Mesoscale Discussion 1576
   NWS Storm Prediction Center Norman OK
   0648 PM CDT Tue Aug 25 2020

   Areas affected...Parts of southwestern through south central Montana

   Concerning...Severe potential...Watch unlikely 

   Valid 252348Z - 260145Z

   Probability of Watch Issuance...5 percent

   SUMMARY...Thunderstorms accompanied by strong to locally severe wind
   gusts will likely be maintained east-northeast of the mountains of
   southwestern Montana, through areas of south central Montana between
   Billings and Lewistown by 7-8 PM MDT.

   DISCUSSION...Aided by forcing for ascent associated with one of
   several subtle short wave perturbations, migrating around the
   northwestern periphery of prominent mid-level subtropical riding, at
   least a couple of clusters of thunderstorms appear to be merging
   with consolidating outflow.  This is now approaching the White
   Sulphur Springs and Bozeman vicinities, embedded within 30-40 kt
   deep-layer west-southwesterly mean ambient flow.  Associated
   moderately strong deep-layer shear is contributing to convective
   organization, which seems likely to persist at least into evening. 
   Although a deeply mixed downstream boundary layer appears only
   weakly unstable, in terms of CAPE, steep lower/mid tropospheric
   lapse rates with large sub-cloud temperature/dew point spreads
   likely will remain supportive of a continuing risk for strong to
   locally severe wind gusts.  This will progress across the higher
   terrain, through the Musselshell Basin vicinity by 02-03Z.

   ..Kerr/Grams.. 08/25/2020

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

   ATTN...WFO...BYZ...GGW...TFX...MSO...

   LAT...LON   45571288 46571126 47150904 47070705 46040711 45531021
               44981219 45571288