MESOSCALE DISCUSSION 1694
   NWS STORM PREDICTION CENTER NORMAN OK
   0747 AM CDT THU AUG 09 2007
   
   AREAS AFFECTED...S-CNTRL/SERN PA INTO THE DELMARVA
   
   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 
   
   VALID 091247Z - 091345Z
   
   THE POTENTIAL FOR DAMAGING WINDS WITH EVOLVING MCS IS EXPECTED TO
   INCREASE THROUGH THE MORNING.  CONVECTIVE TRENDS ARE BEING MONITORED
   FOR A WW.
   
   RECENT TRENDS IN REGIONAL RADAR IMAGERY INDICATE THAT CLUSTER OF
   TSTMS OVER WRN PA /ARMSTRONG...INDIANA AND WESTMORELAND COUNTIES AS
   OF 1235Z/ WHERE BECOMING INCREASINGLY ORGANIZED.  LATEST
   MESOANALYSIS SHOWS THAT THIS TSTM COMPLEX IS SITUATED ALONG A
   LOW-LEVEL BAROCLINIC ZONE EXTENDING FROM THE SRN GREAT LAKES SEWD
   THROUGH S-CNTRL PA INTO THE DELMARVA.  WHILE 12Z PIT SOUNDING
   INDICATED A VERY MOIST AND MARGINALLY UNSTABLE
   ENVIRONMENT...MODIFICATION OF DOWNSTREAM IAD SOUNDING FOR CURRENT
   SURFACE TEMPERATURES OF 80-85F YIELDS AN ALREADY MODERATELY UNSTABLE
   AIR MASS WITH MUCAPES OF 2000-2500 J/KG.
   
   CURRENT PIT VWP SHOWS A RELATIVELY FAVORABLE WIND PROFILE FOR
   DOWNSHEAR COLD POOL ELONGATION/FORWARD PROPAGATION WITH LARGELY
   UNIDIRECTIONAL WLY FLOW WITH 40 KT WINDS AS LOW AS 3 KM AGL.  GIVEN
   THIS TYPE OF KINEMATIC ENVIRONMENT AND MODERATELY UNSTABLE
   DOWNSTREAM AIR MASS...EXPECT ABOVE-MENTIONED TSTM CLUSTER TO FURTHER
   INTENSIFY AS IT CONTINUES SEWD ALONG IMMEDIATE COOL SIDE OF
   LOW-LEVEL BAROCLINIC ZONE.  DAMAGING WINDS WILL BE THE PRIMARY
   SEVERE WEATHER HAZARD WITH THIS SYSTEM.
   
   ..MEAD.. 08/09/2007
   
   
   ATTN...WFO...PHI...CTP...LWX...
   
   40347860 40557803 40227660 39487567 38897609 38947675
   39577826 39887881