Mesoscale Discussion 1052
   NWS Storm Prediction Center Norman OK
   0344 PM CDT Mon Jun 29 2020

   Areas affected...northeast Wyoming...eastern Montana...western South
   and North Dakota,

   Concerning...Severe potential...Watch possible 

   Valid 292044Z - 292245Z

   Probability of Watch Issuance...60 percent

   SUMMARY...Isolated strong to severe thunderstorms are expected to
   develop over the northern High Plains by 22Z. Trends will continue
   to be monitored for a possible WW.

   DISCUSSION...As of mid afternoon a warm front extends from a surface
   low in far eastern MT through southwestern ND. A cold front extends
   southward from the low through southeast MT into southwest SD. The
   atmosphere in this region has become moderately to strongly unstable
   with surface dewpoints ranging from the upper 50s to mid 60s F.
   Further moist advection is expected into early evening beneath steep
   mid-level lapse rates supporting 1500-3000 J/kg MLCAPE. Visible
   imagery shows cumulus increasing near and east of triple point along
   the warm front, with additional towering cumulus over the black
   hills as well as the higher terrain of northeast WY. RAP analysis
   also show a weak vorticity maximum lifting northward through eastern
   WY. Though timing is somewhat uncertain, orographic forcing as well
   as convergence in vicinity of the triple point and warm front should
   result in thunderstorm initiation by 22Z. Vertical wind profiles
   with 30-40 kt effective bulk shear will support both multicell and
   some supercell structures with damaging wind and large hail the main
   threats. A window will exist for a couple of tornadoes, mainly near
   the warm front as low-level shear undergoes some increase during the
   early evening.

   ..Dial/Hart.. 06/29/2020

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

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

   LAT...LON   44370480 46100528 47160490 48390375 48650236 47730175
               45650279 43950310 43560378 44370480