MESOSCALE DISCUSSION 0798
   NWS STORM PREDICTION CENTER NORMAN OK
   0527 PM CDT TUE MAY 17 2011
   
   AREAS AFFECTED...PA/NJ/MD/DE/VA/WV/DC
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 172227Z - 180030Z
   
   AREAS FROM THE NRN CHESAPEAKE BAY AND DELAWARE BAY INLAND ACROSS
   SERN PA...THE WV PANHANDLE...NRN VA AND D.C...ARE BEING MONITORED
   FOR ORGANIZED TSTM DEVELOPMENT. CONDITIONS IN THESE AREAS COULD
   FAVOR PERSISTENT STORMS WITH THE POTENTIAL FOR LOW LEVEL STORM
   ROTATION AND POSSIBLY A BRIEF TORNADO. HOWEVER...LIMITED STORM
   COVERAGE AND INSTABILITY SUGGEST THAT TEMPORAL NATURE OF THIS THREAT
   IS LIKELY TOO LIMITED FOR A WATCH.
   
   ASCENT ASSOCIATED WITH VORT LOBE PIVOTING THROUGH THE NERN QUADRANT
   OF MID/UPPER LEVEL LOW APPEARS TO HAVE AIDED A BAND OF TSTMS NOW 
   DEVELOPING NNWWD INTO SRN/CNTRL PA. IN THE WAKE OF THIS
   ACTIVITY...LOW LEVEL AIRMASS REMAINS MOIST AND WEAKLY UNSTABLE WITH
   CONFLUENT LOW ELY LEVEL FLOW TOPPED BY 50KT MID LEVEL JET STREAK
   ROTATING AROUND THE UPPER LOW. IF ADDITIONAL DISCRETE STORMS CAN
   INITIATE OVER THE NEXT FEW HOURS...NWWD/NWD-MOVING STORM UPDRAFTS
   WILL EXIST IN KINEMATIC REGIME SUPPORTIVE OF LOW LEVEL STORM
   ROTATION WITH EFFECTIVE SRH AROUND 200 J PER KG AND RELATIVELY LOW
   LFC FAVORING THE POTENTIAL FOR A TORNADO. OVERALL SCENARIO APPEARS
   TO BE TEMPERED BY THE POTENTIAL THAT DEEPER ASCENT MAY BE ON THE
   WANE WITH THE PASSAGE OF THE UPPER VORT LOBE AND ASSOCIATED DPVA.
   NONETHELESS...ONGOING ISOLATED STORMS MAY POSE SOME THREAT AND ANY
   UPWARD TRENDS IN STORM COVERAGE MAY WARRANT A REASSESSMENT.
   
   ..CARBIN.. 05/17/2011
   
   
   ATTN...WFO...PHI...AKQ...CTP...LWX...
   
   LAT...LON   40107604 39717540 39137542 38667579 38447730 38617797
               39037848 39817840 40207768 40107604