FOUS30 KWBC 032002
QPFERD
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
402 PM EDT Fri Apr 3 2026
Day 1
Valid 16Z Fri Apr 03 2026 - 12Z Sat Apr 04 2026
...THERE IS SLIGHT RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS INTO THE OZARKS, MISSOURI VALLEY, AND UPPER
MISSISSIPPI VALLEY...
...16Z update...
The forecast remains on track, only small edits were needed to
account for QPF trends. Convection is already underway near the
triple point in the Midwest and should ignite this afternoon ahead
of and along the cold front over the Plains. The best potential for
flash flooding remains across North Texas and central and eastern
Oklahoma where the low level jet and frontal dynamics will be
favorable for training/repeating storms and with the potential for
high rainfall rates exceeding 2 inches per hour. A Slight Risk
remains in effect for this activity and encompasses areas that are
expected to receive 3-5 inch rainfall totals, with locally higher
amounts possible. A Slight Risk also remains in effect from
eastern Iowa into far northwestern Illinois and far southwestern
Wisconsin where strong storms in the vicinity of the triple point
low will produce heavy rainfall on top of relatively moist soils.
There is potential for 3-5 inch rainfall totals in this area, and
scattered instances of flash flooding could be a possibility.
Dolan
...Previous Discussion...
At the mid-levels, a stout wave over the Intermountain West
(centered over Wyoming) will migrate eastward throughout the day,
spreading increasingly strong mid-level flow and height falls from
the High Plains eastward toward the Mid/Upper Mississippi Valley.
At the surface, strong 850mb flow and poleward flux of
moisture/instability will become established along and ahead of a
low initially across the Kansas/Nebraska border region at the
beginning of the forecast period and persist through 12Z Sat. Late
in the forecast period, a cold front will migrate southward across
the southern Plains. Areas of scattered thunderstorms are expected
along and ahead the front and low especially during the afternoon
and evening, with several areas of flash flooding expected.
The primary area for flash flood potential will exist along the
OK/TX Red River vicinity southward toward central Texas and the Big
Country. Scattered thunderstorms are expected to develop during
the afternoon and evening across the region, with CAMs suggestive
of training/repeating behavior and local areas of 2-5 inch totals.
The glancing influence of the aforementioned mid-level wave across
the region lends some doubt on degree and location of
daytime/afternoon convective coverage, which should modulate the
flash flood risk substantially.
Even if convection materializes as depicted by CAMs, antecedent
dryness of ground conditions are a mitigating factor for a more
widespread or significant flash flood risk. Persistent training
will likely be needed for ground conditions to lose receptiveness
to rainfall on a widespread basis. Both pre-frontal convection and
convection moving in along a surface cold front late represent two
distinct regimes for heavy rain and flash flood potential - with
that risk eventually spreading toward I-35 in Texas and the DFW
Metroplex area through early Saturday.
Farther north, convection along the front will likely sweep through
portions of Missouri and Oklahoma, with a greater risk/potential
for multiple mergers and/or convective clusters with southward
extent. Areas just southeast of Kansas City received copious
amounts of rain Thursday and will probably not have fully recovered
before the incoming thunderstorm threat through early Saturday,
necessitating maintenance of Slight Risk probabilities there.
Lastly, models (primarily CAMs) depict potential for
repeating/training convection across portions of northeastern Iowa
and vicinity through much of the day (from 16-18Z through well into
the evening) along/near a surface warm front and well ahead of an eastward-moving cold front that should reach the area late in the
forecast period. NASA Sport soil moistures suggests slightly more
moist ground conditions in these areas, and the advance of the
mid-level wave and confluence on the northern end of strong 850mb
flow all point to prolonged deep convective potential. 3-5 inch
totals cannot be ruled out in this regime. A Slight Risk has been
added to the outlook in these areas as a result.
Though less widespread, additional convection should traverse wet
ground conditions across portions of Ohio, Pennsylvania, and
southern New York State, supporting continued Marginal
probabilities in that area.
Cook
Day 2
Valid 12Z Sat Apr 04 2026 - 12Z Sun Apr 05 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE ARKLATEX AND THE LOWER MISSISSIPPI VALLEY...
Much of convective evolution during the D2/Sat forecast period=20
will depend on convective details from lingering convection across=20
Arkansas and Texas left over from D1/Fri. East-northeastward=20
progression of a mid-level wave toward the Great Lakes will aid in=20 southeastward movement of a cold front from the Plains through the=20 Ozarks/Mid-Mississippi Valley during the forecast period. This=20
front will gradually become more parallel to weakening flow aloft=20
from Texas to Mississippi, supporting additional opportunities for=20
training convection as storms organize along remnant outflows and=20
backbuild, with the potential for areal average rainfall in the=20
1-2" range leading to isolated instances of flash flooding.=20
A more focused threat has been identified supporting the=20
introduction of two Slight Risk areas within the broader Marginal=20
Risk. The first is across portions of the ArkLaTex southwest=20
through northeast Texas. The latest hi-res guidance supports the=20
maintenance of ongoing convection within the Slight Risk for the=20
day 1 period across Oklahoma continuing southeastward along the=20
front into Saturday morning. A wave of low pressure along the front
in northeast Texas will also help to maintain/enhance the=20
development of this convection as well as briefly slow the=20
progression of the front northeast through the ArkLaTex, allowing=20
for heavier rainfall totals as storms persist over the region for a
longer amount of time before the front begins to sweep southward=20
faster later into the afternoon. The latest 12Z CAMs show the=20
potential for locally heavy totals of 3-4" with rain rates of=20
2-2.5" per hour. The second region is across portions of the Lower=20 Mississippi Valley later in the day where moist southerly flow from
the Gulf will bring a pool of ~70 degree dewpoints northward.=20
These high dewpoints along with daytime heating will lead to a=20
region of 1000-2000 J/KG CAPE supporting the development of heavy-
rainfall producing thunderstorms ahead of the front. The=20
combination of this initial development in addition to a second=20
round of storms expected along the front with similarly high rain=20
rates of ~2" per hour will also lead to the potential of locally=20
heavier totals in the 3-4" range. While dry antecedent=20
conditions/high FFGs may limit the overall threat, the potential=20
for these higher rain rates/totals within the highlighted Slight=20
Risks should be sufficient enough for at least a localized/urban=20
scattered flash flood threat.
Farther north, convection is likely to be progressive across much=20
of the Lower Ohio Valley along with potential for inhibited=20
destabilization due to more widespread convection across the Lower=20 Mississippi Valley. Too much uncertainty exists to reduce the=20
Marginal Risk area at this time. Notable exceptions to this general
regime exist, however, from northern Ohio into southern New York=20
State and Pennsylvania, where models suggest appreciable daytime=20
heating and moderate instability developing. Storms may not be all=20
that fast moving either in Pennsylvania as that region should=20
reside on the southern extent of stronger mid-level flow into=20
southeastern Canada. Convective coverage is a bit uncertain, but=20
any greater-than-anticipated coverage of convection in this=20
environment could locally raise flash flood concerns - especially=20
with low FFGs noted across that area.
Putnam/Cook
Day 3
Valid 12Z Sun Apr 05 2026 - 12Z Mon Apr 06 2026
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
SOUTH TEXAS ON SUNDAY...
...20Z Update...
The latest model guidance supports the prior forecast reasoning=20
with the potential for isolated heavy rainfall-producing storms as=20
moisture pools along the frontal boundary. There is some concern=20
that the front will be progressive enough that moisture/CAPE will=20
be swept out of south Texas before the start of the period limiting
any threat, but at least for now guidance retains at least some=20
potential. This is particularly true closer to the Gulf Coast=20
portion of the risk area where a surface wave and slower=20
progression of the front into the Gulf further east may keep the=20
front along the south Texas coast long enough to lead to some=20
storms.
Putnam
...Previous Discussion...
Maintained the Marginal Risk of Excessive rainfall area that was=20
introduced by the WPC Medium Range desk as a west- to- east=20
oriented front makes its way southward. Deeper moisture should be=20
pooling along and south of the boundary with precipitable water=20
values around 1.75 inches in place at the start of the outlook=20
period.
Given uncertainties detailed in the Day 2 period with respect to=20
the timing and placement...combined with the 03/00Z NCEP global=20
models now showing the front to be more progressive than in earlier
runs which led to CAPE being swept out of South Texas faster...was
not inclined to introduce a Slight Risk area at this point. At the
same point...spaghetti plots from the non-CAM ensembles still show
enough members with 1 inch QPF and a few contours of 2 inch QPF to
support keeping the Marginal area with only minor nudges around=20
the periphery.
Bann
Day 1 threat area:
https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!70Ixmd4yAaWGBEMXRxNRUMw8_PCKY-RLHMFwCljbyD0F= 9rZ70lD1J9E35v6Uv9ZHcLvAou-ndXpXRb8e_Kr7hW8rNN8$=20
Day 2 threat area:
https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!70Ixmd4yAaWGBEMXRxNRUMw8_PCKY-RLHMFwCljbyD0F= 9rZ70lD1J9E35v6Uv9ZHcLvAou-ndXpXRb8e_Kr76yHCIZk$=20
Day 3 threat area:
https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!70Ixmd4yAaWGBEMXRxNRUMw8_PCKY-RLHMFwCljbyD0F= 9rZ70lD1J9E35v6Uv9ZHcLvAou-ndXpXRb8e_Kr7-K5nWIo$=20
=3D =3D =3D
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