MESOSCALE DISCUSSION 2073
   NWS STORM PREDICTION CENTER NORMAN OK
   0301 AM CDT SUN AUG 28 2011
   
   AREAS AFFECTED...PORTIONS NJ...EXTREME ERN PA...SERN NY INCLUDING
   LONG ISLAND...SRN COASTAL NEW ENGLAND.
   
   CONCERNING...TORNADO WATCH 812...
   
   VALID 280801Z - 280930Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 812 CONTINUES.
   
   WW MAY BE REPLACED BEFORE SCHEDULED 09Z EXPIRATION...POSSIBLY
   INCLUDING SOME COASTAL NEW ENGLAND COUNTIES AND TAKING OUT BULK OF
   NJ.
   
   FARTHER S ACROSS MID-ATLANTIC...PRIND TORNADO THREAT WILL END FROM
   SSW-NNE IN STEP WITH AND AHEAD OF CORE REGION OF HURRICANE
   IRENE...WHICH IS CONVECTIVELY-DEPRIVED IN MOST FAVORABLE
   THERMODYNAMIC AIR MASS OVER ATLANTIC WATERS.  ANY REMAINING TORNADO
   THREAT WILL BE WITH MIDDLE-OUTER BANDS WHOSE CELLS MOVE NWWD FROM
   OPTIMALLY FAVORABLE AIR MASS TO COAST.  SUCH CELLS MAY RETAIN SOME
   STORM-SCALE ROTATION BEFORE MOVING INTO MORE STABLE AND PRECIP-LADEN
   AIR MASS INLAND.  THOUGH DEFINITELY NON-ZERO...TORNADO POTENTIAL MAY
   UNDERGO RELATIVE NOCTURNAL MIN OVER NEXT SEVERAL HOURS.  LOW-LEVEL
   SHEAR WILL REMAIN FAVORABLE OVER VAST AREA N THROUGH NE OF
   CENTER...WITH 0-1 KM AGL SRH 400-600 J/KG FOR NWWD-MOVING CELLS IN
   BANDS.  REMAINING THREAT THEREFORE WILL BE REGULATED BY AVAILABLE
   INSTABILITY.
   
   PRIND FAVORABLE BUOYANCY WILL STAY VERY NEAR COAST...WITH CONTINUED
   RAIN-COOLING OF INLAND AIR MASS ON BOTH SIDES OF QUASISTATIONARY SFC
   FRONTAL ZONE.  AT 07Z...FRONT WAS ANALYZED FROM NERN MA WSWWD ACROSS
   NWRN CT TO N-CENTRAL NJ AND EXTREME ERN PA...BEFORE BECOMING
   DIFFUSED/ENTANGLED WITH CIRCULATION OF IRENE.  RAOBS AND MODEL
   SOUNDINGS...MODIFIED BOTH FOR SFC CONDITIONS AND FOR WARMING ALOFT
   WITH PROXIMITY TO CORE OF IRENE...SUGGEST MLCAPE BECOMING NEGLIGIBLE
   OR DISAPPEARING WITH DEVELOPING SFC TEMPS LESS THAN ABOUT 75
   F...THAT ISOTHERM REMAINING ALONG OR SE OF SFC FRONT.
   
   REF LATEST NHC ADVISORIES FOR TRACK/INTENSITY GUIDANCE ON IRENE.
   
   ..EDWARDS.. 08/28/2011
   
   
   ATTN...WFO...BOX...OKX...PHI...
   
   LAT...LON   40137409 40237508 41347384 41617250 41597144 41357046
               41307083 41447104 41387152 41177154 40997200 40627322
               40537395 40137409