Mesoscale Discussion 1263
NWS Storm Prediction Center Norman OK
0758 PM CDT Sun Jul 11 2021
Areas affected...Eastern Pennsylvania...far northern Maryland
Concerning...Severe Thunderstorm Watch 372...
Valid 120058Z - 120200Z
The severe weather threat for Severe Thunderstorm Watch 372
SUMMARY...A threat for damaging winds will continue for another 1-2
hours. With time, though, the threat is expected to become more
marginal and isolated. No downstream watch is planned this evening.
DISCUSSION...A line of thunderstorms producing occasional wind
damage in central Pennsylvania will continue eastward this evening.
As temperatures cool ahead of the line and the influence of the MCV
to the north lessens, storms are likely to undergo a weakening trend
over the next couple of hours. In the short term, a small bookend
vortex near Columbia County, PA, will pose the greatest wind gusts
threat. This feature is near instability gradient and will be moving
into cooler, more stable air within the next 1-2 hours. A remaining
pocket of 1000-2000 J/kg MLCAPE in east-central Pennsylvania into
far northern Maryland may promote a few damaging gusts through 10-11
PM EDT. The southward extent of the threat is most is question as
low/mid-level forcing is weaker. Given the small spatial and
temporal extent of an increasingly marginal severe threat, no
downstream watch is planned this evening.
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