SPC AC 210730

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0230 AM CDT Fri Aug 21 2020

   Valid 231200Z - 241200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF THE NORTH-CENTRAL U.S....AS WELL AS OVER PARTS OF THE
   NORTHEAST...

   ...SUMMARY...
   A few strong/locally severe storms will be possible over portions of
   the northern Plains vicinity, and parts of northern New York into
   New England.

   ...The Dakotas and Nebraska Panhandle vicinity...
   Short-wave troughing moving through the westerly flow field aloft is
   expected to reach the northern Plains during the afternoon, with a
   weak/accompanying surface low expected to cross the region as well. 
   Modest afternoon destabilization, combined with focused ascent near
   the low, should result in isolated afternoon storm development,
   which could increase in coverage into the evening as a southerly
   low-level jet develops.  Given moderate westerlies aloft atop
   low-level southerlies, deep-layer shear sufficient for organized
   storms suggests potential that a few storms become severe, with
   locally damaging wind and/or hail possible, through the evening
   hours.

   ...Northern New York/New England...
   Models depict that a compact upper disturbance moving through the
   enhanced west-northwesterly mid-level flow field will cross northern
   New York/New England during the afternoon and evening.  A weak
   warm-frontal surface boundary possibly setting up across the area
   could serve as a focus for storm development, as the airmass
   diurnally destabilizes.  Given the enhanced, deep-layer
   west-northwesterlies aloft, a few fast-moving storms/storm clusters
   may evolve, with some risk for locally gusty/damaging winds.  Risk
   may persist into the evening, before the airmass stabilizes
   sufficiently.

   ...Central Appalachians/Mid Atlantic region...
   Models hint that as the prior eastern U.S. trough further decays,
   remnant short-wave energy may rotate anticyclonically across the
   central Appalachians/Mid Atlantic region during the afternoon and
   evening, possibly accompanied by slightly enhanced flow aloft.  This
   could support a couple of multicell clusters -- perhaps capable of
   isolated/minor tree damage.  While risk remains too low to outlook
   at this time, a MRGL area may be needed in later forecasts.

   ..Goss.. 08/21/2020

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