ACUS11 KWNS 230020
SWOMCD
SPC MCD 230020=20
SDZ000-NEZ000-KSZ000-COZ000-NDZ000-MTZ000-WYZ000-230145-

Mesoscale Discussion 1265
NWS Storm Prediction Center Norman OK
0720 PM CDT Mon Jun 22 2026

Areas affected...the High Plains of Southeast Montana into northeast
Colorado

Concerning...Severe Thunderstorm Watch 376...377...

Valid 230020Z - 230145Z

The severe weather threat for Severe Thunderstorm Watch 376, 377
continues.

SUMMARY...Isolated severe thunderstorms continue across portions of
the central and northern High Plains. Large to very large hail and
isolated severe wind gusts will be possible this afternoon/evening.
A couple of tornadoes will also be possible near the Colorado,
Wyoming, Nebraska border.

DISCUSSION...Isolated supercells continue across the northern and
central High Plains this afternoon. These supercells are moving
south-southeast in an environment characterized by MUCAPE values in
excess of 2000 J/kg and effective-layer shear greater than 40 knots.
These supercells have a history of producing very large hail (up to
3" in diameter across northeast Colorado and the Nebraska
Panhandle), significant severe thunderstorm winds (a 109 mph wind
gust measured recently near Akron, CO), and tornadoes.

The low-level environment features fairly large temperature-dewpoint
spreads (on the order of 20-30F) and relatively high cloud bases
with the ongoing supercells. And while the overall low-level wind
field is fairly weak, the area across northeast Colorado into
southeast Wyoming and the adjacent parts of the Nebraska Panhandle
are located to the north of the Denver Cyclone, which has yielded a
more easterly component to the low-level wind field and slightly
greater curvature in the low-level hodograph. With the relatively
slow movement of the supercells, and their east-west orientation,
the low-level moisture field is likely being locally modified by the supercells' forward flank, resulting in lower LCL heights than the
ambient environment might otherwise suggest. When these localized
lower LCL heights combine with the slightly greater low-level
helicity across this localized area, a slightly greater tornado
threat has evolved, with several supercells producing tornadoes.

The primary threat over the next few hours should remain large hail,
with periodic severe-to-significantly severe wind gusts. However, a
couple tornadoes will remain possible, especially across the
aforementioned area of northeast Colorado, southeast Wyoming, and
the adjacent parts of the Nebraska Panhandle.

..Marsh.. 06/23/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!6G4Hcg5T3Yu-NJ32fEedlPw2ZkJMZLzf4pi_r8MKe0LxEIBulKwcBU936cmCZlOmJggwhH7Jj= dbxK9OCUsFfh_npRsE$ for graphic product...

ATTN...WFO...BIS...LBF...UNR...GLD...BOU...CYS...BYZ...GGW...
RIW...

LAT...LON 39730181 39530256 39620351 41130464 42340549 45640821
46850758 46720396 44660393 44560189 43750197 43650302
39730181=20

MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
MOST PROBABLE PEAK WIND GUST...75-90 MPH
MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN


=3D =3D =3D
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