Mesoscale Discussion 1021
   NWS Storm Prediction Center Norman OK
   0628 PM CDT Fri Jun 07 2019

   Areas affected...southeast MT...northwest SD...southwest ND

   Concerning...Severe Thunderstorm Watch 340...

   Valid 072328Z - 080100Z

   The severe weather threat for Severe Thunderstorm Watch 340
   continues.

   SUMMARY...The severe risk is beginning to ramp up for areas over
   northwest SD and southwest ND.  Severe gusts (60-75mph) and large
   hail (1-2 inches in diameter) are the threats with the stronger
   storms.

   DISCUSSION...Water-vapor imagery shows a potent mid-level shortwave
   trough moving through the Northern Rockies and northern
   InterMountain regions early this evening.  Farther east over the
   western Dakotas and southeast MT, the initial plume of 700-500mb
   ascent will overspread this area during the next 1-2 hours according
   to objective analyses.  

   Surface analysis via observations and radar fine-line data indicate
   a cold front is slowly pushing east across central ND with the
   boundary stalling near the Black Hills.  Surface dewpoints in the
   middle 50s are located over southwest ND into northwest SD.  It
   appears most of the ongoing thunderstorm activity moving into the
   western Dakotas is preferentially favoring the cool-side of the
   boundary where shallow frontal lift is more supportive for storm
   development compared to a capped warm sector farther east.  

   Some short-term convection-allowing model guidance is suggestive
   that the ongoing storms over southeast MT and the area along the
   SD/WY border is the initial evolution of a severe-wind producing
   cluster of thunderstorms expected to move northeast across southwest
   ND/northwest SD and eventually into central ND later this evening. 
   A new severe thunderstorm watch will likely be needed farther
   northeast of severe thunderstorm watch 340.  However, during the
   next 1-2 hours, the expectation is for a gradual intensification of
   storms over southeast MT moving into the western Dakotas with the
   risk for severe gusts coincidentally increasing.

   ..Smith.. 06/07/2019

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

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

   LAT...LON   46590405 46710295 46360212 45910176 44180322 44220373
               45420525 45820539 46590405