ACUS11 KWNS 280010
SWOMCD
SPC MCD 280010=20
NEZ000-SDZ000-COZ000-280145-

Mesoscale Discussion 1358
NWS Storm Prediction Center Norman OK
0710 PM CDT Sat Jun 27 2026

Areas affected...portions of southwestern South Dakota into the
Nebraska Panhandle

Concerning...Tornado and Severe Thunderstorm Watches 406...407...

Valid 280010Z - 280145Z

The severe weather threat for Tornado and Severe Thunderstorm
Watches 406, 407 continues.

SUMMARY...Isolated to widely scattered convection continues to pose
a risk for primarily large hail and damaging wind gusts.

DISCUSSION...Isolated to widely scattered supercells have developed
across far southwestern South Dakota and northwestern Nebraska as of
2350 UTC to the west of a diffuse dryline. In the near-term, the
primary risk associated with this convection will be large to very
large hail (perhaps to 2.5+ inches in diameter) given strong
effective shear, elongated hodographs, and ample buoyancy within the
hail growth zone (as supported by SHIP values ranging form 1-3+ per
latest objective analysis). Recent high-res guidance and regional
radar imagery suggest that rapid upscale growth may occur with the
ongoing convection across southwestern South Dakota, which would
favor a transition towards damaging/severe wind gusts as the primary
risk. Farther south, ongoing convection is likely to remain more
isolated within the Nebraska Panhandle, with large to very large
hail and damaging wind gusts being possible with supercells.
Additional development farther south into southwestern Nebraska
remains uncertain at this time.

Some increase in tornado potential may occur with time and as
convection progresses eastward given greater moisture to the east of
the diffuse dryline and a strengthening nocturnal low-level jet that
will yield increasingly clockwise-curved low-level hodographs. A
more linear storm mode and greater convective inhibition/capping to
the east of the dryline lend uncertainty to the magnitude of the
tornado risk, however. The greatest risk for a tornado is likely to
occur with any discrete supercell that can persist farther east into
this evening.

..Chalmers.. 06/28/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!-r07C___aaepEXEpNYpGNJjI7rVVVM-X0sTlIhnE-LYHa7Xho07SbvpkQhSBoLIMjG85L90ox= gIf6rBkre-t8W7QQIs$ for graphic product...

ATTN...WFO...LBF...UNR...BOU...CYS...

LAT...LON 42850344 43350333 44010309 44450267 44570214 44510176
44290145 43770139 42630136 41790140 41220147 40990164
40850201 40800247 41030294 41680332 42170338 42850344=20

MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN


=3D =3D =3D
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* Origin: Capitol City Weather Station (1:2320/127)