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Mesoscale Discussion 2238
MD 2238 graphic
   
   MESOSCALE DISCUSSION 2238
   NWS STORM PREDICTION CENTER NORMAN OK
   0519 PM CDT FRI SEP 17 2004
   
   AREAS AFFECTED...CNTRL MD...ERN WV PNHDL...NRN/ERN VA...DC...ERN NC
   
   CONCERNING...TORNADO WATCH 833...834...
   
   VALID 172219Z - 180015Z
   
   THREATS FOR A TORNADO OR TWO WILL INCREASE FOR THE WASHINGTON D.C.
   AREA THROUGH 00Z.  OTHERWISE...TORNADO WATCH 833 AND 834 WILL BE IN
   EFFECT THROUGH 00Z FOR THE REMAINDER OF CNTRL MD...ERN WV
   PNHDL...NRN/ERN VA AND ERN NC FOR THE THREAT FOR ISOLD TORNADOES. 
   NEW TORNADO WATCHES WILL PROBABLY BE NEEDED BEFORE 00Z.
   
   SEVERAL WELL-DEFINED SUPERCELLS HAVE BEEN MOVING NWD AT AROUND 25
   KTS IN A BAND ARCING FROM THE EXTREME ERN WV PNHDL SWD INTO CNTRL
   VA.  ANOTHER BAND OF TSTMS WAS BEGINNING TO APPROACH THE POTOMAC
   RIVER FROM NEAR STERLING SWD TO EAST OF FREDERICKSBURG AND WILL BE
   IMPACTING THE WASHINGTON D.C. AREA THROUGH 00Z.
   
   MESOANALYSIS SHOWS THAT THE AREA ALONG THE POTOMAC RIVER EWD INTO
   CNTRL MD HAD WARMED TO NEAR 80F WITH DEW POINTS IN THE MID 70S. 
   THUS...IT IS REASONABLE TO EXPECT THE TSTM BAND APPROACHING THE
   RIVER WILL BE MAINTAINED AND POSSIBLY INCREASE AS STRONGEST PRESSURE
   FALLS TRANSLATE NWD FROM SERN VA.  USING A STORM MOTION 185/23
   KTS...THE SRH VALUES ON THE STERLING VWP WERE IN EXCESS OF 180 M2/S2
   IN THE LOWEST 1 KM.  THUS...POTENTIAL FOR TORNADOES WILL EXIST FOR A
   FEW MORE HOURS...AND IN PARTICULAR THE WASHINGTON D.C. AREA THROUGH
   00Z.
   
   OTHERWISE...BAND OF TSTMS MOVING NEWD THROUGH CNTRL VA WILL MOVE
   INTO ERN VA...CNTRL/SRN MD AND ADJACENT CHESAPEAKE BAY IN THE NEXT
   FEW HOURS.  THOUGH A DECREASE IN THE DISCRETE CELLS ARE EXPECTED
   AFTER SUNSET...IT IS NOT ENTIRELY CLEAR THAT THE TORNADO THREATS
   WILL DECREASE. THUS...NEW TORNADO WATCH REPLACEMENTS WILL PROBABLY
   BE NECESSARY BEFORE 00Z FOR PARTS OF THE REGION.
   
   ..RACY.. 09/17/2004
   
   
   ATTN...WFO...PHI...AKQ...MHX...CTP...LWX...RAH...
   
   34987733 39737858 39707641 34967540 
   
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