SPC AC 291734

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1234 PM CDT Wed Jul 29 2020

   Valid 301200Z - 311200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
   SOUTHERN PLAINS TO THE SOUTHERN APPALACHIANS AND FROM THE
   MID-ATLANTIC INTO SOUTHERN NEW ENGLAND...

   ...SUMMARY...
   Strong thunderstorms may impact parts of the south central Great
   Plains, the Tennessee Valley into the southern Appalachians, and
   southern New England into the Mid Atlantic Thursday into Thursday
   night, accompanied by at least some risk for severe weather.

   ...Synopsis...
   The overall synoptic pattern will be characterized by broad
   mid-level troughing across much of the eastern two-thirds of the
   CONUS and an amplifying ridge over the Desert Southwest.  A belt of
   enhanced mid-level flow will accompany the trough across the
   southern Plains, Tennessee Valley, Appalachians, and
   Mid-Atlantic/Northeast.  Southwesterly flow aloft will also be
   enhanced across the Pacific Northwest by an upstream longwave trough
   over the northeastern Pacific.  

   At the surface, a weak front will migrate southward across the
   southern Plains and mid-Mississippi Valley area through the day. 
   This front will extend eastward across the central Appalachians,
   mid-Atlantic, and southern New England and may be augmented by the
   presence of convection in the early morning hours especially across
   Arkansas and western Tennessee.  South of the front/outflow,
   insolation amidst a moist airmass characterized by 60s to 70s F
   dewpoints will foster moderate to strong buoyancy, with steeper
   lapse rates especially from west Texas into Oklahoma.  Scattered
   clusters of storms are expected to develop/strengthen in the
   afternoon and pose a hail/wind risk.

   ...Southern Plains to southern Appalachians...
   One or two linear complexes may be ongoing at the beginning of the
   period across portions of Arkansas and Tennessee.  Throughout the
   day, heating ahead of any convective complexes and lift/ascent
   associated with attendant surface boundaries and mid-level shortwave
   trough(s) will encourage renewed convective development through the
   afternoon and evening.  Westerly flow aloft will aid in upscale
   growth into forward-propagating clusters and linear segments, which
   should encourage a damaging-wind risk.  Hail may also occur across
   portions of west Texas and Oklahoma where steeper low- and mid-level
   lapse rates reside.  Much of the severe risk will be diurnally
   driven, though at least a limited severe risk may exist downstream
   of any organized complexes that can sustain themselves after dark.

   ...Mid-Atlantic into southern New England...
   Storms will gradually develop and intensify along and ahead of a
   weak surface front entering the region in the afternoon.  The
   airmass ahead of the front will be moderately unstable and weakly
   capped, with 40-45 knots of deep shear supportive of modest storm
   organization despite relatively weak surface flow.  A few linear
   segments/clusters of storms will produce wind/tree damage in the
   afternoon and early evening, with the greatest coverage of storms
   expected across Virginia/southern Maryland late in the day.

   ..Cook.. 07/29/2020

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