MESOSCALE DISCUSSION 1223
   NWS STORM PREDICTION CENTER NORMAN OK
   0352 PM CDT TUE JUN 25 2013

   AREAS AFFECTED...MAINE...NH...VT.

   CONCERNING...SEVERE THUNDERSTORM WATCH 361...

   VALID 252052Z - 252215Z

   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 361
   CONTINUES.

   SUMMARY...CONTINUE WW.  TSTM COVERAGE IS INCREASING ACROSS WW
   AREA...MOVING GENERALLY EWD INTO FAVORABLY UNSTABLE/UNCAPPED AIR
   MASS WITH POTENTIAL FOR DAMAGING GUSTS AND OCNL SVR HAIL.

   DISCUSSION...VIS SATELLITE AND RADAR REFLECTIVITY IMAGERY CONTINUES
   TO INDICATE LOW-AMPLITUDE SHORTWAVE PERTURBATION -- PROBABLY
   INCLUDING MCV GENERATED OVER UPPER GREAT LAKES REGION YESTERDAY --
   AND NOW MOVING EWD ACROSS SERN ONT AND PORTIONS NRN/ERN NY.  THIS
   FEATURE IS SERVING TWO PURPOSES BENEFITING CONVECTIVE
   ORGANIZATION/MAINTENANCE OVER REGION...
   1. SUBTLE LARGE-SCALE ASCENT/DESTABILIZATION ALOFT VIA DCVA AND
   2. ENHANCEMENT OF DEEP SHEAR...ESPECIALLY ACROSS WRN/NRN PORTION OF
   WW AND DISCUSSION AREA NEAR CANADA.

   ANTECEDENT/ONGOING SFC DIABATIC HEATING OF AIR MASS CONTAINING
   MID-60S TO LOW-70S F SFC DEW POINTS YIELDS MLCAPE 2000-3000
   J/KG...EXCEPT FOR LESSER BUT STILL CONVECTIVELY SUPPORTIVE VALUES 
   IN HIGHER ELEVATIONS OF VT/NH.  BUOYANCY PROBABLY IS NEAR PEAK
   ATTM...BUT SHOULD CONTINUE TO FAVOR CONVECTIVE MAINTENANCE EWD
   ACROSS WW AREA BEFORE OUTFLOW COVERAGE BECOMES SUBSTANTIAL IN
   ANOTHER 3-4 HOURS.  UPSTREAM ACTIVITY OVER ERN NY AND OVER ST
   LAWRENCE RIVER REGION OF QUE MAY AFFECT AREAS NEAR SRN AND NRN
   FRINGES OF WW AS WELL...ACROSS SRN NH/VT AND NRN MAINE RESPECTIVELY.
    COOL MARINE LAYER WILL LIMIT SERN EXTENT OF WIND THREAT...WHICH
   SHOULD EXTEND TO NEAR MAIN COAST GIVEN STG WLY COMPONENT TO
   PRECONVECTIVE SFC WINDS.

   ..EDWARDS.. 06/25/2013


   ATTN...WFO...CAR...GYX...BOX...BTV...ALY...

   LAT...LON   47306940 47066782 45736784 45606742 45396741 45316752
               45236722 44766700 44466773 44156834 43836960 43437035
               42867087 42917318 44977330 45047152 45307124 45317081
               45997019 47306940