SPC AC 160734

   Day 3 Convective Outlook CORR 1
   NWS Storm Prediction Center Norman OK
   0234 AM CDT Tue Mar 16 2021

   Valid 181200Z - 191200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS EXTENDING FROM
   GEORGIA NORTHWARD ACROSS THE CAROLINAS...

   CORRECTED TO INCLUDE SIG AREA IN PROB GRAPHIC

   ...SUMMARY...
   Severe weather is expected from southern Virginia southward into
   Florida, and westward into portions of eastern Kentucky/eastern
   Tennessee Thursday.  Along with potential for hail and locally
   damaging winds, several tornadoes -- a couple of them possibly
   strong -- are anticipated.

   ...Synopsis...
   A vigorous upper low initially progged over eastern portions of the
   Ozarks, is expected to continue steady eastward progression through
   the period, weakening gradually as it crosses the Appalachians and
   reaches Virginia/the Carolinas by the end of the period.  In the
   wake of this feature, ridging will expand to encompass much of the
   country, as an eastern Pacific trough nears the Pacific Northwest
   Coast late.

   As the upper system advances, a surface low just ahead of cyclone
   aloft will likewise progress eastward, crossing the mountains during
   the evening before redeveloping offshore through the end of the
   period.  A trailing cold front will cross the southern Appalachians
   through the first half of the period, before moving offshore
   overnight.  A second day of fairly widespread -- and possibly
   locally substantial -- severe risk is anticipated.

   ...Parts of the Mid and Southern Atlantic Coast states, and westward
   into eastern parts of KY/TN...
   Showers and thunderstorms -- and some attendant severe weather risk
   -- will be ongoing Thursday morning, particularly over the southern
   Appalachians region.  With associated clouds streaming northeastward
   across the  middle and southern Atlantic Coast states, hindered
   heating -- and thus tempered diurnal destabilization -- is expected.
    Still, with northward advection of higher theta-e air east of the
   mountains ahead of the advancing surface system causing a rapid
   retreat of the remnant damming front, sufficient CAPE should evolve
   to support vigorous storms -- with intensity of the updrafts aided
   by strongly veering/increasing flow with height.  

   Storms should increase through midday west of the mountains across
   parts of eastern Kentucky/eastern Tennessee ahead of the synoptic
   system.  Relatively low-topped storms -- and local risk for
   all-hazards severe weather -- will likely evolve.

   Meanwhile, storms are expected to spread across Georgia and into the
   Carolinas ahead of the advancing cold front, along with some
   pre-frontal cellular development within a zone of strong warm
   advection east of the mountains.  Given ample instability and a very
   favorably sheared environment, relatively widespread and locally
   substantial severe weather potential is indicated -- including risk
   for a few strong tornadoes.  Potential is expected to expand
   northward toward/into southern Virginia with time as the front
   retreats into the evening, before convection begins to end from west
   to east as the cold front moves toward -- and eventually off -- the
   Atlantic Coast.

   ..Goss.. 03/16/2021

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