SPC AC 210515

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1215 AM CDT Tue Aug 21 2018

   Valid 221200Z - 231200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF NEW ENGLAND...THE COASTAL CAROLINAS/MID-ATLANTIC STATES AND
   SOUTH-CENTRAL HIGH PLAINS...

   ...SUMMARY...
   Isolated strong to severe thunderstorms may occur Wednesday across
   portions of the coastal Carolinas/southeast Virginia and the
   south-central High Plains.

   ...Synopsis...
   Cyclonic flow aloft will persist across the majority of eastern
   CONUS as a series of shortwave troughs move through the OH Valley
   and Northeast States. Surface low attendant to the lead shortwave
   trough will likely be centered over southern Quebec at the beginning
   of the period, with a cold front extending southward through central
   NY/PA then southwestward into the Carolina Piedmont. 

   Farther east, upper ridging will remain centered over the southern
   Plains while shortwave ridging moves across the northern Plains and
   upper Midwest ahead of a shortwave trough moving through the
   northern Rockies and northern High Plains.

   ...Portions of New England...
   Latest guidance suggests the cold front will move eastward
   throughout the day, reaching eastern portions of New England during
   the late morning/early afternoon. Moist profiles and widespread
   cloudiness will limit destabilization but somewhat warmer and more
   moist air will likely advect into the region just ahead of the
   approaching cold front. Resulting modest instability will aid in the
   development of scattered thunderstorms along and/or just ahead of
   the cold front. Vertical shear is strong enough to support isolated
   severe potential within any of the more persistent updrafts.

   ...Coastal Carolinas/Mid-Atlantic States...
   Frontal position/timing and antecedent precipitation will play a
   large role in modulating the severe potential across this region on
   Wednesday. Current guidance indicates the cold front will likely
   extend from the southern Delmarva Peninsula southwestward into
   southeast GA. This frontal position would leave 70 dewpoints and
   moderate instability in place across a southeast VA and the eastern
   Carolinas. While there is some displacement between the better flow
   aloft (north) and the stronger instability (south), enough overlap
   exists to support the potential for a few severe storms from the
   late morning into the evening.

   ...South-Central High Plains...
   The region will be favorably placed along the northwestern periphery
   of the upper ridge centered over central TX and along the
   southwestern periphery of a surface high centered near the central
   NE/KS border. As a result, modest westerly flow aloft will exist
   atop moist, southeasterly upslope flow. Resulting vertical shear and
   instability will favor the potential for a few strong to severe
   storms as storms develop during the late afternoon and early
   evening.

   ...MAXIMUM RISK BY HAZARD...
   Tornado:   2%     - Marginal
   Wind:      5%     - Marginal
   Hail:      5%     - Marginal

   ..Mosier.. 08/21/2018

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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z