Mesoscale Discussion 0682
   NWS Storm Prediction Center Norman OK
   0148 PM CDT Sat May 23 2020

   Areas affected...Southwest South Dakota...Eastern Wyoming...and the
   Nebraska Panhandle

   Concerning...Severe potential...Watch likely 

   Valid 231848Z - 232045Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Increasing thunderstorm coverage expected through the
   afternoon. Large hail (some very large) will be the primary threat
   with some severe wind gusts possible as well.

   DISCUSSION...Thunderstorms have been ongoing over the Black Hills
   for several hours late this morning and into the early afternoon.
   Relatively weak instability and a strong cap has limited updraft
   strength thus far, but instability is quickly increasing with MLCAPE
   above 1000 J/kg across the region and SPC mesoanalysis suggests CINH
   has mostly eroded. Temperatures are expected to warm into the upper
   70s which should yield afternoon MLCAPE around 1500 J/kg. Expect
   storms to form in the next 1 to 2 hours near the Black Hills and
   eastward where the cu field has expanded substantially early this
   afternoon. The KUDX VWP shows effective shear around 30 to 35 knots
   which will support a combination of multicells and supercells given
   the aforementioned instability. 

   Additional storms are expected to develop along the dryline and
   higher terrain in eastern Wyoming and move northeastward through the
   afternoon. Limited instability across eastern Wyoming may mostly
   limit the storm intensity initially before expected strengthening
   near the NE/SD border as they encounter greater instability. 

   Mid-level lapse rates around 8 C/km and storm mode will support
   large hail as the primary threat with the potential for very large
   hail, especially with any supercells that can remain discrete.
   However, severe winds will also be possible considering the well
   mixed sub-cloud layer supportive of downdraft acceleration.

   ..Bentley/Hart.. 05/23/2020

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

   ATTN...WFO...LBF...UNR...BOU...CYS...

   LAT...LON   44520471 44920408 45160328 45290265 45020191 43870195
               42650220 41820275 40930342 40890410 41140471 41620507
               42480546 44410482 44520471