MESOSCALE DISCUSSION 1427
   NWS STORM PREDICTION CENTER NORMAN OK
   0956 AM CDT MON JUL 09 2007
   
   AREAS AFFECTED...NERN NY/VT/NH
   
   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 
   
   VALID 091456Z - 091600Z
   
   SEVERE THREAT IS EXPECTED TO INCREASE THROUGH THE MORNING.  A WW
   WILL LIKELY BE REQUIRED.
   
   TSTMS HAVE RECENTLY INTENSIFIED OVER FRANKLIN AND ESSEX COUNTIES IN 
   NERN NY...IMMEDIATELY TO THE E OF SURFACE WARM FRONT SHIFTING EWD
   THROUGH THE HUDSON VALLEY.  WATER VAPOR IMAGERY AND BURLINGTON VT
   VWP SUGGEST THAT THIS ACTIVITY IS LIKELY BEING DRIVEN BY AN ENHANCED
   ZONE OF LOW-LEVEL WAA ALONG THE SRN FRINGE OF A MID-LEVEL SHORT WAVE
   TROUGH/SPEED MAXIMUM TRANSLATING EWD ACROSS SWRN QB.  
   
   VERTICAL SHEAR INVOF WARM FRONT IS QUITE STRONG AS OBSERVED BY THE
   BURLINGTON VWP...HOWEVER THE PRIMARY UNCERTAINTY ATTM IS THE DEGREE
   OF INSTABILITY...ESPECIALLY AS STORMS CONTINUE EWD INTO A
   PROGRESSIVELY COOLER LOW-LEVEL AIR MASS E OF WARM FRONT.  RUC
   PROXIMITY SOUNDINGS SUGGEST THAT LOCAL ENVIRONMENT IS CURRENTLY
   MARGINALLY UNSTABLE WITH MUCAPES OF 300-400 J/KG.  SOME BREAKS IN
   THE CLOUDS HAVE BEEN NOTED ON VISIBLE SATELLITE OVER WRN VT WHICH
   SHOULD SUPPORT LOCALLY STRONG DIABATIC HEATING AND FURTHER
   DESTABILIZATION.
   
   CURRENT THINKING IS THAT SEVERE THREAT SHOULD REMAIN ISOLATED FOR
   THE NEXT HOUR OR SO...OWING LARGELY TO THE LIMITED INSTABILITY. 
   THIS THREAT SHOULD INCREASE THROUGH THE LATE MORNING INTO EARLY
   AFTERNOON AS FURTHER AIR MASS DESTABILIZATION OCCURS INVOF WARM
   FRONT.  VERTICAL SHEAR PROFILES ARE SUPPORTIVE OF SUPERCELLS WITH
   THE MAIN THREATS BEING LARGE HAIL AND DAMAGING WINDS.  STORMS MAY
   TEND TO REMAIN SLIGHTLY ELEVATED ABOVE A SHALLOW NEAR SURFACE STABLE
   LAYER...EFFECTIVELY LIMITING A MORE SUBSTANTIAL TORNADO THREAT.
   
   ..MEAD.. 07/09/2007
   
   
   ATTN...WFO...GYX...BTV...ALY...
   
   44047456 44817493 45017441 45037322 45007218 44967125
   44277125 43217218 43247315 43317399