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Mesoscale Discussion 1589
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   Mesoscale Discussion 1589
   NWS Storm Prediction Center Norman OK
   1202 PM CDT Mon Jul 25 2022

   Areas affected...Virginia into southeast Pennsylvania and southern
   New Jersey

   Concerning...Severe potential...Watch likely 

   Valid 251702Z - 251900Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Thunderstorms will continue to increase in coverage from
   central Virginia into southeast Pennsylvania and southern New Jersey
   through the afternoon as a cold front approaches the Mid-Atlantic
   region. Thunderstorms will primarily pose a damaging wind threat,
   and will likely require a watch.

   DISCUSSION...Latest GOES visible imagery reveals several convective
   cells developing along the WV/VA/MD border ahead of an approaching
   cold front and along a weak lee trough axis. Increasing lightning
   counts and cloud top heights have been noted with some of the deeper
   convection over the past 20 minutes, indicative of gradual
   intensification. These storms are forecast to migrate east into
   central/northern VA during the 17-19 UTC period, and will likely
   undergo further organization/intensification as they encounter an
   air mass featuring seasonally rich low-level moisture (which is
   supporting upwards of 1500-2000 J/kg MLCAPE) and around 20-30 knots
   of effective bulk shear (as estimated from recent ACARs soundings
   from the Washington D.C. area and recent KLWX and KDIX VWP obs).
   Furthermore, temperatures rising into the low 90s will support
   steepening boundary-layer lapse rates, and winds near the top of the
   boundary layer are forecast to increase to 25-35 mph by mid/late
   afternoon, both of which should foster the potential for damaging
   thunderstorm winds. A watch will likely be needed in the next 30-90
   minutes as thunderstorm coverage and intensity slowly increase.

   ..Moore/Guyer.. 07/25/2022

   ...Please see for graphic product...


   LAT...LON   37837661 37237799 37377920 37757965 38367938 39077873
               39667761 40127593 40067499 39577446 38397556 37837661 

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