SPC AC 280826

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0226 AM CST Sat Nov 28 2020

   Valid 301200Z - 011200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   FLORIDA/COASTAL GEORGIA INTO THE CAROLINAS AND MID-ATLANTIC...

   ...SUMMARY...
   Isolated strong to severe thunderstorms capable of producing
   damaging winds and perhaps a couple of tornadoes appear possible on
   Monday from parts of Florida and coastal Georgia into the Carolinas
   and Mid-Atlantic.

   ...Florida/Coastal Georgia into the Carolinas and Mid-Atlantic...
   A large-scale upper trough should evolve into a closed low over the
   Midwest/OH Valley and central Appalachians on Monday. A mid-level
   vorticity maximum embedded within this upper trough is forecast to
   move quickly northeastward from the central Appalachians into the
   Mid-Atlantic through Monday afternoon. A deep surface low should
   likewise develop northeastward in tandem with this vorticity
   maximum. A cold front trailing from this surface low will likely
   sweep eastward across much of the FL Peninsula and the East Coast
   through the day. A warm front extending northeastward from the
   surface low will probably make some northward progress across parts
   of the Mid-Atlantic through Monday afternoon as well.

   A line of low-topped showers/storms along or just ahead of the cold
   front should be ongoing at the start of the period from near the
   surface low in WV/western VA southward to northern FL. Although
   instability may remain modest across most of the warm sector ahead
   of this line, generally low to mid 60s surface dewpoints should be
   enough to support weak surface-based instability through the day. A
   very strong (50-60+ kt) south-southwesterly low-level jet should be
   present over the central/eastern Carolinas and southern VA Monday
   morning, and this feature is forecast to shift northward across the
   Mid-Atlantic through the day. 

   Given the strength of the low-level flow and sufficient, albeit
   weak, forecast instability, strong to damaging winds may occur with
   storms that either persist along the cold front or develop ahead of
   it over the open warm sector. A couple tornadoes also appear
   possible, mainly across parts of eastern SC/NC/VA to the Delmarva
   Peninsula and perhaps NJ in associated with the low-level jet and
   potentially greater low-level moisture and instability. Even so,
   there is too much uncertainty regarding sufficient destabilization
   to include higher severe probabilities for now.

   Farther south, low-level convergence along the cold front and
   deep-layer shear are both forecast to be somewhat weaker across
   coastal GA and the FL Peninsula. Still, there may be isolated
   strong/gusty winds with any storms through Monday afternoon.

   ..Gleason.. 11/28/2020

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