Skip Navigation Links www.nws.noaa.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
Storm Prediction Center
 
   

Search SPC
 

Mesoscale Discussion 2241
MD 2241 graphic
   
   MESOSCALE DISCUSSION 2241
   NWS STORM PREDICTION CENTER NORMAN OK
   0858 PM CDT FRI SEP 17 2004
   
   AREAS AFFECTED...DC...MD...NERN NC...SCNTRL PA...ERN VA...EXTREME
   ERN WV PNHDL
   
   CONCERNING...TORNADO WATCH 836...
   
   VALID 180158Z - 180400Z
   
   ISOLD TORNADOES OR DAMAGING WIND GUSTS WILL CONTINUE TO BE THREATS
   THROUGH 04Z...BUT SEVERE THREATS ARE GRADUALLY DIMINISHING THIS
   EVENING.
   
   THE NUMBER OF DISCRETE LONG-LIVED SUPERCELLS IS BEGINNING TO
   DECREASE THIS EVENING. DIURNAL COOLING IS TAKING A TOLL ON THE
   BUOYANCY OBSERVED IN THE 00Z KIAD SOUNDING AND AIR MASS IS BECOMING
   LESS FAVORABLE TO SUSTAIN UPDRAFTS.  SUFFICIENT INSTABILITY DOES
   EXIST TO SUPPORT A LINE OF TSTMS ASSOCIATED WITH A VORT LOBE
   ROTATING CYCLONICALLY AROUND THE REMNANTS OF IVAN. THIS LINE OF
   STORMS WILL TRANSLATE INTO THE LOWER MD SHORE BY 04Z.  ISOLD CELLS
   MAY CONTINUE TO DEVELOP AHEAD OF THIS LINE AS WELL.
   
   STRONGEST LOW LEVEL HELICITY HAS CONTRACTED TO A SMALL PART OF
   CNTRL/ERN MD INTO SCNTRL PA AND SUGGESTS THAT THE HIGHEST RISK OF A
   TORNADO HAS SHIFTED IN AREAS NORTH/EAST OF THE WASHINGTON D.C. AREA.
    WAKEFIELD VWP SHOWS THAT THE FLOW HAS VEERED IN THE LOWEST GATES
   AND IS RESULTING IN A DEEP SLY UNIDIRECTIONAL REGIME THROUGH THE
   COLUMN...EFFECTIVELY DECREASING SRH.  LINE SEGMENTS HAVE BECOME
   ALIGNED MORE NORMAL TO THIS MEAN WIND AND DAMAGING WIND SEEMS MORE
   OF A RISK FARTHER SOUTH ACROSS SERN VA INTO FAR ERN NC.
   
   GIVEN CONTINUED SURFACE COOLING...PROBABILITIES FOR SEVERE WEATHER
   WILL DECREASE. AFTER 04Z...ANOTHER WEATHER WATCH MAY NOT BE NEEDED
   AS SEVERE WEATHER THREATS SHOULD BECOME ISOLD AT BEST.
   
   ..RACY.. 09/18/2004
   
   
   ATTN...WFO...PHI...AKQ...MHX...CTP...LWX...
   
   35917687 37377719 38597699 39717815 40097812 40137605
   36007540 
   
Top/All Mesoscale Discussions/Forecast Products/Home