MESOSCALE DISCUSSION 1503
   NWS STORM PREDICTION CENTER NORMAN OK
   0600 PM CDT TUE JUL 21 2015

   AREAS AFFECTED...SERN PA...NRN AND CNTRL NJ...SERN NY AND CNTRL
   THROUGH ERN CT

   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

   VALID 212300Z - 220030Z

   PROBABILITY OF WATCH ISSUANCE...20 PERCENT

   SUMMARY...STORMS WILL POSE A THREAT FOR MARGINALLY SEVERE WIND GUSTS
   THROUGH AROUND 01Z FROM SERN PA THROUGH THE NY CITY AREA INTO CT.
   DURATION AND MAGNITUDE OF THREAT ARE LIMITED AND A WW IS NOT
   ANTICIPATED.

   DISCUSSION...A PRE-FRONTAL SQUALL LINE EXTENDS FROM SERN PA TO NEAR
   THE NY CITY AREA INTO WRN CT AND IS MOVING SE AT AROUND 35 KT.
   LATEST OBJECTIVE ANALYSIS SHOWS THE ATMOSPHERE REMAINS MODERATELY
   UNSTABLE WITH 1000 TO 1500 J/KG MLCAPE AND WEAK MID-LEVEL LAPSE
   RATES. THE STORMS ARE EMBEDDED WITHIN MODEST /15-20 KT/ WLY FLOW
   WITHIN THE LOWEST 4 KM. WINDS INCREASE TO AROUND 40 KT AT 5 KM. THIS
   ENVIRONMENT SUPPORTS PRIMARILY MULTICELL MODES WITH SOME MARGINAL
   SUPERCELL STRUCTURES ALSO POSSIBLE. DPVA AND MODEST CONVERGENCE
   ALONG LEADING GUST FRONT WILL HELP SUSTAIN ACTIVITY NEXT COUPLE OF
   HOURS...BUT A GRADUAL DECREASE IS EXPECTED WITH ONSET OF NOCTURNAL
   COOLING.

   ..DIAL/MEAD.. 07/21/2015


   ATTN...WFO...BOX...OKX...PHI...

   LAT...LON   40017554 40897379 41637261 41447190 40567313 39787512
               40017554