MESOSCALE DISCUSSION 1308
   NWS STORM PREDICTION CENTER NORMAN OK
   1152 AM CDT THU JUN 28 2007
   
   AREAS AFFECTED...A LARGE PORTION OF NEW ENGLAND...AND MUCH OF THE
   NRN MID ATLANTIC STATES/UPPER OH VALLEY
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 281652Z - 281815Z
   
   TRENDS ARE BEING MONITORED FOR THE POSSIBILITY OF AN INCREASING OR
   MORE FOCUSED SEVERE THREAT.  ONE OR MORE WATCHES ARE POSSIBLE THIS
   AFTERNOON.
   
   WITH INHIBITION WEAK IN PRE-FRONTAL ENVIRONMENT...INSOLATION IS
   ALREADY CONTRIBUTING TO THE DEVELOPMENT OF WIDELY SCATTERED
   THUNDERSTORMS FROM PARTS OF THE UPPER OHIO VALLEY THROUGH MUCH OF
   THE NORTHEASTERN STATES.  PRE-FRONTAL WIND SHIFT/LOW-LEVEL DRYING IS
   DIMINISHING CONVECTIVE POTENTIAL THROUGH MUCH OF UPSTATE NEW YORK
   THROUGH THE HUDSON/CHAMPLAIN VALLEY.  BUT...TO THE
   SOUTH/EAST...STORM COVERAGE IS EXPECTED TO STEADILY INCREASE IN
   COVERAGE THROUGH THE REMAINDER OF THE AFTERNOON.
   
   THIS WILL OCCUR MOSTLY TO THE SOUTH OF STRONGER MEAN CYCLONIC FLOW
   FIELD IN THE BASE OF EASTERN CANADIAN UPPER TROUGH.  AND...WEAK
   VERTICAL SHEAR WILL LIMIT OR SLOW CONVECTIVE ORGANIZATION. 
   HOWEVER...THERMODYNAMIC PROFILES WITH MIXED LAYER CAPE OF 1000-2000
   J/KG...AND UNSATURATED LOW/MID-LEVEL ENVIRONMENT...WILL BE
   SUPPORTIVE OF VIGOROUS UPDRAFTS AND DOWNDRAFTS...CAPABLE OF
   PRODUCING LOCALLY HEAVY RAINFALL...MARGINALLY SEVERE HAIL...AND
   STRONG GUSTY WINDS.
   
   AS COLD POOLS MERGE DURING THE PEAK AFTERNOON HEATING...
   CONSOLIDATING CONVECTION COULD SUPPORT A MORE ORGANIZED DAMAGING
   WIND THREAT.  THIS SEEMS MOST PROBABLE LATER THIS AFTERNOON/EVENING
   TO THE LEE OF THE NORTH CENTRAL APPALACHIANS ...FROM THE WASHINGTON
   D.C./BALTIMORE AREA INTO SOUTHERN NEW JERSEY...WHERE STRONGEST
   HEATING IS ONGOING ON THE SOUTHERN FRINGE OF THE WESTERLIES.

|posted by Sam Lillo @ 6/28/2007 01:02:00 PM