Mesoscale Discussion 1467
   NWS Storm Prediction Center Norman OK
   0659 PM CDT Tue Aug 11 2020

   Areas affected...southwestern North Dakota...western South
   Dakota...and far southeast Montana

   Concerning...Severe potential...Watch possible 

   Valid 112359Z - 120200Z

   Probability of Watch Issuance...60 percent

   SUMMARY...Storms developing over southeastern Montana/southwestern
   North Dakota vicinity may increase in coverage -- and possibly grow
   upscale -- over the next few hours.  Resulting severe potential --
   mainly in the form of damaging winds -- could warrant WW issuance.

   DISCUSSION...Latest radar loop shows isolated thunderstorms
   continuing to develop in the southeastern Montana vicinity, near the
   northwestern fringe of an axis of moderate instability (1500 to 3000
   J/kg mixed-layer CAPE) lying northwest to southeast across South
   Dakota.  The storms appear to be initiating in the vicinity of a
   northern High Plains lee trough, and with ample instability but
   dewpoint depressions of 40 to 50 degrees F indicative of the deep
   mixed layer that exists, locally damaging wind gusts will likely
   accompany the stronger storms (along with large hail potential).

   With time, as a low-level jet develops this evening, the resulting
   increase in warm advection -- combined with the aforementioned axis
   of favorable instability -- may support some degree of upscale
   growth, into an east-southeastward-moving MCS.  Such evolution would
   result in greater/more widespread potential for wind damage -- which
   warrants WW consideration across this area.

   ..Goss/Thompson.. 08/11/2020

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

   ATTN...WFO...ABR...BIS...UNR...BYZ...

   LAT...LON   45780491 46230449 46530321 45500054 44060111 43720254
               44550409 45780491