Mesoscale Discussion 0775
   NWS Storm Prediction Center Norman OK
   0335 PM CDT Sun May 31 2020

   Areas affected...northeast Wyoming...southeast Montana...southwest
   North Dakota...and northwest South Dakota.

   Concerning...Severe potential...Watch possible 

   Valid 312035Z - 312230Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Thunderstorm development is probable in the next few
   hours, and storms that do form will pose the threat for severe wind
   and hail. A watch is possible if sustained, mature convection can
   become established.

   DISCUSSION...Recent visible satellite imagery shows a growing region
   of agitated cumulus developing off of the Big Horn mountains in
   northern WY. Thunderstorm development is likely within the next hour
   in this region given sufficient MLCAPE values (500-1000 J/kg) and
   favorable deep layer shear (30-40 knots of effective bulk shear).
   Continued daytime heating and modest low-level moisture advection
   across southeast Montana ahead of these storms should continue to
   favorably modify the thermodynamic environment by reducing MLCIN and
   somewhat augmenting MLCAPE. Given 7-9 C/km lapse rates and a dry,
   well-mixed boundary within the lowest 1-2 km, strong to severe
   downburst winds will be possible with the stronger storms. As
   discrete to semi-discrete storms move into the MT/SD/ND tri-state
   region, they should encounter higher instability that will continue
   to support strong winds as well as the potential for severe hail. 

   The main uncertainty with this activity is storm coverage. Weak
   forcing for ascent and lingering inhibition over southern/southwest
   MT may limit the number of mature storms that will develop over
   southwest MT/northern WY and casts some doubt into the overall
   severe threat. Trends will be monitored and a watch is possible if
   mature convection can become established as it moves towards the
   tri-state area.

   ..Moore/Grams.. 05/31/2020

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

   ATTN...WFO...BIS...UNR...BYZ...GGW...RIW...

   LAT...LON   45040801 46030807 46720723 47270625 47530457 47320378
               46760321 46010306 45060303 44840337 44470460 44360751
               45040801