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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 www.spc.noaa.gov for graphic product...

ATTN...WFO...PHI...AKQ...CTP...LWX...RNK...

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