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Mesoscale Discussion 1310
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MD 1310 graphic

   Mesoscale Discussion 1310
   NWS Storm Prediction Center Norman OK
   1209 PM CDT Fri Jul 14 2017

   Areas affected...Eastern West Virginia...northern Virginia...much of
   Maryland...Delaware...southern Pennsylvania...and southwestern New

   Concerning...Severe potential...Watch possible 

   Valid 141709Z - 141915Z

   Probability of Watch Issuance...60 percent

   SUMMARY...Convective trends are being monitored for a possible
   severe thunderstorm watch that may be needed after 18Z or so.

   DISCUSSION...A couple of thunderstorm clusters (one over central
   Pennsylvania and another newly developing over northern West
   Virginia) were gradually increasing in intensity recently.  This
   increase in coverage/intensity is likely tied to strong surface
   heating amidst a weakly capped airmass, with MUCAPE values
   approaching 3000 J/kg in some areas.  The region resides on the
   southern flank of enhanced mid-level flow (40-45 knots over
   Pennsylvania), which will likely support at least loosely organized
   and forward-propagating convection over the course of the afternoon,
   with a primary risk of damaging wind gusts near the strongest
   activity especially from northern Virginia eastward to the DelMarVa
   Peninsula later in the afternoon.

   Farther north into southern Pennsylvania/New Jersey, a nearly
   stationary frontal zone was located from near Harrisburg, PA
   east-southeastward to near Atlantic City, NJ.  Along this zone,
   backed surface winds and low-to-mid 70s F dewpoints may contribute
   to updraft rotation, especially with any storms that can develop on
   the southern flank of ongoing activity in central Pennsylvania.  The
   orientation of this boundary favors a relatively long residence time
   for updrafts that can root near the surface and move/propagate just
   to the right of the mean flow vector, and an isolated tornado cannot
   be completely ruled out given this regime.

   Convective trends are being monitored, and a severe thunderstorm
   watch may be needed later this afternoon especially if convective
   trends continue as currently observed.

   ..Cook/Hart.. 07/14/2017

   ...Please see for graphic product...


   LAT...LON   38417969 38947989 39407968 39927869 40437733 40537656
               40387540 40027460 39767450 39297471 38547524 38057593
               37877693 37997852 38417969 

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