SPC AC 241203

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0703 AM CDT Mon May 24 2021

   Valid 241300Z - 251200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTRAL GREAT
   PLAINS TO THE SOUTHERN HIGH PLAINS...

   ...SUMMARY...
   Scattered severe hail and wind are possible, mainly from
   mid-afternoon through this evening, over parts of the central Great
   Plains into the southern High Plains.

   ...Central Great Plains to Upper Midwest...
   A stalling surface front will effectively act more as a dryline at
   peak heating with warmer surface temperatures west of the boundary
   in the Upper Midwest due to deeper mixing. A shortwave impulse near
   the UT/WY/CO border will eject northeast into the Upper Midwest by
   evening. The bulk of stronger mid-level southwesterlies will largely
   parallel and remain confined to the dry side of the front. But
   sufficient deep-layer shear will exist in vicinity of the front to
   support a mixed mode of multicell clusters with embedded supercells,
   as scattered thunderstorms develop during the mid to late afternoon.
   These will likely be most pronounced across western KS and perhaps
   into the Mid-MO Valley where a moderately unstable air mass is
   expected by peak heating with MLCAPE reaching 1500-2000 J/kg.
   Scattered severe hail and wind will be the primary hazards. Some
   guidance indicates additional storms will initiate overnight from
   eastern CO into northwest KS within a zone of increasing isentropic
   ascent north of the front. Some of this activity may also produce
   large hail and locally strong winds. 

   ...Southern High Plains...
   Scattered thunderstorms will develop across the higher terrain of
   the TX Trans-Pecos and north along the dryline from southeast NM
   into the western OK/TX Panhandle on the western periphery of upper
   50s to low 60s surface dew points. While moderate buoyancy with
   MLCAPE of 1500-2000 J/kg amid steep mid-level lapse rates is
   expected, flow aloft will remain relatively weak across the region. 
   Given the modest deep-layer shear, multicells eventually evolving
   into slow-moving multicell clusters will be the primary storm modes.
   Isolated to perhaps scattered severe wind gusts along with isolated
   large hail will be the main hazards.

   ...Central VA and eastern WV...
   Backdoor surface front will become situated from the central
   Appalachians through VA into NC during the afternoon where dew
   points in the low 60s F will reside. Diabatic warming of the surface
   layer will contribute to destabilization and inverted-V low-level
   thermodynamic profiles, but weak mid-level lapse rates should limit
   MLCAPE to near or below 500 J/kg. A few thunderstorms should develop
   over the higher terrain within the modest northwest flow regime.
   Some of this activity might become capable of producing locally
   damaging winds.

   ..Grams/Mosier.. 05/24/2021

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