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Mesoscale Discussion 1215
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   Mesoscale Discussion 1215
   NWS Storm Prediction Center Norman OK
   0335 PM CDT Fri Jul 09 2021

   Areas affected...portions of southeast New York into eastern
   Pennsylvania...far northeast Maryland...western New Jersey

   Concerning...Severe potential...Watch possible 

   Valid 092035Z - 092230Z

   Probability of Watch Issuance...40 percent

   SUMMARY...The severe threat continues to increase across portions of
   the Mid Atlantic this afternoon. Damaging gusts remain the primary
   threat with the stronger, longer-lived storms. Conditions will
   continue to be monitored for the need of a Severe Thunderstorm Watch
   issuance.

   DISCUSSION...Multicellular clusters, evident via MRMS mosaic radar
   imagery, have demonstrated small, bow-type structures over the past
   hour or so, with some damaging gusts reported. These storms are
   progressing in an environment characterized by widespread, poor
   mid-level lapse rates, but with 7+ C/km 0-3km lapse rates (evident
   via 20Z mesoanalysis and 19Z RAP forecast soundings). The
   aforementioned low-level lapse rates atop upper 60s to 70 F surface
   dewpoints are contributing to 1000-1500 J/kg MLCAPE amid 40+ kt
   effective bulk shear. These bulk shear vectors are oriented roughly
   perpendicular to the smaller linear segments. As such, storms are
   expected to continue supporting damaging gust potential through the
   remainder of the diurnal heating cycle. It is unclear how widespread
   the damaging gust threat will be through the remainder of the
   afternoon. Conditions will continue to be monitored for the need of
   a Severe Thunderstorm Watch issuance should it become evident that
   more widespread damaging gusts will become likely.

   ..Squitieri/Bunting.. 07/09/2021

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

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

   LAT...LON   39667526 39547579 39607655 40087747 40257770 41647647
               42497520 42377471 41867430 41277423 40427469 39737526
               39667526 

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