MESOSCALE DISCUSSION 1583
   NWS STORM PREDICTION CENTER NORMAN OK
   0355 PM CDT THU JUL 16 2009
   
   AREAS AFFECTED...PARTS OF THE DE RIVER VALLEY / UPSTATE NY / VT
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 587...
   
   VALID 162055Z - 162200Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 587
   CONTINUES.
   
   STRONG TO SEVERE TSTMS WILL CONTINUE TO AFFECT THE DISCUSSION AREA
   THROUGH THE LATE AFTERNOON INTO THE EARLY EVENING HOURS.  THE MAIN
   THREATS WITH THE STRONGER STORMS WILL CONTINUE TO BE ISOLD DMGG WIND
   GUSTS AND MARGINALLY SEVERE HAIL.
   
   RECENT RADAR MOSAIC SHOWS AN ARCING SCTD BAND OF STRONG/SEVERE
   STORMS EXTENDING FROM EXTREME NERN ONTARIO INTO THE CHAMPLAIN VALLEY
   SWD INTO NERN PA.  SURFACE DATA/VISIBLE SATELLITE IMAGERY SHOW A
   LAKE BREEZE ORIGINATING FROM LAKE ONTARIO HAS EFFECTIVELY STABILIZED
   THE AIRMASS OVER THE ADIRONDACKS /W OF ONGOING STORMS OVER THE
   CHAMPLAIN VALLEY/.  THESE STORMS WILL LIKELY CONTINUE TO MAINTAIN
   THEIR VIGOR FOR THE NEXT FEW HOURS BEFORE GRADUAL LOSS OF DAYTIME
   HEATING CONTRIBUTES TO A LESS UNSTABLE AIRMASS AND AN OVERALL
   WEAKENING TREND IN STORM INTENSITY.  BEFORE THIS OCCURS...STRONG
   DEEP LAYER SHEAR /35-50 KTS 0-6 KM/ IN AREA VWP DATA WILL SUPPORT
   STORM ORGANIZATION WITH OCCASIONAL STORM-SCALE ROTATION POSSIBLE.
   
   ..SMITH.. 07/16/2009
   
   
   ATTN...WFO...GYX...BOX...BTV...OKX...ALY...PHI...BGM...