SPC AC 281249

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0749 AM CDT Sun Mar 28 2021

   Valid 281300Z - 291200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE MID-ATLANTIC STATES...

   ...SUMMARY...
   Scattered severe thunderstorms capable of wind damage and a couple
   of tornadoes are expected across the Carolinas and Mid-Atlantic
   States as well as parts of the Southeast today into this evening.

   ...North Carolina and Mid-Atlantic/coastal Northeast States...
   Thunderstorm-related wind damage is possible, along with a risk for
   brief tornadoes, mainly this afternoon through early evening.
   However, the overall forecast scenario is complex, with lingering
   uncertainties regarding the extent/magnitude of today's severe risk,
   particularly given the prevalence of early day cloud
   cover/convection across the region.

   Early today, a warm/moist conveyor focused in vicinity of a
   northward-shifting warm front is contributing to scattered
   thunderstorms across the coastal Mid-Atlantic including northeast
   North Carolina northward toward the Delmarva. Upstream, a spatially
   extensive convective line/composite outflow roughly parallels the
   spine of the Appalachians from along the West Virginia/Virginia
   border vicinity southwestward into northern Georgia. 

   Although additional boundary layer moistening will continue to occur
   within the broad warm sector, convective-line preceding cloud cover
   appears likely to temper diurnal destabilization in most areas into
   the afternoon. The most probable scenario appears to be for
   increasing linear convective organization east of the Blue Ridge and
   into the North Carolina Piedmont this afternoon in vicinity of the
   eastward-advancing cold front. Boundary layer destabilization should
   remain weak, particularly outside of the North Carolina coastal
   plain and southeast Virginia, but an organizing/intensifying
   convective line will be supported by increasing forcing for ascent
   and cyclogenesis in vicinity of the lower Great Lakes. This linearly
   organized/fast-moving convection will likely overspread
   central/eastern portions of North Carolina and Virginia, along with
   the Delmarva, and potentially as far north as southern New
   York/southern New England through late afternoon/early evening. 

   Even where surface-based destabilization is minimal, very strong
   deep-layer winds, accentuated by 50-65 kt southwesterly winds within
   the lowest 1-3 km AGL, will support the possibility of convectively
   related wind damage, and possibly some line-embedded circulations
   capable of relatively brief tornadoes this afternoon into evening.

   ...Southeast States including South Carolina/Georgia/Alabama...
   A semi-broken/quasi-linear cluster of storms may continue to pose an
   isolated severe risk this morning from central/eastern Alabama into
   western/northern Georgia and western South Carolina. These storms
   may tend to outpace the more appreciable moistening/destabilization
   from the southwest, while low-level winds will otherwise continue to
   veer over time. Isolated wind damage will remain possible early
   today, and potentially remain possible this afternoon into other
   parts of Georgia/South Carolina pending downstream destabilization
   and the disposition of the early day convective line.

   ..Guyer/Kerr.. 03/28/2021

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