SPC AC 310545

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1245 AM CDT Wed Mar 31 2021

   Valid 311200Z - 011200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER THE SOUTHEAST
   AND THE CENTRAL CAROLINAS...

   ...SUMMARY...
   Organized severe thunderstorms are possible on Wednesday across
   portions of the Southeast, with damaging gusts the primary severe
   threat. More isolated severe storms are also possible across parts
   of the Mid Atlantic, with the severe threat potentially continuing
   after dark.

   ...Synopsis...
   Upper trough currently covering much of the western and central
   CONUS will continue eastward throughout the day, traversing the MS
   Valley and ending the day extended from the Upper Great
   Lakes/southwestern Ontario through the TN Valley and central
   Southeast States. Strong mid-level flow will accompany this system,
   with 90+ kt at 500 mb from the TN Valley into the central
   Appalachians late Wednesday evening. 

   Cold front associated with this upper trough will likely extend from
   a low over middle TN southwestward to the middle Rio Grande Valley
   later this morning. Expectation is for this front to make continual
   eastward/southeastward progress throughout the day. By this evening
   (00Z/Thursday), the surface low will likely be centered near the
   Chesapeake Bay with the front extending southwestward along the
   Piedmont and through the western FL Panhandle. Showers and
   thunderstorms are expected along the length of this front, with at
   least low severe potential from the Mid-Atlantic through the Lower
   MS Valley. 

   ...Southeast...
   Showers and thunderstorms are expected to gradually increase along
   the front this morning, with development of a fairly coherent line
   of storms through the early morning. Boundary-parallel shear vectors
   will continue to promote a linear storm mode with occasional strong
   wind gusts possible. The air mass downstream is forecast to become
   increasingly unstable, both as a result of filtered daytime heating
   and increasing boundary layer moisture. Resulting increase in
   buoyancy coupled with steep low-level lapse rates is expected to
   result in a more organized linear structure/stronger outflow capable
   of damaging wind gusts. Low-level flow is also forecast to be strong
   enough to support brief line-embedded/QLCS tornadoes, particularly
   across southern AL. 

   ...Carolinas/Mid-Atlantic...
   Low-level moisture advection ahead of the approaching cold
   front/upper trough is expected to bring low 60s dewpoints as far
   north as the Delmarva Peninsula. Whether or not higher dewpoints can
   be maintained farther south across southeast VA and Carolina will
   depend on the strength/depth of the mixing anticipated amidst the
   southwesterly downslope flow. This low-level should result in modest
   air mass destabilization, with thunderstorms anticipated along the
   front as it moves through. At least moderate flow will exist
   throughout much of the low to mid-levels, contributing to the
   potential for damaging wind gusts.

   Pre-frontal, warm sector storms are also possible across the
   central/eastern Carolinas as the air mass destabilizes. However,
   updraft depth and persistence with these storms will likely be
   limited, owing to relatively warm temperatures aloft and
   displacement east of the better low and mid-level flow.

   ..Mosier/Moore.. 03/31/2021

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