Mesoscale Discussion 0841
   NWS Storm Prediction Center Norman OK
   1249 PM CDT Fri May 20 2022

   Areas affected...central and eastern Pennsylvania...extreme northern
   Virginia...far northern Maryland...northern Delaware...New Jersey

   Concerning...Tornado Watch 251...

   Valid 201749Z - 201915Z

   The severe weather threat for Tornado Watch 251 continues.

   SUMMARY...The severe threat continues across Tornado Watch 251.
   Damaging gusts remain the main threat, though a couple of tornadoes
   and perhaps marginal hail are still possible. The relatively highest
   severe threat is confined to a corridor in east-central PA into NJ,
   where greater low-level moisture and instability are present.

   DISCUSSION...An MCV continues to rapidly track eastward across PA,
   with thunderstorms developing ahead of the MCV center, both in a
   squall line across central PA, and with discrete cells in eastern
   PA. Adequate insolation has allowed surface temperatures to warm
   into the lower 80s F across southeast PA into central NJ,
   contributing to 500 J/kg MLCAPE. Instability is expected to remain
   weak given limited moisture (low to mid 60s F surface dewpoints)
   overspread by modest low and mid-level lapse rates. Nonetheless,
   recent observed KCCX VAD profiler data, 17Z mesoanalysis, and 16Z
   RAP forecast soundings show strong low-level shear present across
   southeast Pennsylvania toward the Delaware River. As such, a
   relatively higher corridor of severe potential exists across
   southeast PA into NJ, where the stronger shear overlaps available
   buoyancy. Damaging gusts are the main threat, though a couple of
   tornadoes/instances of marginal hail cannot be ruled out this
   afternoon.

   ..Squitieri/Hart.. 05/20/2022

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

   ATTN...WFO...OKX...PHI...BGM...CTP...LWX...

   LAT...LON   39057844 40157783 41147672 41357575 41357489 41247454
               40957430 40487405 40077416 39667448 39227508 39007627
               39057844