SPC AC 280555

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1255 AM CDT Sun Mar 28 2021

   Valid 281200Z - 291200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS
   SOUTHEASTERN VIRGINIA AND ADJACENT FAR NORTHEAST NORTH CAROLINA...

   ...SUMMARY...
   Scattered severe storms are likely along an advancing cold front
   from the Mid-Atlantic into the Carolinas. The highest confidence in
   damaging winds is in southeastern Virginia and vicinity. Farther
   south and west, a few strong to severe storms are possible from
   Mississippi into Georgia.

   ...Synopsis...
   Shortwave trough currently extending from the Upper Midwest back
   southwestward through the central Plains will continue eastward
   throughout the day, moving through the Great Lakes, OH Valley,
   Mid-Atlantic and much of the Northeast. As it does, the system is
   expected to mature significantly, with both a deep surface low over
   southern Quebec and strong mid-level flow from the TN Valley into
   the Mid-Atlantic predicated by this afternoon. 

   A cold front will also accompany this system. Expectation is for
   this front to extend from western NY southwestward along the central
   and southern Appalachians by around 18Z this afternoon. The front is
   forecast to be off the Northeast and Mid-Atlantic coasts by 00Z
   Monday. A broad area of at severe potential will exist of this front
   from the northern Mid-Atlantic into the Southeast.

   ...Mid-Atlantic/Carolinas...
   Ongoing convective system over the TN and Lower MS Valleys is
   expected to continue eastward/northeastward this morning and into
   this afternoon. Most of the 00Z guidance is too slow with the
   forward progression of the system, particularly the portion entering
   middle TN, where more forward propagation has been noted. While some
   slowing of convective line is likely has instability wanes with
   eastern extent, overall expectation is for this area of convection
   to reach central VA/NC this morning. 

   As such, severe potential across the region will be tied to the
   potential for re-development along the front. The bulk of the
   guidance suggests destabilization will occur ahead of the front, and
   that a strongly forced line will develop along the front. Intense
   low to mid-level flow will favorable strong, convectively enhanced
   wind gusts within this line. A few embedded tornadoes are possible
   as well. 

   Given this severe potential, 30% wind/5% probabilities will be
   maintained with this outlook. However, uncertainty regarding the
   stability of the air mass preceding the front merits close
   observation of overnight trends and guidance, with potential
   downgrades needed in subsequent outlooks. 

   ...Southeast...
   Modest buoyancy will continue to promote thunderstorm development
   along the front as it moves across the region this morning and into
   this afternoon. Low-level winds will likely veer before frontal
   passage and stronger flow aloft will be increasingly displaced
   north. However, the environment will remain conducive to
   occasionally organized storms capable of strong downbursts. A brief
   tornado or two could also occur within the line, particularly over
   northern GA where low-level flow is expected to remain strong as the
   line moves through.

   ..Mosier/Karstens.. 03/28/2021

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z