MESOSCALE DISCUSSION 1757
   NWS STORM PREDICTION CENTER NORMAN OK
   0710 PM CDT TUE JUL 26 2011
   
   AREAS AFFECTED...SERN NY...CT...RI...MA...NH...WRN ME
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 687...
   
   VALID 270010Z - 270115Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 687
   CONTINUES.
   
   THE SVR THREAT ACROSS WW687 WILL BE CONFINED TO TWO SEPARATE
   AREAS...(1) WRN MAINE AND (2) SERN NY / SRN CT:
   
   1. WRN MAINE: GRAY ME WSR-88D DATA DEPICT AN ORGANIZED QLCS...WITH
   EMBEDDED LEWP AND BOWING STRUCTURES...MOVING EWD AROUND 30 KT. ON
   ITS PRESENT TRACK...IT COULD MOVE SLIGHTLY EAST OF WW687 DURING THE
   NEXT HOUR OR TWO. THIS ACTIVITY IS BEING SUSTAINED BY STRONG FORCING
   OVER THE SRN PERIPHERY OF A MID-LEVEL VORT MAX CENTERED OVER QUEBEC
   DESPITE VERY MEAGER INSTABILITY. THIS FORCING...COMBINED WITH 0-6-KM
   BULK SHEAR MAGNITUDES AROUND 40 KT /PER GRAY VWP DATA/...COULD HELP
   MAINTAIN CONVECTION IN THE NEAR TERM. HOWEVER...IT WILL LIKELY CROSS
   A N/S-ORIENTED SFC FRONT SHORTLY. EAST OF THIS FEATURE...MLCAPE
   BECOMES VERY MINIMAL OWING TO THE INLAND ADVECTION OF THE STABLE
   MARINE LAYER EAST OF THE BOUNDARY. HOWEVER...THE DEVELOPMENT OF A
   COLD POOL IN THE WAKE OF THE QLCS...MARKED BY SFC PRESSURE RISES OF
   2-3 MB WITHIN 2 HOURS OVER PORTIONS OF NRN VT/NH...COULD SUPPORT
   SOME CONVECTIVE SUSTENANCE AND A MARGINAL SVR WIND THREAT
   IMMEDIATELY TO THE EAST OF WW687 IN MAINE. HOWEVER...THE BRIEF
   SPATIOTEMPORAL NATURE OF THIS THREAT WILL PRECLUDE THE NEED FOR ANY
   ADDITIONAL WW OR WW EXTENSION.
   
   2. SERN NY / SRN CT...SCATTERED MULTICELLULAR CONVECTION OVER THE
   SRN FRINGES OF THE AFOREMENTIONED REGION OF ASCENT WILL CONTINUE
   DURING THE NEXT HOUR OR TWO...AS MODERATE DEEP-LAYER SHEAR REMAINS
   OVER THE REGION. RELATIVELY STEEPER LOW-LEVEL LAPSE RATES IN THIS
   REGION OWING TO PRECONVECTIVE TEMPERATURES IN THE MIDDLE/UPPER 80S
   WILL SUPPORT A THREAT FOR GUSTY WINDS...WITH ISOLATED INSTANCES OF
   DMGG WIND GUSTS POSSIBLE. THIS ACTIVITY COULD APPROACH THE NEW YORK
   CITY METRO AREA BY 01Z...THOUGH STABILIZATION OWING TO NOCTURNAL
   COOLING WILL LIKELY COMMENCE THEREAFTER AND MITIGATE THE SVR THREAT.
   
   ELSEWHERE ACROSS WW687...THE LACK OF STRONGER FORCING OR GREATER
   INSTABILITY WILL LIKELY MINIMIZE THE SVR THREAT. BASED ON CURRENT
   TRENDS...VALID PORTIONS OF WW687 WILL LIKELY BE ALLOWED TO EXPIRE ON
   TIME AT 02Z.
   
   ..COHEN.. 07/27/2011
   
   
   ATTN...WFO...CAR...GYX...BOX...BTV...OKX...ALY...
   
   LAT...LON   43706972 41537105 40887276 41097446 41827352 44577157
               45637061 45536888 43706972