Mesoscale Discussion 0870
   NWS Storm Prediction Center Norman OK
   0204 PM CDT Sun Jun 07 2020

   Areas affected...central South Dakota into north central Nebraska

   Concerning...Severe potential...Watch likely 

   Valid 071904Z - 072100Z

   Probability of Watch Issuance...95 percent

   SUMMARY...Boundary-layer cumulus is beginning to increase across
   portions of central South Dakota and north central Nebraska. Severe
   thunderstorm development appears likely in the next few hours. A
   watch will likely be needed.

   DISCUSSION...18z regional analysis indicates that ascent from a
   shortwave trough embedded in the broader western US trough is
   beginning to overspread the northern and central Plains. At the
   surface, a 998 mb low is developing along a surface pressure trough
   across western South Dakota. Strong southerly winds have developed,
   with 30-40 mph gusts observed across Nebraska and southern South
   Dakota. 

   Two areas of increasingly agitated cumulus associated with strong
   surface heating and mixing have been noted across Nebraska and South
   Dakota. Surface dewpoints have also responded to the deeper mixing
   by decreasing, (likely due to the relatively shallow nature of the
   moisture), over the last few hours. Convective initiation appears
   probable in the next couple of hours with the decreasing inhibition
   and surface temperatures in the 90s F nearing convective
   temperature. 

   Proximity RAP soundings show 2000-3500 J/kg of MLCAPE overlain by
   40-50 kt of effective bulk shear. This should support a primarily
   supercellular mode with the initial storms. Hail and strong winds
   will be the main threats, though a tornado or two will be possible
   with the stronger discrete storms. There is uncertainty primarily in
   the longevity of the discrete convective mode, given relatively
   large temperature dewpoint spread approaching 25-30 F. Upscale
   growth, with an increasing wind damage threat, appears most likely.
   A watch will be needed in the next couple of hours.

   ..Lyons/Thompson.. 06/07/2020

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

   ATTN...WFO...FSD...ABR...LBF...UNR...

   LAT...LON   44130095 45870011 45899710 45519699 44749738 42729867
               41690001 41410068 41620104 44130095