damaging gusts are the primary severe threat.

...Northern/Central High Plains...
The shortwave trough that currently extends from central MT trough
eastern ID is forecast to continue eastward today. Ahead of the
trough, a moist and unstable airmass will be in place by afternoon
from eastern Colorado northwestward into eastern Montana. As surface temperatures warm today, scattered convective initiation will take
place in the higher terrain, with storms moving east-northeastward
into the lower elevations during the afternoon. Vertical shear will
be modest, with the strongest shear across the northern High Plains,
but high cloud bases and steep low-level lapse rates could still
support damaging wind gusts along surging cold pools. Isolated hail
is possible across the higher terrain as well.

..Mosier/Wendt.. 06/25/2025

$$

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ACUS01 KWNS 251608
SWODY1
SPC AC 251607

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1107 AM CDT Wed Jun 25 2025

Valid 251630Z - 261200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHWEST NORTH CAROLINA...CENTRAL AND NORTHERN SOUTH CAROLINA...AND
EASTERN GEORGIA....

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST
COLORADO INTO PARTS OF IOWA AND MINNESOTA....

...SUMMARY...
Severe wind gusts are possible from parts of the Carolinas into the
Southeast, with widely scattered strong to severe storms possible
from the northern High Plains eastward to the Mid Atlantic.

...Southeast US...
An unusually favorable thermodynamic pattern has evolved across the
southeast US today, with very steep mid-level lapse rates, cool
temperatures aloft, and strong daytime heating. Surface dewpoints
in the 70s will yield afternoon MLCAPE values over 3500 J/kg.

Large scale forcing is weak, suggesting convective initiation will
be poorly focused. However, most 12z CAM solutions show several
clusters of storms through the afternoon spreading southward from NC
into SC and eastern GA. Vertical shear is rather weak, suggesting
storms will be rather disorganized. However, there is a conditional
risk for an active day across the ENH risk, with considerable
coverage of damaging wind reports possible. As storms spread
southwestward this evening across GA, the risk of locally damaging
wind gusts will continue.

...NE/IA/MN...
Visible satellite imagery shows a developing differential heating
zone extending from south-central NE into central IA. Full sun to
the south of this zone will lead to strong instability and scattered
afternoon thunderstorm development. A band of 30-40 knot
southwesterly flow aloft atop this zone, coupled with strengthening
southerly low-level winds, will encourage organized/bowing clusters
of storms capable of damaging winds and some hail. A tornado or two
cannot be ruled out.

...CO/KS...
Thunderstorms will once again develop off the higher terrain of
CO/WY this afternoon and spread into the Plains. Model guidance
suggests steep low-level lapse rates and sufficient CAPE for severe
wind potential as these storms track toward northwest KS/southwest
NE by early evening.

...OH/WV...
Hot and humid conditions are present today across much of southern
OH into northern WV. Visible satellite imagery shows a developing
CU field, which may result in scattered slow-moving afternoon
thunderstorms. Winds aloft are rather weak, but the strongest cells
in this corridor may be capable of locally damaging wind gusts.

..Hart/Kerr.. 06/25/2025

$$

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ACUS01 KWNS 252001
SWODY1
SPC AC 251959

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Wed Jun 25 2025

Valid 252000Z - 261200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHWEST NORTH CAROLINA...CENTRAL AND NORTHERN SOUTH CAROLINA...AND
EASTERN GEORGIA...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST
COLORADO INTO PARTS OF IOWA...MINNESOTA...AND WISCONSIN...

...SUMMARY...
Severe wind gusts are expected from parts of the Carolinas into the
Southeast, with widely scattered strong to severe storms possible
from the northern/central High Plains eastward to the Mid Atlantic.

...20Z Update...
The primary change with this update was the addition of 5-percent
tornado probabilities along the warm front in southeast MN,
northeast IA, and far west-central WI. Here, a moist boundary layer
(lower 70s dewpoints) is gradually destabilizing amid diurnal
heating within cloud breaks. This continued destabilization and clockwise-curved low-level hodographs (sampled by ARX/MPX VWPs)
should support a locally favorable corridor for a couple supercell
tornadoes -- especially with additional strengthening of the
low-level jet. For details on the severe risks in the Southeast and
central Plains, see Severe Thunderstorm Watches 459 and 460.

..Weinman.. 06/25/2025

.PREV DISCUSSION... /ISSUED 1125 AM CDT Wed Jun 25 2025/

...Southeast US...
An unusually favorable thermodynamic pattern has evolved across the
southeast US today, with very steep mid-level lapse rates, cool
temperatures aloft, and strong daytime heating. Surface dewpoints
in the 70s will yield afternoon MLCAPE values over 3500 J/kg.

Large scale forcing is weak, suggesting convective initiation will
be poorly focused. However, most 12z CAM solutions show several
clusters of storms through the afternoon spreading southward from NC
into SC and eastern GA. Vertical shear is rather weak, suggesting
storms will be rather disorganized. However, there is a conditional
risk for an active day across the ENH risk, with considerable
coverage of damaging wind reports possible. As storms spread
southwestward this evening across GA, the risk of locally damaging
wind gusts will continue.

...NE/IA/MN...
Visible satellite imagery shows a developing differential heating
zone extending from south-central NE into central IA. Full sun to
the south of this zone will lead to strong instability and scattered
afternoon thunderstorm development. A band of 30-40 knot
southwesterly flow aloft atop this zone, coupled with strengthening
southerly low-level winds, will encourage organized/bowing clusters
of storms capable of damaging winds and some hail. A tornado or two
cannot be ruled out.

...CO/KS...
Thunderstorms will once again develop off the higher terrain of
CO/WY this afternoon and spread into the Plains. Model guidance
suggests steep low-level lapse rates and sufficient CAPE for severe
wind potential as these storms track toward northwest KS/southwest
NE by early evening.

...OH/WV...
Hot and humid conditions are present today across much of southern
OH into northern WV. Visible satellite imagery shows a developing
CU field, which may result in scattered slow-moving afternoon
thunderstorms. Winds aloft are rather weak, but the strongest cells
in this corridor may be capable of locally damaging wind gusts.

$$

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ACUS01 KWNS 260106
SWODY1
SPC AC 260104

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0804 PM CDT Wed Jun 25 2025

Valid 260100Z - 261200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THROUGH EARLY
TONIGHT FOR PARTS OF SOUTH CAROLINA AND EASTERN GEORGIA...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THROUGH LATE
EVENING FOR A SMALL AREA AROUND SOUTHWEST WISCONSIN...AND INTO
TONIGHT FROM SOUTH CAROLINA INTO SOUTHERN ALABAMA...

...SUMMARY...
Damaging outflow gusts and isolated large hail will remain possible
for the next several hours from South Carolina to southern Alabama.
A couple of tornadoes will be possible in the short term in the
vicinity of southwest Wisconsin.

...Southeast tonight...
Clusters of storms are ongoing across SC, where outflow mergers have
led to consolidation of a cold pool. The storms will likely persist
for several more hours while spreading southwestward over the
coastal plains of SC/GA, sustained by steeper-than-usual midlevel
lapse rates and strong buoyancy. Isolated large hail of 1-1.5
inches in diameter will remain a possibility with the stronger
embedded storms (especially with mergers), but damaging outflow
gusts will be the main threat with collapsing cores in the steep
lapse rate environment with strong downdraft potential (as suggested
by DCAPE of 1000-1500 J/kg).

Farther southwest, a few strong-severe storms will be possible
through about 02-03z along the conglomerate outflow from southwest
GA into southern AL.

...Southwest WI/southeast MN/northeast IA this evening...
Several tornadoes have been reported with supercells in a broken
band from northeast IA across far southeast MN into southwest WI.
These storms have trended toward a more linear mode over time and
the tornado threat appears to have already peaked. Prior to the
storms weakening early tonight, the potential for a couple of
tornadoes will persist for another 1-2 hours with the stronger
embedded supercells interacting with the warm front, where low-level
hodograph curvature/shear are maximized.

...Eastern NE/western IA this evening...
Convection has been largely undercut by convective outflow from
eastern NE into western IA. Moderate buoyancy remains immediately
to the south of the aggregate outflow/effective frontal boundary,
and profiles will remain sufficiently moist to maintain elevated
convection into the overnight hours. However, the potential for
severe storms appears to be diminishing with time, with only
isolated strong outflow gusts and/or marginally severe hail expected
beyond 01z.

...Northern High Plains through early tonight...
Widely scattered storms, some with supercell structure, will be
possible through about 03z. Thereafter, convection is expected to
weaken consistently with diurnal stabilization. In the interim,
isolated large hail of 1-1.5 inches in diameter will be possible.

..Thompson.. 06/26/2025

$$

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ACUS01 KWNS 260526
SWODY1
SPC AC 260525

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1225 AM CDT Thu Jun 26 2025

Valid 261200Z - 271200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
ACROSS NORTHERN IOWA INTO SOUTHWEST WISCONSIN...

...SUMMARY...
A few tornadoes and isolated wind damage will be possible this
afternoon from northern Iowa into southwest Wisconsin. Isolated
wind damage will be possible across a broad area of the eastern
Plains, Ohio Valley, Mid-Atlantic, the Southeast and Montana.

...Northern IA/southwest WI area this afternoon...
A weak midlevel trough over NE, enhanced by overnight convection,
will progress east-northeastward over IA during the afternoon, along
with an associated/weak wave along a surface baroclinic zone.
Modest enhancement to vertical shear along the baroclinic zone, and
MLCAPE near or above 2500 J/kg will support the potential for a band
of storms along and ahead of the front this afternoon. The
initial/more discrete storms could be supercells with the potential
to produce a few tornadoes, in addition to isolated wind damage and
marginally severe hail. Convection will likely grow upscale into a
line by late afternoon, and the severe threat will begin to diminish
by late evening.

...Southeast today...
Around the southeast periphery of a weakening midlevel high over KY,
a midlevel low will drift slowly west-northwestward over FL and
weaken gradually through tonight. Widespread convection is still
ongoing from late Wednesday evening across AL/GA, with relatively
widespread convective overturning and associated outflow. Remnant
outflows and differential heating zones will play a role in
additional thunderstorm development later this afternoon, though
regional reductions in surface temperatures/moisture from yesterday
will make the environment less favorable for widespread damaging
downbursts compared to Wednesday. Given the mesoscale complexity of
the pattern and reductions in lapse rates/buoyancy, will hold off on
adding any SLGT risk/15% wind areas in this outlook. However, some
part of GA/AL/MS may need to be reconsidered in later updates.

...OH Valley into the Mid-Atlantic this afternoon...
Scattered thunderstorms are expected again this afternoon in
association with daytime heating, residual boundaries from prior
convection, and terrain circulations. Though vertical shear will be
weak, steepening low-level lapse rates and precipitation loading
could support isolated wind damage with downbursts from mid
afternoon into the evening.

...Western OK to northeast KS this afternoon/evening...
Scattered thunderstorm development is expected this afternoon along
and ahead of weak front across KS, and farther to the south into the
strongly heated airmass and east edge of the midlevel moisture plume
now across west TX. Vertical shear will be weak through this
corridor, but thermodynamic profiles will favor strong downdrafts
and the potential for isolated strong-severe outflow gusts for a few
hours this afternoon/evening.

...MT this afternoon/evening...
A subtle midlevel trough and associated/diffuse front will move
across the northern Rockies this afternoon into tonight. Deep
mixing and inverted-V profiles will favor some potential for
strong-severe outflow gusts with scattered high-based thunderstorms
along and ahead of the diffuse front this afternoon into this
evening.

..Thompson/Moore.. 06/26/2025

$$

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ACUS01 KWNS 261235
SWODY1
SPC AC 261233

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0733 AM CDT Thu Jun 26 2025

Valid 261300Z - 271200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
ACROSS FAR SOUTHEAST MN...NORTHERN IA AND SOUTHERN WI...

...SUMMARY...
A few tornadoes and isolated wind damage will be possible this
afternoon from northern Iowa and southwest Minnesota into southwest
Wisconsin. Isolated wind damage will be possible across a broad area
of the eastern Plains, Ohio Valley, Mid-Atlantic, the Southeast and
Montana.

...Southern MN/IA/Southern WI...
Early morning radar and satellite imagery show a well-defined MCV
moving northeastward into eastern NE. Surface analysis reveals a low
over eastern NE, which is associated with this vorticity maximum as
well. A stationary boundary extends northeastward from this low
through northwestern IA to another low in the MN/IA/WI border
intersection vicinity. This boundary, which separates a moist
airmass characterized by 70s dewpoints from a more continental
airmass with low 60s dewpoints, could act as a favored corridor for northeastward progress of the surface low throughout the day. At the
same time, strengthening southerly low-level flow will increase the
low-level moisture advection south of this boundary, resulting in
some tightening of this boundary throughout the day. Some guidance
suggests this boundary could move slightly northward as a warm front
as well. This low-level moisture advection will also help offset
surface dewpoint reductions due to mixing, with dewpoints likely
remaining in the 70s along and south of the boundary. Strong heating
of this moist airmass will bring temperatures in the upper 70s/low
80s, fostering airmass destabilization and strong buoyancy by the
early afternoon.

Thunderstorm development is expected as the approaching vorticity
maximum and associated surface low interact with this unstable
airmass, with initiation occurring both near the surface low as well
as farther east amid the convergence along the warm front. The
development near the low should becoming linear quickly while the
activity along the front should remain more cellular longer. The
initial/more discrete storms could be supercells with the potential
to produce a few tornadoes within the moderately sheared and
vorticity rich environment along the front. Damaging gusts will be
possible with the linear segments as well, particularly in close
vicinity to the surface low where mesoscale circulations could
augment updrafts and downdrafts.

...Central/Eastern KS into Western/Central OK...
Recent surface analysis reveals weak surface troughing to the south
of a low over eastern NE. This troughing will likely shift eastward
as its parent low progresses northeastward, with convergence along
this boundary contributing to thunderstorms across central and
eastern KS. The character of the boundary will become more diffuse
with southern extent, but modest low-level confluence should still
be enough to support afternoon thunderstorm development. Vertical
shear will be weak through this entire corridor, but thermodynamic
profiles will favor strong downdrafts and the potential for isolated strong-severe outflow gusts for a few hours this afternoon/evening.

...Southeast...
Overnight convection has resulted in extensive cloudiness across
much of the region this morning. Even so, ample low-level moisture
remains in place and the airmass is expected to destabilize by the
early afternoon amid strong heating. Initial development appears
most likely near the westward progressing outflow moving across MS,
with additional development later near a convectively generated
vorticity maximum moving across central GA. Widespread storms are
also expected across FL as an upper low drifts slowly
west-northwestward. Shear will be weak areawide and a largely
disorganized storm mode is anticipated. Surging outflow is possible
with the strongest storms, fostering the potential for damaging
gusts and also contributing to additional storm development. Several forward-propagating clusters are possible although their location,
strength, and longevity are uncertain, precluding any increased
severe probabilities with this outlook.

...MT this afternoon/evening...
A subtle midlevel trough and associated/diffuse front will move
across the northern Rockies this afternoon into tonight. Deep
mixing and inverted-V profiles will favor some potential for
strong-severe outflow gusts with scattered high-based thunderstorms
along and ahead of the diffuse front this afternoon into this
evening.

...OH Valley into the Mid-Atlantic this afternoon...
Scattered thunderstorms are expected again this afternoon as the
airmass destabilizes amid strong daytime heating and ample low-level
moisture. Residual boundaries from prior convection, and terrain
circulations will act as favored areas for initiation. Vertical
shear will be weak, but steep low-level lapse rates and
precipitation loading could support isolated wind damage with
downbursts from mid afternoon into the evening.

..Mosier/Wendt.. 06/26/2025

$$

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ACUS01 KWNS 261611
SWODY1
SPC AC 261609

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1109 AM CDT Thu Jun 26 2025

Valid 261630Z - 271200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
FROM NORTHWEST MO INTO SOUTHERN MN/WI...AND FROM THE MID-ATLANTIC TO
THE SOUTHERN APPALACHIANS...

...SUMMARY...
Isolated wind damage and a few tornadoes will be possible this
afternoon from northwest Missouri into Iowa, southeast Minnesota,
and southern Wisconsin. Scattered wind damage will be possible from
the Mid-Atlantic into the southern Appalachians.

...Upper Midwest...
A shortwave trough is evident this morning over NE/SD moving
eastward. Lift ahead of this feature will encourage scattered
thunderstorm development by early afternoon near the surface low and
along a weak cold front over western IA. These storms will track
southeastward into a warm and very moist air mass, where MLCAPE
values will be 2000-3000 J/kg. Steep low-level lapse rates will
promote a risk of damaging winds as the storms spread southeastward
through early evening.

From the surface low eastward into southern WI, a corridor of backed
low-level winds and enhanced shear along the warm front will be
favorable for a few discrete supercells. Similar to yesterday
(although perhaps not quite as favorable), there is a risk of a few
tornadoes through the afternoon and early evening.

...Mid-Atlantic to Southern Appalachians...
Full sunshine is occurring again today from southeast PA to the
western Carolinas and north GA. This corridor will be hot/humid
again today, leading to scattered thunderstorms. Winds aloft are
weak, suggesting disorganized/pulse convective modes. However,
steep low-level lapse rates and moderate CAPE values will once again
result in a risk of locally damaging wind gusts through the
afternoon and early evening. Despite the expected weak winds aloft,
will introduce a SLGT risk for this corridor given the consensus of
model guidance supporting the threat.

..Hart/Thornton.. 06/26/2025

$$

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ACUS01 KWNS 262002
SWODY1
SPC AC 262000

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Thu Jun 26 2025

Valid 262000Z - 271200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
FROM NORTHWEST MISSOURI INTO SOUTHERN MINNESOTA/WISCONSIN...AND FROM
THE MID-ATLANTIC TO THE SOUTHERN APPALACHIANS...

...SUMMARY...
Isolated wind damage and a few tornadoes will be possible this
afternoon from northwest Missouri into Iowa, southeast Minnesota,
and southern Wisconsin. Scattered wind damage will be possible from
the Mid-Atlantic into the southern Appalachians.

...20Z Update...
The forecast remains on track, and only minor adjustments were made
with this update. In particular, the Slight risk was expanded
eastward in IA and northern MO -- where warm/moist boundary-layer
conditions should support the maintenance of an eastward-moving line
of storms (with an associated severe-wind risk) into this evening.
Reference Severe Thunderstorm Watch 465 for more information on the
severe risk here. Farther north, the potential for tornadoes will
continue with both pre-frontal cells within the baroclinic zone in
southern WI and with the primary confluence band advancing eastward
out of southeastern MN. An upgrade to 10-percent tornado
probabilities was considered, but overall confidence in this
scenario was too low for the upgrade at this time. For more details,
see Tornado Watch 463 and MCD 1458. Finally, the damaging wind gusts
will remain possible with evolving storms in the Mid-Atlantic
(within Severe Thunderstorm Watch 464).

..Weinman.. 06/26/2025

.PREV DISCUSSION... /ISSUED 1109 AM CDT Thu Jun 26 2025/

...Upper Midwest...
A shortwave trough is evident this morning over NE/SD moving
eastward. Lift ahead of this feature will encourage scattered
thunderstorm development by early afternoon near the surface low and
along a weak cold front over western IA. These storms will track
southeastward into a warm and very moist air mass, where MLCAPE
values will be 2000-3000 J/kg. Steep low-level lapse rates will
promote a risk of damaging winds as the storms spread southeastward
through early evening.

From the surface low eastward into southern WI, a corridor of backed
low-level winds and enhanced shear along the warm front will be
favorable for a few discrete supercells. Similar to yesterday
(although perhaps not quite as favorable), there is a risk of a few
tornadoes through the afternoon and early evening.

...Mid-Atlantic to Southern Appalachians...
Full sunshine is occurring again today from southeast PA to the
western Carolinas and north GA. This corridor will be hot/humid
again today, leading to scattered thunderstorms. Winds aloft are
weak, suggesting disorganized/pulse convective modes. However,
steep low-level lapse rates and moderate CAPE values will once again
result in a risk of locally damaging wind gusts through the
afternoon and early evening. Despite the expected weak winds aloft,
will introduce a SLGT risk for this corridor given the consensus of
model guidance supporting the threat.

$$

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ACUS01 KWNS 270057
SWODY1
SPC AC 270055

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0755 PM CDT Thu Jun 26 2025

Valid 270100Z - 271200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR THE NEXT
COUPLE OF HOURS ACROSS EASTERN IOWA INTO SOUTHWESTERN WISCONSIN...

...SUMMARY...
Isolated wind damage and marginally severe hail will be the main
threats through late evening/early tonight from eastern Kansas into
southern Wisconsin, parts of the Mid-Atlantic and Appalachians, the
Texas Panhandle, and eastern Montana.

...Eastern KS to southern WI through late evening...
Convection has evolved into a line of storms from northwest MO into
eastern IA and southwest WI along a conglomerate outflow, in advance
of a weak midlevel trough approaching the upper MS Valley.
Weakening buoyancy with the loss of daytime heating and weakening
vertical shear over time in the warm sector suggests that the storms
are likely past peak, though isolated wind damage will remain
possible for the next 2 hours or so before the storms weaken
sufficiently and the low levels stabilize.

...Mid-Atlantic and Appalachians through 03z...
Scattered thunderstorms are ongoing in multiple small clusters from
central NC into VA/WV/MD and southern PA. A few strong storms with
isolated wind damage will be possible through about 02-03z,
especially with storm mergers, before gradual stabilization of the
boundary layer brings an end to the largely diurnal severe threat.

...TX Panhandle through late evening...
A few storm clusters are ongoing across the central TX Panhandle to
the TX/NM state line. Lingering steep low-level lapse rates, modest
vertical shear and storm/outflow mergers could maintain a marginal
severe threat for another few hours before buoyancy weakens and the
storms diminish.

...Eastern MT this evening...
Deep-layer vertical shear is not particularly strong and low-level
moisture is limited, but steep lapse rates through the low-midlevels
are sustaining a couple of stronger storm clusters across northeast
MT where low-level moisture is a bit richer. There will remain
sufficient midlevel moisture/ascent downstream of an ejecting
midlevel trough to maintain the potential for thunderstorms for the
next several hours. Isolated strong outflow gusts may occur with
the high-based convection into central MT, while isolated strong
gusts and marginally severe hail will remain possible this evening
across eastern MT.

..Thompson.. 06/27/2025

$$

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ACUS01 KWNS 270505
SWODY1
SPC AC 270503

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1203 AM CDT Fri Jun 27 2025

Valid 271200Z - 281200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THE AFTERNOON
INTO EARLY TONIGHT ACROSS THE NORTHERN PLAINS...AND THIS
AFTERNOON/EVENING ACROSS SOUTHEAST LOWER MICHIGAN...

...SUMMARY...
At least widely scattered thunderstorms are expected late this afternoon/evening across the Dakotas and Nebraska, where very large
hail and severe outflow winds will be possible. There will also be
a window of opportunity for tornadoes this evening across the
central Dakotas. Occasional wind damage will be possible this afternoon/evening across southeast Lower Michigan.

...Northern Plains late this afternoon into early tonight...
A low-amplitude midlevel trough with embedded speed maxima will move
eastward from the northern Rockies to the northern High Plains
through tonight. At the surface, lee cyclogenesis is expected this
afternoon in the vicinity of northeast WY, while low-level moisture
spreads northward across the Dakotas through this evening. The
moistening will occur beneath an elevated mixed layer with midlevel
lapse rates of 8.5-9.5 C/km, and daytime heating will result in
MLCAPE exceeding 4000 J/kg. The elevated mixed layer will also act
as a cap and surface temperatures will need to reach the mid 90s in
SD and the mid-upper 80s in ND to largely eliminate convective
inhibition. As such, storm timing/coverage is a bit uncertain with
modest forcing for ascent.

Where storms form, the steep lapse rates/extreme buoyancy and
effective bulk shear in excess of 40 kt will conditionally favor
supercells with very large hail (potentially greater than 3 inches
in diameter). There could also be a window of opportunity for
tornadoes as low-level shear increases in the evening, where storms
remain discrete prior to convective inhibition increasing tonight.
Otherwise, any storm clusters will have the potential to produce
severe outflow winds of 60-80 mph, especially in the deeper mixed
environment farther south in SD.

...Southeast Lower MI this afternoon/evening...
A midlevel shortwave trough and associated weak wave cyclone now
over the upper MS Valley will continue eastward over the upper Great
Lakes through this evening, while a trailing cold front crosses
Lower MI. Daytime heating and boundary-layer dewpoints in the low
70s in the warm sector will contribute to MLCAPE above 2000 J/kg
during the afternoon across Lower MI as convective inhibition
weakens. Low-level ascent along the front will support a broken
band of storms by mid afternoon, and the storms will spread eastward
before weakening by late evening. Though midlevel lapse rates and
deep-layer vertical shear will not be strong, ~35 kt midlevel flow
and steep low-level lapse rates suggest the potential for occasional
wind damage with multicell clusters and/or short line segments.

...Appalachians into the Southeast this afternoon/evening...
Another afternoon/evening of widely scattered thunderstorms and
isolated downburst potential is expected across a broad area from
the Appalachians into the Southeast/FL. Local sea breeze
circulations, terrain circulations and residual outflow/differential
heating zones will help focus thunderstorm development.
Thermodynamic profiles will be sufficient for isolated wind damage
with downbursts.

..Thompson/Lyons.. 06/27/2025

$$

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ACUS01 KWNS 271211
SWODY1
SPC AC 271210

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0710 AM CDT Fri Jun 27 2025

Valid 271300Z - 281200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THIS
AFTERNOON INTO EARLY TONIGHT ACROSS THE NORTHERN PLAINS...AND THIS AFTERNOON/EVENING ACROSS SOUTHEAST LOWER MICHIGAN...

...SUMMARY...
At least widely scattered thunderstorms are expected late this afternoon/evening across the Dakotas and Nebraska, where very large
hail and severe outflow winds will be possible. There will also be
a window of opportunity for tornadoes this evening across the
central Dakotas. Occasional wind damage will be possible this afternoon/evening across southeast Lower Michigan.

...Northern Plains late this afternoon into early tonight...
Water-vapor imagery this morning shows a mid-level disturbance
moving east across the northern Rockies. This upper feature and an
associated belt of stronger flow will move eastward into the
northern Great Plains tonight. In the low levels, southerly flow
will contribute to moisture return northward into the Dakotas as a
low develops near the SD/WY border. Steep midlevel lapse rates of
8.5-9.5 C/km, and daytime heating will result in MLCAPE exceeding
4000 J/kg within the moisture plume where boundary-layer moisture is
highest.

A cap will likely inhibit storm development through the mid
afternoon before heating and the resultant erosion of convective
inhibition favors initially isolated storm development. Forecast
soundings show very steep low to mid-tropospheric lapse rates, large
to extreme buoyancy, and effective shear supporting organized
storms. The initial activity will likely be supercellular with an
attendant risk for large to giant hail with the stronger supercells.
A period of opportunity for an isolated tornado risk may realize
during the early evening, coincident with a slight intensification
of low-level shear, while maintaining a favorable storm mode. A
couple of clusters are forecast to evolve during the evening with
significant gusts (75-90 mph) possible in the more intense clusters.
A lingering risk for mainly wind and perhaps hail will gradually
wane towards the late evening and early overnight as this activity
gradually shifts east.

...Southeast Lower MI this afternoon/evening...
Not much change to the previous forecast scenario. A midlevel
shortwave trough and associated weak wave cyclone now over the Upper
MS Valley will continue eastward over the Upper Great Lakes through
this evening, while a trailing cold front crosses Lower MI. Daytime
heating and lower 70s deg F dewpoints will yield moderate buoyancy
by the early afternoon. Low-level ascent along the front will
support a broken band of storms by mid afternoon, and the storms
will spread eastward before weakening by late evening. Though
midlevel lapse rates and deep-layer vertical shear will not be
strong, ~35 kt midlevel flow and steep low-level lapse rates suggest
the potential for scattered 55-70 mph gusts capable of wind damage
with the stronger storms and linear clusters.

...Appalachians into the Southeast this afternoon/evening...
Another afternoon/evening of widely scattered thunderstorms and
isolated downburst potential is expected across a broad area from
the Appalachians into the Southeast/FL. Local sea breeze
circulations, terrain circulations and residual outflow/differential
heating zones will help focus thunderstorm development. The more
intense storms and small-scale clusters will likely yield a risk for
45-65 mph gusts and pockets of wind damage.

..Smith/Broyles.. 06/27/2025

$$

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ACUS01 KWNS 271616
SWODY1
SPC AC 271614

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1114 AM CDT Fri Jun 27 2025

Valid 271630Z - 281200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
FROM NORTHERN IN INTO SOUTHEAST LOWER MI...AND THIS
AFTERNOON/TONIGHT ACROSS THE NORTHERN PLAINS...

...SUMMARY...
Scattered thunderstorms are expected late this afternoon/evening
across the Dakotas and Nebraska, where very large hail, severe
outflow winds, and a few tornadoes will be possible. Occasional
wind damage will be possible this afternoon from northern Indiana
into southeast Lower Michigan.

...Dakotas/NE/MN...
Water vapor imagery shows a fast-moving shortwave trough moving
across MT. As this feature overspreads the northern Plains this afternoon/evening, scattered thunderstorm development is expected
from western ND into central/western SD. Storms will track
southeastward in a moist and very unstable air mass, where steep
mid-level lapse rates and sufficient vertical shear will support the development of supercells. Very large hail and a few tornadoes are
possible with this early activity. Congealing outflows after dark
may result in one or more bowing segments capable of severe wind
gusts. Have expanded the SLGT a little farther east into MN to
account for various morning CAM solutions.

...Lower MI...
Visible satellite imagery shows clear skies from northern IN into
southeast Lower MI, with dewpoints in the 70s and afternoon CAPE
values expected in the 2000-3000 J/kg range. A weak shortwave
trough will pass to the north of this area, providing weak lift and
aiding in thunderstorm development by mid afternoon. Steep
low-level lapse rates will promote a risk of damaging wind gusts in
the stronger cells.

...East TN/north GA...
Another active day of scattered thunderstorms is expected, with
hot/humid conditions aiding in the risk of locally damaging wind
gusts and some hail in the stronger cells.

..Hart/Grams.. 06/27/2025

$$

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ACUS01 KWNS 272001
SWODY1
SPC AC 272000

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Fri Jun 27 2025

Valid 272000Z - 281200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
CENTRAL NORTH DAKOTA...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHERN
INDIANA INTO SOUTHEAST LOWER MICHIGAN...

...SUMMARY...
Scattered thunderstorms are expected late this afternoon/evening
across the Dakotas and Nebraska, where very large hail, severe
outflow winds, and a few tornadoes will be possible. Occasional
wind damage will be possible this afternoon from northern Indiana
into southeast Lower Michigan.

...20Z Update...
The primary change with this update was the addition of an Enhanced
risk over parts of central ND -- driven by 30-percent hail
probabilities. Based on the latest high-resolution guidance and
observations, confidence has increased that several semi-discrete
supercells capable of producing very large hail will evolve along
the northern periphery of strong to extreme surface-based buoyancy
and very favorable deep-layer shear into tonight. Elsewhere, only
minor changes were made to the outlook. For information on the
severe risk in Lower MI and northern IN, reference Severe
Thunderstorm Watch 466.

..Weinman.. 06/27/2025

.PREV DISCUSSION... /ISSUED 1114 AM CDT Fri Jun 27 2025/

...Dakotas/NE/MN...
Water vapor imagery shows a fast-moving shortwave trough moving
across MT. As this feature overspreads the northern Plains this afternoon/evening, scattered thunderstorm development is expected
from western ND into central/western SD. Storms will track
southeastward in a moist and very unstable air mass, where steep
mid-level lapse rates and sufficient vertical shear will support the development of supercells. Very large hail and a few tornadoes are
possible with this early activity. Congealing outflows after dark
may result in one or more bowing segments capable of severe wind
gusts. Have expanded the SLGT a little farther east into MN to
account for various morning CAM solutions.

...Lower MI...
Visible satellite imagery shows clear skies from northern IN into
southeast Lower MI, with dewpoints in the 70s and afternoon CAPE
values expected in the 2000-3000 J/kg range. A weak shortwave
trough will pass to the north of this area, providing weak lift and
aiding in thunderstorm development by mid afternoon. Steep
low-level lapse rates will promote a risk of damaging wind gusts in
the stronger cells.

...East TN/north GA...
Another active day of scattered thunderstorms is expected, with
hot/humid conditions aiding in the risk of locally damaging wind
gusts and some hail in the stronger cells.

$$

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ACUS01 KWNS 280042
SWODY1
SPC AC 280041

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0741 PM CDT Fri Jun 27 2025

Valid 280100Z - 281200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTH DAKOTA...

...SUMMARY...
Scattered severe thunderstorms are expected across the northern
Plains this evening. Very large hail, severe gusts, and a few
tornadoes can be expected.

...01z Update...

Short-wave ridge is flattening a bit across the northern Plains
early this evening as several weak disturbances are ejecting across
the northern Rockies into the High Plains of eastern MT/western ND.
Over the last few hours, scattered supercells have developed along
the northern edge of strong buoyancy across ND. 00z sounding from
BIS exhibited MLCAPE around 2300 J/kg with very steep low-midlevel
lapse rates. This activity is maturing along/near a surface boundary
that is draped from east of Minot to near Dickinson ND, trailing
into the northern portions of the Black Hills of SD. Just upstream, satellite/radar imagery suggest a weak short-wave trough is
approaching eastern MT. A very weak MCV may be noted just west of
Jordan and this feature could encourage upscale growth downstream
later this evening as the LLJ increases, partly in response to the
short wave. 1km VAD flow is already around 20kt at BIS, and marked
increase should be noted over the next few hours. With time, ongoing
convection may gradually coalesce into an MCS which would propagate
downstream along the nose of the LLJ into the upper Red River
region. Until then, very large hail may occur with ongoing
supercells, along with some risk for a few tornadoes. Damaging winds
may become more common as the MCS evolves later this evening.

..Darrow.. 06/28/2025

$$

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ACUS01 KWNS 280542
SWODY1
SPC AC 280541

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1241 AM CDT Sat Jun 28 2025

Valid 281200Z - 291200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER
MIDWEST TO THE BLACK HILLS REGION...

...SUMMARY...
Scattered strong to severe thunderstorms, perhaps including one or
two organizing clusters, will pose a risk for severe hail, wind and
perhaps a couple of tornadoes across parts of the Upper Midwest into
the Plains of South Dakota and Nebraska.

...Upper Midwest to the Black Hills of South Dakota...

Seasonally typical early summer pattern will be noted today as
stronger westerlies are confined to the northern U.S., and much
weaker flow is observed across the southern two-thirds of the CONUS.
Latest water-vapor imagery suggests a few weak disturbances are
translating across the northern Rockies toward the northern Plains
and this will shunt the primary synoptic boundary across much of the
Dakotas into the upper MS Valley by early evening. This boundary
will prove instrumental in focusing deep convection during the afternoon/evening hours.

Early this morning, scattered clusters of strong/severe
thunderstorms are propagating southeast across the eastern Dakotas.
This activity will advance into the upper MS Valley early in the
period as LLJ focuses across eastern SD into northern MN. While some
severe threat will be noted with a possible MCS at daybreak,
convective outflow will largely influence subsequent regeneration.
Latest model guidance suggests an east-west boundary will drape
itself across western WI/southern MN by 18z, likely modified by the aforementioned early-day MCS. Boundary-layer heating is expected to
aid buoyancy across the Dakotas southeast of the cold front, and
scattered thunderstorms should readily develop along this wind shift
by late afternoon, aided in part by a weak short wave trough.
Additional convection is also possible along the outflow. Wind
profiles favor some supercell development, along with possible
clusters. Very large hail could accompany supercells. The east-west
boundary should enhance low-level shear such that a higher
probability for tornadoes will exist across southern portions of MN.

Stronger heating across the Plains of NE into eastern WY will aid isolated-scattered thunderstorms across this portion of the SLGT
Risk. Higher-based updrafts, but steep lapse rates suggest hail/wind
will be the primary concerns.

...Northern Middle Atlantic region and upper Ohio Valley...

Weak short-wave trough is advancing east across the upper Great
Lakes region early this morning. Southern influence of this feature
will encourage convective development by 18z across the upper OH
Valley into upstate NY. Modest west-southwesterly flow at mid levels
suggests some convective organization is possible; however, poor
lapse rates and modest instability should result in mainly a
damaging wind threat with the most organized convection. Some
consideration was given for higher probabilities across portions of
the northern Middle Atlantic into southern NY, but weak lapse rates
are concerning and deep-layer shear is not that strong. Even so,
gusty winds will likely be noted with this activity as it spreads
across PA/NY toward the western parts of southern New England.

..Darrow/Lyons.. 06/28/2025

$$

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ACUS01 KWNS 281201
SWODY1
SPC AC 281200

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0700 AM CDT Sat Jun 28 2025

Valid 281300Z - 291200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER
MIDWEST TO THE BLACK HILLS...AND PARTS OF NEW YORK AND
PENNSYLVANIA...

...SUMMARY...
Scattered severe thunderstorms are possible across portions of the
Upper Midwest into the north-central Great Plains. All severe
hazards are possible centered on southern Minnesota and eastern
South Dakota. Scattered damaging gusts are possible across parts of
New York into Pennsylvania.

...Upper Midwest to the Black Hills of South Dakota...
Broad weak troughing per morning water-vapor imagery over the
northern Rockies/High Plains will gradually shift eastward and
become centered over MB/SK and the Dakotas by the end of the period.
A somewhat ill-defined boundary this morning will become draped from
parts of the upper MS Valley west-southwestward into the Black Hills
later this afternoon/evening.

Residual clusters of showers/weak thunderstorms this morning will
likely dissipate by mid-late morning over the Upper Midwest. The
resultant convective outflow will probably prove instrumental in
renewed thunderstorm activity later this afternoon where
differential heating/convergence will become focused.
Isolated to scattered thunderstorms should readily develop along the front/composite outflow by late afternoon when buoyancy will be
maximized. Forecast soundings show 3000-4500 J/kg MLCAPE developing
from eastern SD into MN/western WI. It appears sufficient hodograph
curvature and effective shear magnitudes around 30 kt will support a
supercell mode, at least initially. All severe hazards will be
possible. Gradual upscale growth into a cluster may occur during
the evening --supported by a persistent southwesterly LLJ-- with the
risk gradually favoring more of a wind threat.

Stronger heating across the Plains of NE into eastern WY will aid isolated-scattered thunderstorms across this portion of the SLGT
Risk. Higher-based updrafts, but steep lapse rates suggest hail/wind
will be the primary concerns.

...Northeast into the Mid-Atlantic region and upper Ohio Valley...
Morning satellite imagery indicates a weak mid-level trough near
Georgian Bay/southern ON. This feature is forecast to move eastward
to the VT/NH/QC vicinity by early evening and glance NY/PA. In
agreement with earlier forecast thinking, the southern extent of the disturbance's influence will aid in storm development within the
northeast extent of richer moisture extending from the upper OH
Valley into the PA/southern NY area. Initial extensive low cloud
cover will gradually abate as diurnal heating aids in moderate
destabilization by midday from southern NY southwestward into the
upper OH Valley. Bands of smaller storm clusters preferentially
developing on the front/wind shift will predominately be
multicellular, and pose a wind-damage risk across parts of PA during
the afternoon/early evening. Slightly stronger low to mid-level
flow over NY may favor a mix of strong to severe multicells and
perhaps transient, weak supercell structure. Farther south,
slow-moving isolated to scattered pulse-like storms will yield an
isolated risk for 50-60 mph gusts capable of wind damage with the
more intense water-loaded downdrafts.

..Smith/Broyles.. 06/28/2025

$$

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ACUS01 KWNS 281627
SWODY1
SPC AC 281626

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1126 AM CDT Sat Jun 28 2025

Valid 281630Z - 291200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
FROM CENTRAL PENNSYLVANIA INTO SOUTHEAST NEW YORK. OTHER SEVERE
STORMS WILL OCCUR FROM THE BLACK HILLS REGION INTO PARTS OF
MINNESOTA AND WESTERN WISCONSIN....

...SUMMARY...
Scattered severe thunderstorms are possible across portions of the
Upper Midwest into the north-central Great Plains. All severe
hazards are possible centered on southern Minnesota and eastern
South Dakota. Scattered damaging gusts are possible across parts of
New York into Pennsylvania.

...Eastern SD/MN/WI...
Current radar loops show a persistent MCS slowly weakening across
southern MN. This feature has driven an associated outflow boundary
into northwest IA and eastern SD. Morning model solutions are in
general agreement that the low-level air mass will rapidly recover
in the wake of the MCS, leading to rapid and intense thunderstorm
development by late afternoon over western MN. It is unclear if the
models are handling the lingering effects of the morning convection,
but the eventual re-development of storms poses risks of tornadoes,
very large hail, and damaging winds. An upgrade to ENH risk over
parts of central/southern MN for this evening was considered, but
will defer to the 20z outlook, after further evaluation of the
ongoing convection and trends in destabilization.

...Western SD Vicinity...
Full sun will lead to strong heating and deep mixing across much of
eastern WY today. High-based convection will develop by late
afternoon in this region and spread eastward into a progressively
more moist and unstable air mass over western SD. Scattered intense
storms are expected to develop, posing a risk of large hail and
damaging wind gusts. These storms may persist through the evening
and grow upscale, with a risk of damaging winds into southern
SD/northern NE.

...NY/PA/Mid-Atlantic...
A surface cold front is sagging southward into NY and western PA
today. Thunderstorms have begun to intensify along/ahead of the
front, with locally damaging wind gusts expected through the
afternoon. Low clouds are limiting heating/destabilization over
eastern NY/PA and the Mid-Atlantic region. However, heating should
commence by mid/late afternoon, allowing storms approaching from the
west to maintain a damaging wind threat into the early evening.

..Hart/Squitieri.. 06/28/2025

$$

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ACUS01 KWNS 282001
SWODY1
SPC AC 282000

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Sat Jun 28 2025

Valid 282000Z - 291200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF PENNSYLVANIA AND NEW YORK AS WELL AS ACROSS PORTIONS OF THE NORTHERN
PLAINS....

...SUMMARY...
Scattered severe thunderstorms are possible across portions of the
Upper Midwest into the north-central Great Plains. All severe
hazards are possible centered on southern Minnesota and eastern
South Dakota. Scattered damaging gusts are possible across parts of
New York into Pennsylvania.

...20Z Update...

The main change with this update is to expand the hail threat
farther north and west into portions of east-central North Dakota
and west-central Minnesota. Here, strong instability and
developing/ongoing thunderstorms will be capable of producing large
hail. See MCD #1492 for additional meteorological discussion.

Elsewhere, only minor changes were made to the ongoing forecast.

..Marsh.. 06/28/2025

.PREV DISCUSSION... /ISSUED 1126 AM CDT Sat Jun 28 2025/

...Eastern SD/MN/WI...
Current radar loops show a persistent MCS slowly weakening across
southern MN. This feature has driven an associated outflow boundary
into northwest IA and eastern SD. Morning model solutions are in
general agreement that the low-level air mass will rapidly recover
in the wake of the MCS, leading to rapid and intense thunderstorm
development by late afternoon over western MN. It is unclear if the
models are handling the lingering effects of the morning convection,
but the eventual re-development of storms poses risks of tornadoes,
very large hail, and damaging winds. An upgrade to ENH risk over
parts of central/southern MN for this evening was considered, but
will defer to the 20z outlook, after further evaluation of the
ongoing convection and trends in destabilization.

...Western SD Vicinity...
Full sun will lead to strong heating and deep mixing across much of
eastern WY today. High-based convection will develop by late
afternoon in this region and spread eastward into a progressively
more moist and unstable air mass over western SD. Scattered intense
storms are expected to develop, posing a risk of large hail and
damaging wind gusts. These storms may persist through the evening
and grow upscale, with a risk of damaging winds into southern
SD/northern NE.

...NY/PA/Mid-Atlantic...
A surface cold front is sagging southward into NY and western PA
today. Thunderstorms have begun to intensify along/ahead of the
front, with locally damaging wind gusts expected through the
afternoon. Low clouds are limiting heating/destabilization over
eastern NY/PA and the Mid-Atlantic region. However, heating should
commence by mid/late afternoon, allowing storms approaching from the
west to maintain a damaging wind threat into the early evening.

$$

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ACUS01 KWNS 290050
SWODY1
SPC AC 290049

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0749 PM CDT Sat Jun 28 2025

Valid 290100Z - 291200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER
MIDWEST INTO THE NORTHERN HIGH PLAINS...

...SUMMARY...
Scattered severe thunderstorms will spread across the upper Midwest
and portions of the northern Plains this evening into the overnight
hours. All severe hazards are possible.

...01z Update...

Short-wave ridging has flattened across the northern Plains/upper
Midwest as broader cyclonic flow now extends across the northern
Rockies into the eastern Dakotas. This flow regime is notably
diffluent across the upper Midwest, and scattered deep convection is
maturing within this favorable environment from the upper Red River
Valley into southwestern MN. While LLJ is not particularly strong at
this time, latest model guidance suggests 1km flow could increase in
excess of 35kt across southern MN by mid-late evening. Scattered
supercells have evolved near the SD/MN border, and this activity
could grow upscale as it propagates downstream along a weak
boundary, aided by the aforementioned increase in LLJ and associated
low-level warm advection. 00z sounding from ABR exhibited MLCAPE
around 3000 J/kg with adequate deep-layer shear for sustaining
organized updrafts. This supports the potential for all hazards with
these storms into the late-evening hours.

Upstream across the High Plains, water-vapor imagery suggests a weak disturbance is ejecting across southern MT, and this feature will
shift into the western Dakotas by the end of the period. Isolated
thunderstorms developed over the higher terrain southwest of
Billings MT, and there is some concern for additional development
ahead of the short wave later tonight as it encounters a bit more moisture/instability over southeast MT into the Black Hills region.
Until then, a long-lived supercell is digging southeast across
Jackson County SD, just south of Phillip. This storm has a history
of producing very large hail and damaging winds. This activity may
remain somewhat isolated as it propagates toward south central SD
later this evening.

..Darrow.. 06/29/2025

$$

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ACUS01 KWNS 290551
SWODY1
SPC AC 290550

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1250 AM CDT Sun Jun 29 2025

Valid 291200Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER
MIDWEST TO THE CENTRAL HIGH PLAINS...

...SUMMARY...
Isolated to scattered strong to severe thunderstorms are possible
from the upper Great Lakes into the central High Plains. Wind is the
primary risk, though hail is expected across portions of the High
Plains.

...Upper Great Lakes to the Central High Plains...

Broadly cyclonic westerlies, currently noted over the northern
Plains, will gradually shift east and sag south across the upper MS
Valley late in the period. Mid-level flow south of I-70 will remain
seasonally weak, and the prospect for organized convection south of
this corridor is low.

Early this morning, a weak synoptic front stretched from
northwestern MN into northern NE before arcing into eastern WY. This
boundary is forecast to sag south and east through the period with a late-afternoon position expected from northern WI-central
IA-northwest KS-arcing into southeast WY. This boundary will likely
serve as the focus for robust convection during the
afternoon/evening hours. Diurnal heating will prove instrumental in
convective development and the strongest boundary-layer heating will
be noted across the High Plains into extreme southeast NE.
Convective temperatures will be easily breached along the boundary
over northern KS as temperatures soar through the upper 90s to near
100F. Forecast soundings exhibit cloud bases near 3km in this
environment and fairly high PWs favor damaging winds despite the
relative weak shear across this region.

Farther northeast, remnants of early-day convection will spread
across southern MN/northwest IA. This activity will propagate
southeast and likely influence redevelopment where differential
heating is greatest. Some short-range guidance suggests an MCS may
propagate south along the NE/IA border, with some upscale growth
possible by early evening. While not all models agree, this signal
is likely real, especially as a weak LLJ is forecast across eastern
KS into northwest MO into the evening.

Another corridor where strong/severe convection is expected is
across the High Plains from eastern WY into northeast CO. Northwest
flow is forecast to strengthen across the northern High Plains along
the back side of the trough. Isolated supercells are expected to
develop along the synoptic front that will be draped across this
region. Forecast soundings do not exhibit strong buoyancy, but
modest shear and moist profiles favor organized updrafts that should
spread southeast toward the NE Panhandle. Large hail and wind are
expected.

...Middle Atlantic...

Seasonally high PW values and light west-southwesterly mid-level
flow will once again favor a few slow-moving line segments and
clusters. Storms will be diurnally driven, and convection should
focus along a very weak zone of low-level confluence that should
extend across the Delmarva into central VA. Locally strong gusts are
the primary concern.

..Darrow/Lyons.. 06/29/2025

$$

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ACUS01 KWNS 291232
SWODY1
SPC AC 291230

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0730 AM CDT Sun Jun 29 2025

Valid 291300Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER
MIDWEST TO THE CENTRAL HIGH PLAINS...

...SUMMARY...
Isolated to scattered strong to severe thunderstorms are possible
from the upper Great Lakes into the central High Plains. Wind is the
primary risk, though hail is expected across portions of the High
Plains.

...Upper Great Lakes to the Central High Plains...
Belt of stronger westerlies will remain confined to the
U.S.-Canadian border states as a mid- to upper-level trough shifts
east from the MT/ND vicinity into the Upper Midwest late. A surface
front is analyzed this morning from the Upper Midwest, where it is
ill defined and modulated by convective outflow, southwestward into
northern KS and arcing west-northwest into the central High Plains.
Some eastward movement is forecast during the day across the Upper
Midwest whereas the frontal segment over the central Great Plains
will become stationary this afternoon. This boundary and associated
composite outflow will serve as the primary focus for renewed shower/thunderstorm activity this afternoon into tonight.

A decaying MCS over western IA/southeast NE this morning will
further weaken and an ongoing corridor of weak thunderstorms extends
southeast from the MCS through the lower MO Valley. Removed from
cloud debris, strong heating of a seasonably moist boundary layer
will result in strong destabilization from WI southwestward into KS,
where 2000-3500 J/kg MLCAPE is forecast by mid afternoon. The
aforementioned displacement of this region from stronger mid and
high-level flow will limit potential for greater storm organization.
However, isolated to scattered thunderstorms will likely evolve into
several small-scale bands and clusters from the western Great Lakes
into the lower MO Valley posing mainly a wind risk with the stronger
storms. Stronger heating farther west over central KS westward into
parts of the central High Plains will result in steep low to
mid-level tropospheric lapse rates. Evaporative cooling of stronger water-laden downdrafts will yield a threat for severe gusts across
the central Great Plains into the lower MO Valley. Hail may
accompany the stronger cores, but this risk will be limited by a
deep melting layer and a multicellular storm mode. A couple of
clusters may persist through the evening and into the overnight as
this activity shifts southward, perhaps into southeast KS and
northern OK late.

Another corridor where strong/severe convection is expected is
across the High Plains from eastern WY into northeast CO. Northwest
flow is forecast to strengthen across the northern High Plains along
the back side of the trough. Isolated supercells are expected to
develop along the synoptic front that will be draped across this
region. Forecast soundings do not exhibit strong buoyancy, but
modest shear and moist profiles favor organized updrafts that should
spread southeast toward the NE Panhandle. Large hail and wind are
expected.

...Mid Atlantic states...
A moist and moderately unstable airmass will favor isolated to
scattered thunderstorms developing during the afternoon across the
region. High PW and steepened surface to 850-mb lapse rates amidst
weak shear will result in relatively disorganized individual storms
and smaller clusters. Localized strong to severe gusts (50-60 mph)
may result and yield pockets of wind damage with the stronger cores.

..Smith/Broyles.. 06/29/2025

$$

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ACUS01 KWNS 291632
SWODY1
SPC AC 291630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Sun Jun 29 2025

Valid 291630Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE CENTRAL PLAINS...AND PORTIONS OF IOWA/WISCONSIN....

...SUMMARY...
Isolated to scattered strong to severe thunderstorms are possible
from the upper Great Lakes into the central High Plains. Wind is the
primary risk, though hail is expected across portions of the High
Plains.

...Eastern KS/Western MO...
An overnight MCS is slowly weakening over central MO, with an
associated outflow boundary extending from eastern KS into
south-central MO. Strong heating will occur along and south of the
boundary, where several 12z CAM solutions indicate development of
afternoon thunderstorms. Given this scenario, have extended the
SLGT risk farther south into this region. Locally damaging wind
gusts would be the main concern. Refer to MCD #1506 for further
short-term details.

...WY/CO/SD/NE...
A low-amplitude shortwave trough is digging into WY. As forcing
associated with this system overspreads the High Plains of WY,
high-based convection is expected. Thunderstorms will intensify as
they track into a moderately unstable air mass and weak but backed
low-level flow. Severe storms capable of large hail and damaging
winds may affect the Black Hills region and southward into the NE
Panhandle.

Storms will also develop southward into the foothills of CO this
afternoon and spread eastward. Winds and temperatures aloft are
less favorable for organized/severe storms that far south, but at
least isolated instances of large hail and damaging winds are
possible.

...IA/WI...
Strong heating is occurring across much of WI today, where a moist
air mass will lead to moderate CAPE values. Thunderstorms will
develop by mid-afternoon along a remnant weak boundary across
central WI/northeast IA and spread northeastward through the day.
Vertical shear is not particularly strong, and overall convective
organization is expected to be low. Nevertheless, steep low-level
lapse rates and ample instability will promote strong downdrafts and
some hail in the strongest cells.

..Hart/Marsh.. 06/29/2025

$$

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ACUS01 KWNS 292002
SWODY1
SPC AC 292000

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Sun Jun 29 2025

Valid 292000Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
CENTRAL PLAINS INTO THE MIDDLE MISSISSIPPI VALLEY...AND OVER PARTS
OF THE UPPER MIDWEST...

...SUMMARY...
Isolated to scattered strong to severe thunderstorms are possible
from the upper Great Lakes into the central High Plains. Wind is the
primary risk, though hail is expected across portions of the High
Plains.

...20Z Update...
The Slight risk was expanded southeastward from parts of the central
Plains into the Middle MS Valley, where a cluster of thunderstorms
is intensifying as it impinges on a strongly unstable air mass. The
primary concern with this activity is damaging wind gusts. For
information on the severe risk here, reference Severe Thunderstorm
Watch 478. Additionally, 2-percent tornado probabilities were added
along this corridor and westward into southeast/south-central KS and
far northeast/north-central OK. Here, antecedent outflow is
diurnally destabilizing amid rich boundary-layer moisture.
Clockwise-curved low-level hodographs will support a localized
tornado risk with any cells that can develop in this corridor.

Farther west, significant-wind probabilities were added over
northwest KS, southwest NE, and far eastern CO. Any thunderstorm
clusters that evolve out of CO and move through this area will have
the potential of producing gusts upward of 75 mph -- aided by steep
deep-layer lapse rates and sufficiently elongated hodographs.
Additionally, visible satellite imagery shows a shallow
boundary-layer cumulus field along a surface wind shift in this
general area. As storms move into this area of enhanced moisture and
steep lapse rates, a brief tornado will be possible.

Reference Severe Thunderstorm Watch 477 and MCD 1508 for the severe
risk in the Upper Midwest, and MCDs 1509 and 1510 for the High
Plains severe risk.

..Weinman.. 06/29/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Jun 29 2025/

...Eastern KS/Western MO...
An overnight MCS is slowly weakening over central MO, with an
associated outflow boundary extending from eastern KS into
south-central MO. Strong heating will occur along and south of the
boundary, where several 12z CAM solutions indicate development of
afternoon thunderstorms. Given this scenario, have extended the
SLGT risk farther south into this region. Locally damaging wind
gusts would be the main concern. Refer to MCD #1506 for further
short-term details.

...WY/CO/SD/NE...
A low-amplitude shortwave trough is digging into WY. As forcing
associated with this system overspreads the High Plains of WY,
high-based convection is expected. Thunderstorms will intensify as
they track into a moderately unstable air mass and weak but backed
low-level flow. Severe storms capable of large hail and damaging
winds may affect the Black Hills region and southward into the NE
Panhandle.

Storms will also develop southward into the foothills of CO this
afternoon and spread eastward. Winds and temperatures aloft are
less favorable for organized/severe storms that far south, but at
least isolated instances of large hail and damaging winds are
possible.

...IA/WI...
Strong heating is occurring across much of WI today, where a moist
air mass will lead to moderate CAPE values. Thunderstorms will
develop by mid-afternoon along a remnant weak boundary across
central WI/northeast IA and spread northeastward through the day.
Vertical shear is not particularly strong, and overall convective
organization is expected to be low. Nevertheless, steep low-level
lapse rates and ample instability will promote strong downdrafts and
some hail in the strongest cells.

$$

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ACUS01 KWNS 300058
SWODY1
SPC AC 300056

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0756 PM CDT Sun Jun 29 2025

Valid 300100Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
HIGH PLAINS TO THE OZARKS...

...SUMMARY...
Scattered strong to severe thunderstorms remain possible this
evening across the central/Southern Plains and Ozarks. More
isolated severe storms are possible across the Great lakes and upper
Midwest. Wind is the primary risk, though hail is expected across
portions of the High Plains.

...Central High Plains...
Several clusters of severe storms are ongoing from southern SD to
eastern WY/CO and into western KS/NE. Moderate instability and
elongated hodographs will continue to support supercells. Hail and
damaging winds will remain likely this evening.

With time, upscale growth into one or more larger clusters appears
likely across the eastern CO Plains and western NE/KS. Modest
forcing for ascent and effective shear suggest the degree of
organization of any clusters that form is somewhat uncertain.
Confidence in greater storm organization is highest across parts of
KS/NE along the sagging cold front. Here, large buoyancy and locally
stronger forcing may allow for more efficient upscale growth. Should
a more organized MCS develop, a conditional risk for gusts upward of
75 mph is possible across parts of the central Plains tonight.

...Ozarks to central KS...
An ongoing complex of thunderstorms with an established cold pool is
likely to persist into this evening amidst a very buoyant (4000 J/kg
MUCAPE) but weakly sheared air mass across the Ozarks and southern
Plains. Model guidance and observational trends suggest a gradual
weakening of the entire complex is likely with southward extent this
evening, related to the loss of diurnal heating and the lack of
broader deep-layer ascent. Still, isolated damaging gusts remain
possible across northern AR and southern MO.

To the west, new thunderstorm development across parts of
south-central KS and northeastern OK will likely be the new focus
for stronger storms on the flanks of the surging outflow tonight.
Given the degree of buoyancy, isolated damaging gusts and some hail
are possible. One or more clusters of strong to occasionally severe
storms are likely, and may persist into northern OK and southern KS
tonight.

...Great Lakes to the upper Midwest...
Isolated storm development remains possible this evening along
trailing outflow and a weak cold front from southern WI to IA.
Vertical shear is not particularly strong, and overall convective
organization is expected to be low. Still, remaining instability
and moist surface conditions will promote occasional strong
downdrafts this evening.

..Lyons.. 06/30/2025

$$

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ACUS01 KWNS 300602
SWODY1
SPC AC 300600

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Mon Jun 30 2025

Valid 301200Z - 011200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN PLAINS MIDWEST AND MID ATLANTIC AS WELL AS THE NORTHWEST...

...SUMMARY...
Scattered strong to severe thunderstorms remain possible across
parts of the southern Plains, Ohio Valley, Midwest and the
Mid-Atlantic today. A couple of severe thunderstorms also cannot be
ruled out over parts of the Pacific Northwest.

...Synopsis...
A broad upper trough is forecast to intensify as it moves
southeastward across the Great Lakes and Midwest through tonight. At
the same time, sub-tropical ridging will build over the Plains,
keeping stronger flow aloft displaced to the north. To the west of
the ridge, an upper low will overspread portions of the West Coast.
At the surface, a weak cold front will sag southward from the
Midwest to the southern Plains. Numerous thunderstorms are likely
ahead of the front with isolated damaging gusts and hail possible.

...Midwest and Great lakes...
Ahead of the slow-moving cold front, rich low-level moisture with
dewpoints in the 70s F will be in place from MO/IL into Lower MI. A
messy surface pattern, with multiple remnant outflows and cloud
debris will likely modulate diurnal heating to some degree through
the early afternoon. With little inhibition, scattered to numerous thunderstorms are expected by mid afternoon as ascent from the
approaching upper trough overspreads the unstable air mass. Several
loosely organized bands or clusters of strong pulse storms are
likely. Weak mid-level flow and poor lapse rates suggests minimal
potential for greater storm organization. Though high PWATS near 2
inches will support heavy water loading and microburst potential,
with the stronger storms.

...OH valley to the Mid Atlantic...
A similar pattern to the Midwest, with somewhat higher storm
coverage, is expected from OH eastward into PA and the Mid Atlantic.
Scattered to numerous thunderstorms should develop by late morning
amid strong surface heating ahead of a subtle shortwave trough over
the OH valley. 20-30 kt of mid-level flow could support some
clustering of storms by early afternoon. Despite mediocre mid-level
lapse rates less than 6 C/km, the high PWAT air mass and some
consolidation of outflows could support isolated damaging wind
potential across eastern OH, southern NY into PA and the Mid
Atlantic states.

...Southern Plains to the Ozarks...
Scattered thunderstorms should develop by mid afternoon ahead of
sagging cold front from the TX Panhandle across the southern Plains
and western Ozarks. Beneath the northern fringes of the building sub
tropical high, strong heating and rich boundary-layer moisture will
support large buoyancy (MLCAPE (3000-4000 J/kg). Scattered
thunderstorm development is likely ahead of the front, and along
remnant outflows from overnight convection. Despite modest vertical
wind shear, the large buoyancy may still support occasional strong
to severe storms with the primary risk of damaging gusts and
occasional hail.

...Northern CA into southern OR...
Ahead of the weak upper low over southern CA, southerly flow will
aid in increasing mid-level moisture across parts of northern CA and
southern OR. Ample heating, weak synoptic ascent and typical
terrain-induced circulations will encourage scattered high-based
thunderstorm development through the afternoon. Nearly dry adiabatic
lapse rates from deep mixing of the boundary layer to near 500mb
will favor strong downdrafts capable of isolated severe wind gusts.
MUCAPE (~1000 J/kg) and 20-30 kt of southerly shear, may also
support marginally severe hail with the strongest cores.

..Lyons/Darrow.. 06/30/2025

$$

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ACUS01 KWNS 301250
SWODY1
SPC AC 301248

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Mon Jun 30 2025

Valid 301300Z - 011200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN PLAINS INTO THE MIDWEST AND MID ATLANTIC STATES...AND PARTS
OF THE DESERT SOUTHWEST AND WEST COAST...

...SUMMARY...
Isolated severe thunderstorms are possible across portions of the
southern Plains into the Midwest and the Mid-Atlantic, and in parts
of the Desert Southwest, and also in adjacent parts of southern
Oregon and northern California today.

...Synopsis...
Water-vapor imagery this morning shows an upper trough over the
Dakotas/Upper Midwest, and this feature is forecast to move into the
Great Lakes by tonight. At the same time, sub-tropical ridging will
build over the Plains, keeping stronger flow aloft displaced to the
north. Farther west, an upper trough/low will meander slowly
eastward over the eastern Pacific towards the CA coast. At the
surface, a weak cold front will sag southward from the
Midwest to the southern Plains.

...Southern Plains into the Midwest and Mid-Atlantic states...
A myriad of prior convective outflow in addition to the cold front
will serve as foci for storm development today. Ahead of the
slow-moving cold front, rich low-level moisture and heating will
lead to moderate to strong destabilization in areas void of
persistent early day cloud debris. Small clusters and bands of
storms may locally concentrate some damaging-wind threat, but
predictability of these meso-beta corridors remains uncertain.
Nonetheless, scattered storms will gradually progress east and
southward during the day and through the evening across the Marginal
Risk area. Strong to severe downdrafts will be the primary severe
threat, but large hail may occur with a few storms over parts of the
southern Plains where lapse rates/buoyancy are greater than areas
farther northeast. The overall severe threat will likely remain
tempered by weak to modest mid-level flow.

...Southwest NM and far southeast AZ...
Strong heating of an adequately moist airmass will result in
appreciable buoyancy by peak heating. Scattered thunderstorms
developing within an environment characterized by very steep lapse
rates and inverted-v profiles, will support isolated severe gusts
(60-70 mph) with the stronger evaporatively cooled downdrafts during
the late afternoon and early evening.

...Northern CA into southern OR...
Ahead of the weak upper trough immediately west of the CA coast,
southerly flow will aid in increasing mid-level moisture across
parts of northern CA and southern OR. Ample heating coupled with
weak large-scale and orographic ascent will aid in isolated to
scattered high-based thunderstorm development. Very steep lapse
rates and a deep, dry sub cloud layer will favor evaporatively
cooled downdrafts capable of isolated 55-65 mph gusts.

..Smith/Broyles.. 06/30/2025

$$

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ACUS01 KWNS 301629
SWODY1
SPC AC 301628

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1128 AM CDT Mon Jun 30 2025

Valid 301630Z - 011200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN PLAINS INTO THE MIDWEST AND MID ATLANTIC STATES...AND PARTS
OF THE DESERT SOUTHWEST AND WEST COAST...

...SUMMARY...
Isolated severe thunderstorms are possible across portions of the
southern Plains into the Midwest and the Mid-Atlantic, and in parts
of the Desert Southwest, and also in adjacent parts of southern
Oregon and northern California today.

...Southern OK/Northwest TX...
Morning visible satellite imagery confirms an outflow boundary
extending across central OK. Strong heating to the south of the
boundary will lead to a very unstable air mass with dewpoints in the
mid 70s and MLCAPE values over 3000 J/kg. Scattered thunderstorms
are expected to develop along the boundary by mid-afternoon,
propagating southward into north TX during the evening. Winds aloft
are rather weak in this area, suggesting limited storm organization.
However, the degree of instability and steep low-level lapse rates
will promote a risk of damaging wind in the stronger cells. Hail
will also be possible in the strongest updrafts.

...PA/NY...
A warm and humid air mass is present once again across parts of
NY/PA, where daytime heating will lead to MLCAPE values of 1500-2000
J/kg. Forecast soundings suggest ample mid-level moisture which
will be favorable for considerable coverage of storms, but may limit
the overall severe downdraft potential. Nevertheless, a few strong
to severe cells capable of locally damaging wind gusts are possible.
Refer to MCD #1522 for further details.

...NM/Southeast AZ...
Upper 40s and 50s dewpoints have become established across the
mountains of southern NM into southeast AZ. Full heating will lead
to deep mixing and inverted-v profiles over the region. Scattered
afternoon thunderstorms will likely result in gusty/damaging wind
gusts in some of this activity.

...Upper MI/WI...
A progressive shortwave trough over northern MN will track into the
Great Lakes region today, with cooling mid-level temperatures and
increasing large scale forcing. This will lead to scattered
late-afternoon thunderstorms over parts of WI and the Upper MI.
Locally gusty winds and hail are possible in these storms.

...Northern CA/Southern OR...
Ahead of the weak upper trough immediately west of the CA coast,
southerly flow will aid in increasing mid-level moisture across
parts of northern CA and southern OR. Ample heating coupled with
weak large-scale and orographic ascent will aid in isolated to
scattered high-based thunderstorm development. Very steep lapse
rates will pose a risk of gusty/damaging winds.

..Hart/Karstens.. 06/30/2025

$$

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ACUS01 KWNS 302004
SWODY1
SPC AC 302002

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0302 PM CDT Mon Jun 30 2025

Valid 302000Z - 011200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN PLAINS INTO THE MIDWEST AND MID ATLANTIC STATES...AND PARTS
OF THE DESERT SOUTHWEST AND WEST COAST...

...SUMMARY...
Isolated severe thunderstorms are possible across portions of the
southern Plains into the Midwest and the Mid-Atlantic, and in parts
of the Desert Southwest, and also in adjacent parts of southern
Oregon and northern California today.

...20Z Update...
Forecast scenario remains unchanged. See active Mesoscale
Discussions and the prior Outlook discussion below.

..Guyer.. 06/30/2025

.PREV DISCUSSION... /ISSUED 1128 AM CDT Mon Jun 30 2025/

...Southern OK/Northwest TX...
Morning visible satellite imagery confirms an outflow boundary
extending across central OK. Strong heating to the south of the
boundary will lead to a very unstable air mass with dewpoints in the
mid 70s and MLCAPE values over 3000 J/kg. Scattered thunderstorms
are expected to develop along the boundary by mid-afternoon,
propagating southward into north TX during the evening. Winds aloft
are rather weak in this area, suggesting limited storm organization.
However, the degree of instability and steep low-level lapse rates
will promote a risk of damaging wind in the stronger cells. Hail
will also be possible in the strongest updrafts.

...PA/NY...
A warm and humid air mass is present once again across parts of
NY/PA, where daytime heating will lead to MLCAPE values of 1500-2000
J/kg. Forecast soundings suggest ample mid-level moisture which
will be favorable for considerable coverage of storms, but may limit
the overall severe downdraft potential. Nevertheless, a few strong
to severe cells capable of locally damaging wind gusts are possible.
Refer to MCD #1522 for further details.

...NM/Southeast AZ...
Upper 40s and 50s dewpoints have become established across the
mountains of southern NM into southeast AZ. Full heating will lead
to deep mixing and inverted-v profiles over the region. Scattered
afternoon thunderstorms will likely result in gusty/damaging wind
gusts in some of this activity.

...Upper MI/WI...
A progressive shortwave trough over northern MN will track into the
Great Lakes region today, with cooling mid-level temperatures and
increasing large scale forcing. This will lead to scattered
late-afternoon thunderstorms over parts of WI and the Upper MI.
Locally gusty winds and hail are possible in these storms.

...Northern CA/Southern OR...
Ahead of the weak upper trough immediately west of the CA coast,
southerly flow will aid in increasing mid-level moisture across
parts of northern CA and southern OR. Ample heating coupled with
weak large-scale and orographic ascent will aid in isolated to
scattered high-based thunderstorm development. Very steep lapse
rates will pose a risk of gusty/damaging winds.

$$

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ACUS01 KWNS 010043
SWODY1
SPC AC 010042

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0742 PM CDT Mon Jun 30 2025

Valid 010100Z - 011200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE MIDDLE ATLANTIC...RED RIVER REGION OF THE SOUTHERN
PLAINS...SOUTHWESTERN BORDER AREA...AND PACIFIC NORTHWEST...

...SUMMARY...
Isolated strong, to locally severe, thunderstorms will persist for a
few hours this evening. Damaging gusts are the primary concern.

...01z Update...

Diurnal heating, and steepening of the boundary layer, has been the
primary instigator for scattered convection across much of the CONUS
this afternoon. Many areas have been efficiently overturned and with
onset of nocturnal cooling, further stabilization is expected this
evening. Even so, for the next few hours a few pockets of robust
convection will likely persist. Moderate to strong buoyancy is noted
across the Delmarva and the Red River region of southern OK/north
TX. Deep convection may continue to generate locally strong winds
until this activity weakens by mid evening.

Isolated wind gusts may also accompany high-based convection across
southeast AZ/southern NM, and near the OR/CA border. Boundary-layer
cooling will also contribute to further weakening, along with a
lessening severe threat.

..Darrow.. 07/01/2025

$$

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ACUS01 KWNS 010549
SWODY1
SPC AC 010548

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1248 AM CDT Tue Jul 01 2025

Valid 011200Z - 021200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDDLE
ATLANTIC REGION...

...SUMMARY...
Scattered strong to severe storms are possible across parts of the
Mid-Atlantic into the Northeast this afternoon/evening. An isolated
severe storm may also occur over parts of the High Plains.

...Middle Atlantic...

Upper trough currently located over the upper Great Lakes, extending
into central MO, is forecast to shift into the OH Valley by late
afternoon before advancing across the northern/central Appalachians
by the end of the period. At the surface, a cold front will progress
into the upper OH Valley early in the period and this will serve as
the focus for scattered thunderstorms by mid day.

Early this morning, water-vapor imagery suggests a weak
low-amplitude short-wave trough is embedded within the base of the
larger trough along the IL/IN border. Radar data supports this with
a few clusters of thunderstorms extending from western IN into
western TN. Current speed/movement of this feature would place this
short wave into southern OH/eastern KY by 18z. While low-level lapse
rates are not forecast to be that steep across the Middle Atlantic,
modest southwesterly mid-level flow will contribute to adequate
shear, supporting organized line segments/clusters. Current thinking
is scattered thunderstorms will readily develop ahead of this
feature, and a marked increase in convection should be noted into
the mid afternoon across southern PA into northern VA. Latest HREF
guidance supports this scenario, and forecast soundings favor
damaging winds with convection that develops within a high-PW air
mass, despite marginal lapse rates/instability. Strong-severe
convection should spread off the Middle Atlantic Coast during the
evening.

...High Plains...

A weak short-wave trough appears to be topping the Rockies ridge
over eastern ID/southern MT early this morning. This feature will
begin to dig southeast toward the Black Hills, eventually migrating
into the lower MO Valley by the end of the period. As a result, a
weak lee trough should extend across eastern WY during the late
afternoon and isolated thunderstorms are expected to develop across
the High Plains of western SD into the NE Panhandle/northeast CO.
Some consideration was given to a SLGT Risk across this region but
activity may prove too sparse to warrant higher severe
probabilities. Even so, wind profiles suggest a few slow-moving
supercells could develop. With LLJ expected to strengthen across
this region after sunset, this would favor a few longer-lived
storms. If it appears coverage will be a bit more expansive then
currently forecast, a SLGT Risk may be warranted.

..Darrow/Halbert.. 07/01/2025

$$

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