Storm Prediction Center Mesoscale Discussion 1254

   Mesoscale Discussion 1254
   NWS Storm Prediction Center Norman OK
   0559 PM CDT Wed Jun 11 2025

   Areas affected...Parts of Wyoming into the Northern High Plains

   Concerning...Severe Thunderstorm Watch 409...

   Valid 112259Z - 120030Z

   The severe weather threat for Severe Thunderstorm Watch 409
   continues.

   SUMMARY...Isolated severe thunderstorms will continue this evening.

   DISCUSSION...High-level diffluent flow is noted across the northern
   Rockies ahead of a pronounced short-wave trough. Water-vapor imagery
   supports this with large-scale ascent spreading across southern MT
   into western WY. Scattered thunderstorms have developed across this
   region and several robust supercells have generated large hail at
   times, along with some gusty winds. 500mb speed max will translate
   across northern WY later this evening, and this may encourage
   additional development along a surface boundary draped along the
   eastern slopes of the Big Horn Mountains. If so, strong storms may
   advance downstream a bit farther than currently indicated by ww0409.

   ..Darrow.. 06/11/2025

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...UNR...BYZ...RIW...

   LAT...LON   43321039 45650714 45130498 43810570 42180897 43321039 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN