ACUS11 KWNS 210028
SWOMCD
SPC MCD 210027=20
SDZ000-NEZ000-MTZ000-WYZ000-210200-

Mesoscale Discussion 1217
NWS Storm Prediction Center Norman OK
0727 PM CDT Sat Jun 20 2026

Areas affected...eastern Wyoming...western Nebraska
Panhandle...southwest South Dakota...and far southeast Montana

Concerning...Severe Thunderstorm Watch 356...

Valid 210027Z - 210200Z

The severe weather threat for Severe Thunderstorm Watch 356
continues.

SUMMARY...Thunderstorms with a history of measured severe winds will
weaken as the move northeast this evening. Although a few severe
wind gusts will be possible in the near term, the overall wind
threat will weaken with time. A new watch is currently not
anticipated.

DISCUSSION...An arc of convection across eastern Wyoming continues
to fan out as it moves east across the High Plains. These storms
have had a history of producing significant winds, with multiple
reports of winds in excess of 80 mph across Converse and Wright
counties.=20

The non-convectively modified airmass across eastern Wyoming
features steep low-to-mid-level lapse rates that have supported
downward momentum transfer and the subsequent strong winds as
convection moves into them. However, as the storms move farther
north and east, the airmass becomes increasingly unfavorable for
severe gusts as instability quickly decreases and low-level lapse
rates considerably weaken.

Given the ongoing storms and their recent history, the potential for
isolated severe wind gusts will continue in the near term. However, longer-term, the increasingly unfavorable environment should limit
downward momentum transfer and the overall severe potential. As
such, a downstream severe thunderstorm watch is currently not
anticipated.

..Marsh.. 06/21/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!9n72lyyZdu1bqhzQKsqS_wcN8lw5co-heRbdNUt66pexTGAf--iz36hRlUEyaR5NByrRzujYm= PJm6T4_hr54OHeWLtg$ for graphic product...

ATTN...WFO...LBF...UNR...CYS...BYZ...RIW...

LAT...LON 41600506 43500540 44230602 45110534 45200415 43490242
41570316 41600506=20

MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN


=3D =3D =3D
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