MESOSCALE DISCUSSION 0096
   NWS STORM PREDICTION CENTER NORMAN OK
   0919 AM CST WED JAN 30 2013
   
   AREAS AFFECTED...WRN AND CNTRL PA...W VA...WRN AND CNTRL MD/VA
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 20...
   
   VALID 301519Z - 301645Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 20
   CONTINUES.
   
   SUMMARY...RISK FOR STRONG SURFACE GUSTS CONTINUES WITH A NARROW LINE
   OF ENHANCED SHOWERS ADVANCING ACROSS THE WW AREA.  ACTIVITY MAY
   BEGIN SPREADING EAST OF THE WW BY 17Z...BUT IT IS NOT CLEAR THAT A
   NEW WW WILL BE NEEDED.
   
   DISCUSSION...THE NARROW...ENHANCED...BUT STILL
   LOW-TOPPED...PRE-FRONTAL SQUALL LINE CONTINUES TO ADVANCE EASTWARD
   AROUND 35 KT...INTO AND THROUGH THE CENTRAL APPALACHIANS.  ALTHOUGH
   ACTIVITY IS NOT DEEP ENOUGH TO EXTEND THROUGH THE FAVORABLE MIXED
   PHASE LAYER FOR THE DEVELOPMENT OF CHARGE SEPARATION...AND
   LIGHTNING...SHOWERS HAVE BEEN ENHANCING THE DOWNWARD TRANSFER OF
   MOMENTUM ASSOCIATED WITH 50-60+ KT SOUTHERLY FLOW PRESENT JUST ABOVE
   THE SURFACE.  THIS MAY CONTINUE EASTWARD ACROSS THE CREST THE
   APPALACHIANS DURING THE NEXT COUPLE OF HOURS.  AS THE NORTHERN EDGE
   OF THIS ACTIVITY SPREADS EAST OF THE WATCH BY AROUND 17Z...A
   LINGERING RESIDUAL COOL AND STABLE BOUNDARY LAYER AIR MASS ACROSS
   CENTRAL PENNSYLVANIA...CENTRAL MARYLAND...PERHAPS THE EASTERN WEST
   VIRGINIA PANHANDLE AND NORTHERN VIRGINIA MAY DIMINISH THIS THREAT.
   
   ..KERR.. 01/30/2013
   
   
   ATTN...WFO...CTP...LWX...RNK...PBZ...RLX...MRX...
   
   LAT...LON   37438176 38288104 39198049 40118000 40757965 41477909
               41877803 41567683 40737689 39247731 38207816 37057945
               36498076 36668202 37028201 37438176