MESO: Mesoscale Discussion 1755

ACUS11 KWNS 221851
SWOMCD
SPC MCD 221851
PAZ000-WVZ000-OHZ000-KYZ000-INZ000-ILZ000-222115-

MESOSCALE DISCUSSION 1755
NWS STORM PREDICTION CENTER NORMAN OK
0151 PM CDT THU AUG 22 2013

AREAS AFFECTED...PORTIONS OF CNTRL/SRN/ERN OH...WRN
PA...WV...KY...SRN INDIANA...SERN IL

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 221851Z - 222115Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...AN ISOLATED SVR THUNDERSTORM POTENTIAL WILL EXIST THIS
AFTERNOON...THOUGH THE ISSUANCE OF A WW IS UNLIKELY.

DISCUSSION...SFC OBS SUGGEST THAT A REMNANT/WAVY/QUASI-STATIONARY
OUTFLOW BOUNDARY LIES INVOF THE INTERSTATE 70 CORRIDOR FROM CNTRL IL
INTO CNTRL INDIANA WHERE IT LINKS WITH A DIFFERENTIAL HEATING ZONE
THAT ARCS EWD INTO SWRN/CNTRL OHIO AND INTO N-CNTRL OHIO. ASCENT
ACCOMPANYING THESE FEATURES WILL PROVIDE THE FOCI FOR GREATER
CONVECTIVE COVERAGE THROUGH THE AFTERNOON...AS ISOLATED TO SCATTERED
THUNDERSTORMS DEVELOP ACROSS THE AREA. OTHER STORM DEVELOPMENT WILL
BE SUPPORTED ALONG SUBTLE AXES OF WEAK CONFLUENCE TO THE SE OF THE
BOUNDARY/DIFFERENTIAL HEATING ZONE.

CONTINUED DIABATIC SFC HEATING OF A MOIST BOUNDARY LAYER FEATURING
UPPER 60S AND LOWER 70S SFC DEWPOINTS ARE ALLOWING LOW-LEVEL LAPSE
RATES TO STEEPEN AND MLCAPE VALUES TO REACH AROUND 1000-2000 J/KG
PER MODIFIED 12Z WILMINGTON OH AND PITTSBURGH PA RAOB DATA. MOSTLY
UNIDIRECTIONAL -- ALBEIT WEAK -- WNWLY/NWLY FLOW THROUGH THE CLOUD
LAYER PER AREA VWP DATA MAY FOSTER A FEW LOOSELY ORGANIZED STORM
CLUSTERS WITH MARGINALLY SVR WIND...AND MARGINALLY SVR HAIL CANNOT
BE RULED OUT. HOWEVER...WITH GENERALLY 20 KT OR LESS OF
LOW/MID-LEVEL FLOW...DEEP SHEAR IS WEAK. AND...WITH DEEP FORCING FOR
ASCENT BEING RELATIVELY LIMITED...OVERALL CONVECTIVE ORGANIZATION
AND ANY SVR COVERAGE SHOULD ALSO BE LIMITED.

..COHEN/CORFIDI.. 08/22/2013

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

ATTN...WFO...PBZ...RLX...CLE...JKL...ILN...LMK...IND...PAH...
ILX...LSX...

LAT...LON 37968891 39128913 39858817 39798677 39748499 39828368
40308322 40888328 41288302 41548190 41528098 41388049
39888000 38458034 37758153 37068396 36968608 37308804
37968891

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