MESO: Mesoscale Discussion 0771

ACUS11 KWNS 221954
SWOMCD
SPC MCD 221953
PAZ000-MDZ000-VAZ000-WVZ000-222100-

MESOSCALE DISCUSSION 0771
NWS STORM PREDICTION CENTER NORMAN OK
0253 PM CDT WED MAY 22 2013

AREAS AFFECTED...WRN/NRN VA...ERN WV PANHANDLE...CNTRL PA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 221953Z - 222100Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...CONVECTION MAY GRADUALLY INCREASE IN INTENSITY AS IT
PROPAGATES SLOWLY EWD OFF THE HIGHER TERRAIN FROM WRN VA INTO CNTRL
PA.

DISCUSSION...BOUNDARY LAYER HAS WARMED MARKEDLY ACROSS WRN VA/MD
INTO PA WHERE SFC-3KM LAPSE RATES ARE NOW ON THE ORDER OF 8.5 C/KM.
OVER THE LAST OR SO A GRADUAL UPWARD TREND IN CONVECTION HAS BEEN
NOTED ACROSS THE CNTRL APPALACHIANS. IF EXPANDING PRECIP SHIELD
MANAGES TO FORCE AN ORGANIZED OUTFLOW BOUNDARY INTO WRN PLUME OF
HIGHER INSTABILITY...IT MAY SERVE AS THE FOCUS FOR STRONG CONVECTION
FROM PORTIONS OF WRN VA...NWD INTO CNTRL PA. GRADUALLY INCREASING
DEEP LAYER SHEAR MAY ULTIMATELY ALLOW CONVECTION ALONG THE EAST
SLOPES TO LOOSELY ORGANIZE AS THEY PROPAGATE NEWD. DAMAGING WINDS
AND PERHAPS SOME LARGE HAIL ARE THE MAIN CONCERNS. UNTIL
OUTFLOW/CONVECTION BECOME BETTER ORGANIZED SEVERE THREAT SHOULD
REMAIN SOMEWHAT ISOLATED.

..DARROW/KERR.. 05/22/2013

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

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

LAT...LON 37478032 41257771 40647596 37437900 37478032

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