US Mesoscale Discussions

Storm Prediction Center Mesoscale Discussion 1358

   Mesoscale Discussion 1358
   NWS Storm Prediction Center Norman OK
   0156 PM CDT Fri Jun 21 2024

   Areas affected...Central and Eastern Wyoming...into far Southern

   Concerning...Severe potential...Watch likely 

   Valid 211856Z - 212100Z

   Probability of Watch Issuance...95 percent

   SUMMARY...Weather watch issuance may be needed within the next
   couple of hours as storm coverage increases over the high terrain of
   W WY, with additional development happening further east along the
   Laramie range in SE WY. Primary expected hazards are for damaging
   winds and hail.

   DISCUSSION...Thunderstorm coverage has increased over W WY beneath a
   broad upper trough, with surface temperatures warming into the
   mid-to-upper 70s F out ahead in Central WY. Dewpoints in the
   mid-to-upper 50s F have spread northward along the front range of
   the Rockies in Eastern WY as lee troughing beneath the upper wave
   continues, with some dewpoints in the upper 40s to low 50s F
   reaching into Central WY. This warm/moist boundary-layer air,
   coupled with steep mid-level lapse rates of 8-9 C/km, has resulted
   in SPC Mesoanalysis MLCAPE values of 1000-1500 J/kg. This buoyancy
   is colocated with deep layer shear values in the 40-50 kt range,
   indicating organized multicell clusters and supercells are possible.

   As daytime heating and moisture transport continues out ahead of
   developing convection, combinations of buoyancy and shear will
   continue to support a supercell threat. Primarily straight-line
   hodographs over W WY should support splitting supercells, and
   coupled with abundant storm coverage, indicates the potential for
   plentiful thunderstorm and outflow interactions that result in
   primarily a damaging wind and hail threat. However, a brief tornado
   cannot be ruled out in SE WY, where surface winds are locally backed
   to the east. Additionally, RAP forecast profiles in NE WY show
   potential for locally backed flow and curved hodographs later this
   evening, though uncertainty in overall storm coverage and mode may
   preclude a more robust tornado threat. Overall, the eastward extent
   of severe hazards appears to be limited due to convective inhibition
   increasing during the afternoon and evening, largely due to
   subsidence behind a 500mb vort max exiting NE CO/SW NE. 

   Severe thunderstorm watch issuance is expected between 19-20Z,
   primarily for 70 MPH winds and 2 inch hail.

   ..Halbert/Weinman/Hart.. 06/21/2024

   ...Please see for graphic product...


   LAT...LON   44550824 44840831 45220818 45450778 45450727 45480675
               45450604 45410525 45270477 45010433 44650407 44370397
               43930387 43500387 43130387 42610387 42160396 41730409
               41520431 41290464 41150537 41250624 41650679 42220712
               42730746 43030763 43350775 43740788 44140802 44550824 

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