SPC AC 240600

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0100 AM CDT Thu Jun 24 2021

   Valid 241200Z - 251200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM A PORTION
   OF THE CENTRAL PLAINS INTO THE MIDDLE MISSISSIPPI VALLEY REGION...

   ...SUMMARY...
   Scattered strong to severe thunderstorms are expected across a broad
   region of the central Plains, Mid Mississippi Valley, and the upper
   Midwest on Thursday. The greatest threat including the potential for
   significant wind damage is forecast over the central Plains into the
   middle Mississippi Valley.

   ...Central Plains through middle Mississippi Valley...

   MCS currently over eastern NE continue into northern MO through the
   morning before weakening, likely posing an ongoing risk for damaging
   wind. The remnant outflow boundary should extend from central MO
   northwestward through northeast KS into eastern NE, and this feature
   will shift northeast during the day. Robust boundary-layer recovery
   and destabilization will likely occur in the vicinity of and west of
   this boundary as rich low-level moisture (low 70s F dewpoints)
   advects northeast along a southwesterly low-level jet. A cold front
   will likely move slowly southeast and should extend from the upper
   Midwest southwest through central and southwest NE, then northwest
   into the central High Plains. South of this feature, easterly
   low-level winds are expected north of a thermal low that will be
   situated over western KS. A dryline should extend southward from the
   thermal low into the southern High Plains. A corridor of richer
   low-level moisture will likely persist with the easterly low-level
   flow regime across northern KS into central and eastern NE. A warm
   elevated mixed layer with 8.5+ C/km mid-level lapse rates will
   persist across this region above the moist boundary layer
   contributing to MLCAPE from 3000-4000 J/kg. 

   Potential areas for thunderstorm initiation include the deeply mixed
   boundary layer across the central High Plains, along the dryline
   from the TX Panhandle into southwest KS and along/north of the
   outflow boundary across northeast KS into northwest MO and southeast
   NE. High-based storms that develop over western KS and southwest NE
   will likely intensify as they spread east and intercept the moist
   and unstable boundary layer across southern NE into northern KS.
   Vertical wind profiles with 40+ kt effective bulk shear will support
   supercells as the initial storm mode, but storms should eventually
   evolve into an organized MCS with potential for significant wind
   damage as it continues through the central Plains into the middle MS
   Valley during the afternoon and into the overnight. The best threat
   for a few tornadoes will be along and just to the cool side of the
   outflow boundary from northeast KS/northwest MO into southeast NE
   and southwestern IA, where 0-1 km hodographs will be the most
   supportive of low-level mesocyclones, especially with any discrete
   supercells that can develop during the afternoon or early evening.

   ...Upper Midwest and Great Lakes region...

   Thunderstorms are expected to develop along a cold front during the
   afternoon within an environment characterized by modest instability
   and 30-40 kt effective bulk shear. The stronger storms may produce a
   few locally strong to severe wind gusts and hail from afternoon into
   the early evening.

   ..Dial/Lyons.. 06/24/2021

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