MESOSCALE DISCUSSION 1699
   NWS STORM PREDICTION CENTER NORMAN OK
   0713 PM CDT FRI JUL 22 2011
   
   AREAS AFFECTED...ERN OH...WRN/CNTRL PA...FAR WRN MD...NRN WV
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 672...
   
   VALID 230013Z - 230115Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 672
   CONTINUES.
   
   LATEST MESOANALYSIS DEPICTS THE LEADING EDGE OF A CONVECTIVELY
   INDUCED COLD POOL ARCING FROM PORTIONS OF CNTRL PA INTO PORTIONS OF
   NRN WV AND ERN OH. DESPITE CONVERGENCE ALONG THIS FEATURE...GPS DATA
   DEPICT AN AXIS OF LIMITED PWAT VALUES -- AOB 1.25 INCHES -- AHEAD OF
   THIS FEATURE ACROSS CNTRL PA...SUGGESTIVE OF DRIER AIR ALOFT.
   PRECONVECTIVE VERTICAL MIXING OF THIS DRIER AIR INTO THE BOUNDARY
   LAYER IS SUPPORTING SFC DEWPOINTS IN THE UPPER 40S AND THE
   50S...LIMITING THE DEGREE OF POTENTIAL BUOYANCY OVER CNTRL PA. IN
   THIS AREA...THE THREAT FOR SVR STORMS MAY BE LIMITED. FARTHER
   SOUTH...RICHER DEEP-LAYER MOISTURE WITH SFC DEWPOINTS IN THE MIDDLE
   60S TO LOWER 70S WILL FOSTER DEEP CONVECTION INVOF THE SRN FLANK OF
   THE COLD POOL. THIS WILL CONFINE THE PRIMARY SVR THREAT TO AREAS
   SOUTH OF INTERSTATE 70...WHERE DMGG WIND GUSTS WILL BE THE PRIMARY
   CONCERN WITH MULTICELLULAR CLUSTERS. HOWEVER...THE LACK OF STRONGER
   VERTICAL SHEAR IN THIS REGION PER AREA VWP DATA COULD ALLOW OUTFLOW
   TO OUTRUN PARENT CONVECTION...POTENTIALLY LIMITING THE SUSTENANCE OF
   CONVECTION.
   
   ..COHEN.. 07/23/2011
   
   
   ATTN...WFO...CTP...LWX...PBZ...RLX...CLE...
   
   LAT...LON   40297803 39717887 39277968 39658144 40568140 41188065
               41527962 41397803 40297803