MESOSCALE DISCUSSION 1698
   NWS STORM PREDICTION CENTER NORMAN OK
   0141 PM CDT THU AUG 09 2007
   
   AREAS AFFECTED...PARTS OF SRN PA...MD...NRN VA AND THE DELMARVA
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 573...574...
   
   VALID 091841Z - 092015Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
   573...574...CONTINUES.
   
   A NEW WW REPLACING WWS 573 AND 574 WILL LIKELY BE NEEDED BY 20Z.
   
   SIGNIFICANT SURFACE COLD POOL GENERATED BY SMALL MESOSCALE
   CONVECTIVE SYSTEM CONTINUES TO ADVANCE SOUTHEASTWARD AROUND 30
   KTS...AND WILL LIKELY SPREAD THROUGH COASTAL AREAS BY 20-21Z.  THE
   CONVECTIVE SYSTEM CONTINUES TO DECAY...AND THE COLD POOL WILL
   PROBABLY WEAKEN AS WELL.  BUT...OUTFLOW BOUNDARY TO THE SOUTH/WEST
   OF THE WASHINGTON D.C. AREA IS BECOMING A FOCUS FOR INCREASING
   STORMS OFF THE NORTHERN BLUE RIDGE.  AND...PERHAPS MORE
   SIGNIFICANTLY...A NEW CONVECTIVE CLUSTER CONTINUES TO EVOLVE ALONG
   FRONTAL ZONE UPSTREAM...ACROSS PARTS OF THE UPPER OHIO VALLEY...
   WHICH APPEARS LIKELY TO BEGIN TO SPREAD INTO SOUTH CENTRAL
   PENNSYLVANIA AND ADJACENT PORTIONS OF MARYLAND BY 21-22Z.  WITH
   FORWARD MOTION AIDED BY 30-35 KT WEST NORTHWESTERLY 500 MB FLOW
   ...DAMAGING WIND POTENTIAL WILL ACCOMPANY AN EXPANDING COLD POOL
   GENERATED BY THIS SYSTEM...MAINTAINING A SEVERE THREAT ACROSS PARTS
   OF THE MID ATLANTIC REGION THROUGH EARLY EVENING.
   
   ..KERR.. 08/09/2007
   
   
   ATTN...WFO...PHI...AKQ...CTP...LWX...PBZ...
   
   40667999 40807913 40407823 39637716 39057648 38517559
   37817560 37637637 38007727 38457788 39477990