MESOSCALE DISCUSSION 1604
   NWS STORM PREDICTION CENTER NORMAN OK
   0459 AM CDT TUE AUG 04 2015

   AREAS AFFECTED...EASTERN LONG ISLAND...EASTERN CT...RI...AND
   SOUTHEAST MA

   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

   VALID 040959Z - 041230Z

   PROBABILITY OF WATCH ISSUANCE...5 PERCENT

   SUMMARY...A FAST-MOVING STORM /TOWARD THE ENE AROUND 45-50
   KT/...CURRENTLY AFFECTING AREAS ACROSS AND OFFSHORE OF NORTHEAST
   LONG ISLAND...WILL TRACK ACROSS BLOCK ISLAND AND THE SOUTHERN PART
   OF RI BY 1030Z.  THIS STORM ALONG WITH ADDITIONAL STORMS DEVELOPING
   IN SOUTHERN NEW ENGLAND ARE EXPECTED TO MOVE TO THE ENE ACROSS THE
   REST OF RI AND SOUTHEAST MA INCLUDING MARTHAS VINEYARD AND NANTUCKET
   BETWEEN 1030-12Z.  ISOLATED STRONG WIND GUSTS APPROACHING OR LOCALLY
   EXCEEDING 50 KT AND HAIL...POTENTIALLY NEAR 1 INCH IN
   DIAMETER...WILL BE THE PRIMARY SEVERE THREATS.

   DISCUSSION...AT 0950Z...MOSAIC RADAR IMAGERY SHOWED A FAST-MOVING
   STRONG TO SEVERE STORM EXTENDING FROM EXTREME NORTHEAST LONG ISLAND
   NORTH TO THE COAST OF CT...WITH ADDITIONAL STORMS DEVELOPING ACROSS
   SOUTHERN NEW ENGLAND.  THE DOWNSTREAM BOUNDARY LAYER ACROSS RI AND
   SOUTHEAST MA HAS HIGHER SURFACE DEW POINTS AS COMPARED TO AREAS
   FARTHER TO THE W/SW IN NJ/ERN PA/MD...RESULTING IN GREATER
   INSTABILITY AND A HIGHER POTENTIAL FOR STORMS TO BECOME
   SURFACE-BASED EARLY THIS MORNING.  FORCING FOR ASCENT/DPVA WILL
   ADVANCE ENEWD ACROSS SOUTHERN NEW ENGLAND AND VICINITY THROUGH THE
   EARLY MORNING...WHILE 50+ KT SWLY 500-MB WINDS ENHANCES DEEP SHEAR
   WITHIN A MODERATELY UNSTABLE ENVIRONMENT TO SUPPORT A FEW STRONGER
   AND ORGANIZED STORMS.  GIVEN THE FORWARD SPEED OF THE PRIMARY
   NORTHEAST LONG ISLAND STORM AND THE GREATER POTENTIAL FOR STORMS TO
   BECOME SURFACE-BASED...THE GREATEST SEVERE-WEATHER THREAT WILL BE
   LOCALLY STRONG WIND GUSTS...WHILE HAIL IS AN ISOLATED...SECONDARY
   THREAT.

   ..PETERS/EDWARDS.. 08/04/2015


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

   LAT...LON   41627234 41807169 41877076 41817013 41666990 41246993
               41107065 41007133 40837209 40747277 41627234