MESOSCALE DISCUSSION 0106
   NWS STORM PREDICTION CENTER NORMAN OK
   0700 PM CST WED FEB 11 2009
   
   AREAS AFFECTED...PA...ERN WV...MD...VA
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 20...
   
   VALID 120100Z - 120200Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 20
   CONTINUES.
   
   A FINE CONVECTIVE LINE CURRENTLY LOCATED FROM NW OH SWD ALONG THE
   SPINE OF THE APPALACHIANS...IS EXPECTED TO CONTINUE ENEWD INTO THE
   MID-ATLANTIC THROUGH LATE EVENING. ALTHOUGH THE WIDESPREAD POTENTIAL
   FOR WIND DAMAGE SHOULD DECREASE...ENOUGH OF A WIND DAMAGE THREAT
   SHOULD CONTINUE FOR WW ISSUANCE UPSTREAM FROM WW 20.
   
   WATER VAPOR IMAGERY CONTINUES TO SHOW A WELL-DEVELOPED DRY SLOT
   EXTENDING SWD FROM CNTRL OH SWD INTO FAR WRN VA WITH RUC ANALYSIS
   SHOWING VERY STRONG LARGE-SCALE ASCENT ALONG THE LEADING EDGE OF THE
   DRY SLOT. THIS ALONG WITH STRONG VERTICAL SHEAR IS SUPPORTING A
   SQUALL-LINE LOCATED JUST TO THE EAST OF THE DRY SLOT. ALTHOUGH
   INSTABILITY REMAINS VERY WEAK AHEAD OF THE LINE...THE VERY FOCUSED
   ASCENT COMBINED WITH STRONG UPPER-LEVEL DIVERGENCE SHOULD ALLOW THE
   LINE TO BE MAINTAINED EAST OF THE APPALACHIAN MTNS INTO THE
   MID-ATLANTIC LATE THIS EVENING. FORECAST RUC SOUNDINGS ACROSS CNTRL
   AND NRN VA THIS EVENING SHOW MORE MOISTURE IN THE LOW TO MID-LEVELS
   THAN IN AREAS FURTHER NORTH SUGGESTING THE LINE HAS A BETTER CHANCE
   OF REMAINING STRONG OVER THE SRN HALF OF THE MD AREA.
   
   ..BROYLES.. 02/12/2009
   
   
   ATTN...WFO...PHI...BGM...AKQ...BUF...CTP...LWX...RNK...PBZ...
   RLX...CLE...
   
   LAT...LON   40887592 41807608 42227650 42447723 42517797 42447848
               42387905 41907991 41498042 40988057 39127993 37828052
               37118081 36727935 37477737 39517602 40887592