SPC AC 170608

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0108 AM CDT Wed Mar 17 2021

   Valid 181200Z - 191200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM CENTRAL AND
   EASTERN GEORGIA NORTHEASTWARD ACROSS PARTS OF CENTRAL AND EASTERN
   NORTH CAROLINA...

   ...SUMMARY...
   A widespread/substantial severe weather event is expected to
   continue into Thursday from southern Virginia southward into
   Florida, and westward into portions of eastern Kentucky/eastern
   Tennessee.  Along with potential for widespread damaging winds and
   hail, several tornadoes -- a few of them likely to be strong -- are
   anticipated.

   ...Synopsis...
   An upper low initially forecast over the Ozarks area is expected to
   shift steadily eastward through the period, reaching the Mid South
   by evening and then crossing the Appalachians and evolving into a
   more open wave overnight.  Meanwhile in the west, an eastern Pacific
   upper low/trough should approach the West Coast overnight.

   At the surface, a low initially progged over the southern Illinois
   area will cross the Ohio Valley through the day.  By evening, the
   low should reside in the central Appalachians area, and then is
   expected to elongate across the Mid Atlantic region overnight as
   weak offshore low development commences.  A cold front trailing from
   the low -- bisecting the Mid South and extending south to the
   western Florida Panhandle -- should clear the crest of the
   Appalachians during the early evening, before continuing eastward to
   move off the East Coast overnight.  Meanwhile, a remnant damming
   front will shift quickly northward as a warm front across the
   Atlantic Coast states, allowing a warm sector to spread northward
   into Virginia ahead of the advancing low.

   ...Eastern KY/TN east to the Chesapeake Bay, and south to FL...
   Showers and thunderstorms are forecast to be ongoing in an elongated
   zone of warm advection from Missouri east across the Ohio Valley
   states and into the Mid Atlantic region, and more significantly --
   from eastern Tennessee and possibly eastern Kentucky, southward
   across western Georgia, southeastern Alabama, and the Florida
   Panhandle. Ongoing/all-hazards severe risk is expected to accompany
   the convection -- primarily across the northern/western Georgia
   vicinity.

   With time, continued northward moistening/theta-e advection ahead of
   the approaching system will result in a broad warm sector east of
   the Appalachian crest, and secondarily -- across parts of eastern
   Kentucky and southern Ohio into West Virginia/western Virginia. 
   Though heating may be tempered into the afternoon in many areas due
   to downstream cloud debris from ongoing convection, around 1000 J/kg
   mixed-layer CAPE should become widespread across the warm sector.

   The increasingly moist/unstable environment will support a
   continuation of the ongoing storms within a loose band ahead of the
   cold front, which will spread across Georgia and the Carolinas, and
   eventually southern Virginia, with some potential for
   isolated/cellular development ahead of this convective band.  Cells
   may also develop in the wake of an initial convective band northward
   into western North Carolina, while storms also develop into the
   afternoon west of the mountains into southern Ohio/western
   Kentucky/west Virginia.  The storms west of the mountains will
   likely become locally severe, with hail and damaging winds the
   primary risk, though a tornado or two would be possible.

   Farther south and east -- into eastern Georgia and the Carolinas,
   and spreading north into parts of southern Virginia, very strong
   flow aloft, veering -- and increasing substantially in magnitude
   with height through the lower troposphere -- will result in shear
   quite favorable for supercells.  Along with hail potential, the more
   substantial risk will be from widespread damaging winds, as well as
   tornadoes -- including possibility for a few strong/significant
   tornadoes during the afternoon and into the early evening.  Threat
   will gradually taper from west to east, as the system shifts
   eastward and the cold front eventually moves offshore.

   ..Goss.. 03/17/2021

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