Storm Prediction Center Mesoscale Discussion 1960

   Mesoscale Discussion 1960
   NWS Storm Prediction Center Norman OK
   0705 PM CDT Mon Aug 19 2024

   Areas affected...western Montana and adjacent portions of Idaho

   Concerning...Severe Thunderstorm Watch 640...

   Valid 200005Z - 200200Z

   The severe weather threat for Severe Thunderstorm Watch 640
   continues.

   SUMMARY...Scattered strong thunderstorms moving northeastward across
   the western Montana vicinity remain capable of producing locally
   gusty/damaging outflow winds.

   DISCUSSION...Latest radar loop shows scattered thunderstorms moving
   northeastward across the western Montana vicinity, including a few
   embedded/stronger cells.  The storms are very high-based, with
   surface temperatures in convectively unperturbed areas in the low
   90s, and dewpoints in the 30s.  

   With the mixed layer extending to around 600 mb, and modest CAPE
   (around 500 J/kg) above, potential for substantial evaporatively
   driven downdraft acceleration is evident.  This suggests ongoing
   risk for locally damaging wind gusts as storms continue shifting
   across the area.  Eventually, diurnal cooling of the boundary layer
   will begin to hinder the severe risk, but until then, risk persists
   in/near WW 640.

   ..Goss.. 08/20/2024

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

   ATTN...WFO...BYZ...TFX...PIH...MSO...BOI...OTX...

   LAT...LON   48811460 48931353 48491164 47511027 46230952 45410976
               45061178 44631441 44751547 45631623 48811460