SPC AC 311950

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0250 PM CDT Wed Mar 31 2021

   Valid 312000Z - 011200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
   THE SOUTHEAST...

   ...SUMMARY...
   Scattered damaging winds, marginally severe hail, and perhaps a
   brief tornado will remain possible across portions of the Southeast
   States into the Mid Atlantic through this evening.

   ...20Z Update...
   Primary changes to the outlook were to clear areas of thunder/severe
   probabilities behind the cold front, mainly across the Southeast.
   Along and ahead of the front across the Southeast, convection has
   organized into a line, with embedded cells propagating from roughly
   west-to-east along the line. Some of these cells have promoted
   occasional damaging gusts and marginally severe hail over the last
   couple of hours. Strong diurnal heating ahead of the current line of
   storms has fostered 1200-1500 J/kg MLCAPE amidst 40-50 kts of
   effective bulk shear, suggesting that a damaging gust/marginally
   severe hail threat should continue through the rest of the
   afternoon. Please see MCD #0310 for more details. 

   Across the Carolina Piedmont, adequate diurnal heating has allowed
   temperatures to warm into the 80s, with low to mid 60s dewpoints
   contributing to 500-1000 J/kg MLCAPE. Current visible satellite
   indicates deep moist convection initiating, with a few lightning
   flashes recently noted. Latest high resolution guidance depicts a
   gradual increase in convective coverage and intensity, with a couple
   instances of damaging gusts, marginally severe hail and perhaps a
   brief tornado still possible. Please see MCS #0309 for more details.

   ..Squitieri.. 03/31/2021

   .PREV DISCUSSION... /ISSUED 1127 AM CDT Wed Mar 31 2021/

   ...Central Gulf Coast to AL/GA...
   A convective swath is ongoing from north GA west-southwest to
   central LA with deeper embedded cores near the MS/AL border area,
   along a southeast-moving cold front. Weak mid-level lapse rates
   sampled by area 12Z soundings will be a limiting factor to
   instability, but low-level destabilization is underway with
   warm-sector cloud breaks. This will likely support an increasingly
   expansive plume of modest buoyancy (MLCAPE of 500-1500 J/kg) from
   the Lower MS Valley towards the AL/GA border, and contribute to an
   uptick in convective intensity through this afternoon. Embedded
   bowing segments will be possible as boundary-parallel shear vectors
   favor a quasi-linear storm mode. Scattered damaging winds are likely
   to be the most common threat, but a brief tornado is possible.

   ...Carolinas...
   An MCV in northwest GA should track along the lee of the southern
   Appalachians along composite outflow from downstream showers across
   the western Carolinas. This will aid in potential for organized
   clusters and a QLCS during the late afternoon to early evening.
   These clusters/QLCS should develop as the MCV impinges on a
   destabilizing air mass across the Piedmont, supported by
   boundary-layer heating amid a plume of upper 60s surface dew points
   emanating north from the South Atlantic Coastal Plain. While
   mid-level lapse rates will remain weak, MLCAPE of 500-1500 J/kg
   should become common. With convective activity expected to outpace
   movement of the surface cold front, the region should largely lie
   along the eastern periphery of stronger mid-level southwesterlies.
   With 30-35 kt effective shear, scattered damaging winds should be
   the primary hazard, but a brief tornado is possible.

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