MESOSCALE DISCUSSION 0641
   NWS STORM PREDICTION CENTER NORMAN OK
   0655 PM CDT WED APR 27 2011
   
   AREAS AFFECTED...CNTRL/ERN MD...CNTRL VA...N-CNTRL NC
   
   CONCERNING...TORNADO WATCH 240...
   
   VALID 272355Z - 280100Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 240 CONTINUES.
   
   TORNADO THREAT CONTINUES WITHIN WW 240 AS NUMEROUS DISCRETE
   STORMS...MANY OF WHICH ARE EXHIBITING ROTATION AND SPLITTING
   SUPERCELL CHARACTERISTICS...PERSIST WITHIN A BROAD WARM SECTOR FROM
   CNTRL MD SWWD TO N-CNTRL NC. AREA VWP DATA HAS SHOWN STRENGTHENING
   OF LOW-LEVEL FLOW DURING THE PAST HOUR WITH 0-1 KM SHEAR OF 30-40 KT
   BECOMING INCREASINGLY COMMON. LEAD UPPER-LEVEL IMPULSE /EVIDENT IN
   WATER VAPOR IMAGERY/ SHIFTING NE ACROSS THE MID-ATLANTIC SHOULD
   SERVE TO MAINTAIN FORCED ASCENT AND TSTM ACTIVITY THROUGH MUCH OF
   THE EVENING. SUBSIDENCE IN THE WAKE OF THIS IMPULSE SHOULD MITIGATE
   ADDITIONAL DEVELOPMENT S OF ONGOING TSTMS IN N-CNTRL NC.
   
   ..GRAMS.. 04/27/2011
   
   
   ATTN...WFO...PHI...AKQ...CTP...LWX...RAH...RNK...
   
   LAT...LON   36577817 35937912 36298011 37367953 39037798 39787676
               39667615 39147597 38587606 37827649 36937754 36577817