MESO: Mesoscale Discussion 0099

ACUS11 KWNS 301755
SWOMCD
SPC MCD 301754
PAZ000-MDZ000-VAZ000-DCZ000-WVZ000-301930-

MESOSCALE DISCUSSION 0099
NWS STORM PREDICTION CENTER NORMAN OK
1154 AM CST WED JAN 30 2013

AREAS AFFECTED...S-CNTRL/SERN PA...A LARGE PART OF
VA/MD...WASHINGTON DC...PORTIONS OF ERN WV

CONCERNING...SEVERE THUNDERSTORM WATCH 20...

VALID 301754Z - 301930Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 20
CONTINUES.

SUMMARY...THE SVR THREAT IS DIMINISHING ACROSS REMAINING VALID
PORTIONS OF WW20. THE SVR THREAT MAY INCREASE ACROSS PARTS OF THE
AREA FROM THE SW LATER THIS AFTERNOON/EVENING.

DISCUSSION...THE THREAT FOR SVR WINDS IN ASSOCIATION WITH THE
SHALLOW CONVECTIVE BAND THAT ACCOMPANIES A NE/SW-ORIENTED WIND-SHIFT
AXIS FROM S-CNTRL PA INTO SWRN VA CONTINUES TO DIMINISH. REGIONAL
RADAR MOSAIC IMAGERY SUGGEST THAT CONVECTION IS DECREASING IN
ORGANIZATION/INTENSITY AS IT CONTINUES TO OUTRUN STRONGER FORCING
FOR ASCENT ACCOMPANYING A COLD FRONT LOCATED WELL TO THE W. WHILE A
MARGINALLY UNSTABLE AIR MASS WILL CONTINUE TO BE MAINTAINED BY
MODEST LOW-LEVEL THETA-E ADVECTION LEADING THE BAND...IT SHOULD NOT
BE SUFFICIENT FOR ANY MORE THAN ISOLATED 35-45-KT WIND GUSTS IN THE
NEAR TERM. HOWEVER...BY THIS EVENING...ONGOING STRONG TO SEVERE
CONVECTION CURRENTLY CROSSING THE SRN APPALACHIANS MAY EXTEND NEWD
INTO PARTS OF THE MCD AREA -- ESPECIALLY FROM S-CNTRL VA INTO SERN
PA -- WHICH COULD REQUIRE WW ISSUANCE LATER THIS AFTERNOON/EVENING.

..COHEN.. 01/30/2013

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...PHI...AKQ...CTP...LWX...RNK...PBZ...RLX...

LAT...LON 37138159 37848067 38567980 39467893 40577776 40717712
40577638 40087598 39017622 37397742 36807878 36607986
36648130 37138159

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