Areas affected...eastern Ohio...much of Pennsylvania and into parts
   of New Jersey...Maryland...northern and eastern West Virginia...and
   northern Virginia

   Concerning...Severe potential...Watch unlikely 

   Valid 282151Z - 282345Z

   Probability of Watch Issuance...5 percent

   SUMMARY...Local risk for gusty/damaging winds and marginal hail is
   evident early this evening across portions of the central
   Appalachians/mid Atlantic region.  Threat will likely remain
   isolated and temporally limited however, likely precluding the need
   for a WW.

   DISCUSSION...Latest surface analysis shows a cold front arcing from
   eastern New York into central Pennsylvania, and then westward into
   central portions of Ohio and Indiana.  Near and ahead of this
   boundary, diurnal heating has pushed surface temperatures well into
   the 80s.  This, in conjunction with a moist warm sector (dewpoints
   into the mid 60s) is resulting in 1000 to 1500 J/kg mixed-layer CAPE
   across the discussion area.

   Storms have formed in two distinct areas -- across parts of eastern
   Ohio near the front, and into central Pennsylvania over the higher
   ridges of the Appalachian front.  This is loosely in line with some
   CAM guidance -- particularly the HRRR that suggests both of these
   areas of development should continue to blossom over the next couple
   of hours, possibly evolving into loosely organized clusters.  

   Area VWP data confirms model forecasts of a strengthening westerly
   flow field with height, and the resulting speed shear may enhance
   the potential for storm organization.  As such, locally
   gusty/damaging winds may occur with stronger updrafts, and marginal
   hail also appears possible (particularly with the eastern Ohio
   storms where some updraft rotation has been indicated by radar in
   the past half hour).

   Given the overall isolated nature of the convection that is
   expected, and the sub-optimal time of day, risk should remain
   limited in both duration and intensity.  As such, WW issuance is not
   anticipated.

STEVEN'S THOUGHTS:

A few of these thunderstorms will be capable of producing heavy downpours and wind gusts over 50 mph through 9 PM this evening.  Most of the showers will collapse before reaching the coast.  However, the Delawere River Valley has the best chance for thunderstorms.
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