SPC AC 040543

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1243 AM CDT Mon May 04 2020

   Valid 041200Z - 051200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN
   OKLAHOMA INTO EXTREME SOUTHEAST KANSAS AND SOUTHEST MISSOURI...

   ...SUMMARY...
   Severe thunderstorms are possible today across portions of eastern
   Kansas/Oklahoma into western Tennessee. Very large hail, in excess
   of 2-3 inches, may accompany thunderstorms from eastern Oklahoma
   into southwestern Missouri. Some damaging wind threat and a couple
   of tornadoes can also be expected.

   ...Central/Southern Plains to western KY/TN...

   500mb speed max is forecast to translate across CO early in the
   period before shifting into the mid-MS Valley by early evening.
   Associated short-wave trough will suppress the height field north of
   I-40 and a notable surface cold front should surge south across the
   central Plains to a position arcing from southeast KS - central OK -
   TX South Plains by 05/00z. Prior to the short wave, surface warm
   front, currently draped near the Red River, should lift north
   allowing upper 60s-70F surface dew points to return across much of
   eastern OK into southeast KS. Additionally, intense surface heating
   will occur across the southern High Plains which will allow
   temperatures to soar through the upper 90s into the lower 100Fs west
   of the dry line.

   Prior to this development, strong elevated convection may be noted
   early in the period ahead of the short-wave trough across northern
   KS. Substantial mid-level buoyancy and strong shear appear
   supportive of elevated supercells and hail may accompany this
   activity. Large-scale forcing for ascent will likely contribute to
   further elevated severe spreading/developing east-southeast along a
   ribbon of focused low-level warm advection. Late-evening CAMs
   support a corridor of elevated supercells spreading from northern KS
   into central MO, and this seems reasonable given the warm front
   orientation.

   While hail should be common with these elevated storms, intense
   boundary-layer heating across southwestern OK will allow surface
   parcels to reach their convective temperatures along the dry line by
   22z. Latest NAM forecast soundings exhibit extreme MLCAPE (>5000
   J/kg) ahead of the front and east of the dry line across OK. While
   pre-frontal low-level flow should be somewhat veered, frontal
   convergence will be more than adequate for thunderstorm initiation
   given the negligible inhibition by 22z. Very large hail can be
   expected with supercells during the late afternoon into the early
   evening and early in the convective cycle. A couple of tornadoes may
   also be noted. However, damaging-wind threat should increase as
   early discrete activity becomes more linear in nature with possible
   bow-type structures evolving, as this activity builds south and
   propagates southeast toward north-central TX during the late
   evening. For these reasons, have increased hail probabilities across
   portions of eastern OK into southeast KS.

   ..Darrow/Squitieri.. 05/04/2020

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