[BNAWX] Severe Storm Outlook Narrative

Tue Jul 24 14:26:33 CDT 2012

ACUS11 KWNS 241926
SWOMCD
SPC MCD 241925
WVZ000-VAZ000-TNZ000-KYZ000-242100-

MESOSCALE DISCUSSION 1571
NWS STORM PREDICTION CENTER NORMAN OK
0225 PM CDT TUE JUL 24 2012

AREAS AFFECTED...CNTRL/ERN KY...SRN WV...SWRN VA...NERN TN

CONCERNING...SEVERE THUNDERSTORM WATCH 509...

VALID 241925Z - 242100Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 509
CONTINUES.

SUMMARY...THE THREAT FOR SVR WIND GUSTS ALONG WITH HEAVY RAINFALL
WILL OCCUR IN ASSOCIATION WITH A MESOSCALE CONVECTIVE SYSTEM MOVING
INTO THE CNTRL APPALACHIANS. ADDITIONAL STORM DEVELOPMENT MAY OCCUR
WEST OF THIS ACTIVITY IN CNTRL KY.

DISCUSSION...THE LEADING EDGE OF AN MCS-RELATED COLD POOL ARCING
FROM CNTRL TO SRN WV AND WWD INTO ERN KY WILL CONTINUE TO SURGE SWD
TOWARD SWRN VA AND SERN KY DURING THE NEXT COUPLE OF HOURS.
REFLECTIVITY DATA SUGGEST WEAKENING OF CONVECTIVE CORES OVER THE
LEADING EDGE OF THE ERN FLANK OF THE COLD POOL. THIS IS THE RESULT
OF LIMITED DOWNSTREAM BUOYANCY ASSOCIATED WITH EARLIER STRATIFORM
PRECIPITATION. HOWEVER...STRONG WIND GUSTS WILL STILL BE POSSIBLE
WITH THE SURGE OF THE COLD POOL OWING TO THE RESIDUAL REAR INFLOW
JET/MESOSCALE CIRCULATION.

MEANWHILE...OVER THE WRN FLANK OF THE COLD POOL...WLY LOW-LEVEL
INFLOW OF GREATER INSTABILITY -- MLCAPE OF 2000-2500 J/KG PER
MODIFIED NASHVILLE 12Z RAOB -- SHOULD MAINTAIN UPDRAFT STRENGTH AND
PERSISTENCE ACROSS ERN KY. SVR WIND GUSTS REMAIN POSSIBLE WITH THIS
ACTIVITY...WHICH COULD SAG SWD INTO NERN TN. THIS MAY BE ADDRESSED
WITH EXPANDING THE WW AREA SOUTHWARD. ALSO...THE WRN SEGMENT OF THE
LINE HAS BECOME ORIENTED LARGELY PARALLEL TO 25-35 KT OF CLOUD-LAYER
FLOW PER JACKSON KY/ROANOKE VA VWP DATA. THIS WILL ALLOW TRAINING OF
MESO-BETA ELEMENTS...ALONG WITH PERSISTENCE OF HEAVY RAINFALL --
1-2-IN/HR RAINFALL RATES.

MEANWHILE...RECENT VISIBLE SATELLITE IMAGES INDICATE A
BOUNDARY-LAYER CUMULUS FIELD SWELLING NEAR AND SOUTH OF A RELATIVELY
SLOWER-MOVING OUTFLOW BOUNDARY. THIS BOUNDARY RECENTLY CROSSED
LEXINGTON AND ALSO EXTENDS FARTHER NW TO 30 NNE OF LOUISVILLE. WITH
OVER 3000 J/KG OF MLCAPE AMIDST LITTLE/NO CINH...AND WITH FORCING
FOR ASCENT OFFERED BY THE OUTFLOW BOUNDARY...SVR STORMS WITH DMGG
WINDS AND HAIL MAY DEVELOP FROM THE CUMULUS FIELD DURING THE NEXT
FEW HOURS.

..COHEN.. 07/24/2012

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

ATTN...WFO...RNK...RLX...MRX...JKL...ILN...LMK...

LAT...LON   37668099 38388047 38448090 38098144 37748238 38068337
            38308449 38378496 38318542 38038574 37558565 36998521
            36558403 36008313 36298210 36908140 37668099

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