[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 281758
SWOMCD
SPC MCD 281757
NCZ000-SCZ000-TNZ000-GAZ000-ALZ000-MSZ000-282030-

MESOSCALE DISCUSSION 1631
NWS STORM PREDICTION CENTER NORMAN OK
1257 PM CDT SAT JUL 28 2012

AREAS AFFECTED...PORTIONS SRN/ERN TN...NRN AL...EXTREME NERN
MS...NRN GA...WRN NC...NWRN SC.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 281757Z - 282030Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...WIDELY SCATTERED TO SCATTERED TSTMS IN CLUSTERS AND SMALL
BANDS ARE POSSIBLE IN THIS CORRIDOR.  MOST GUSTS SHOULD REMAIN BELOW
SVR LIMITS...BUT STILL CAPABLE OF SPORADIC WIND DAMAGE.  COLD-POOL
AGGREGATION MAY LEAD TO LOOSELY ORGANIZED/FORWARD-PROPAGATING TSTM
BAND INTO PORTIONS NRN MS/AL/GA BEFORE EVENING WEAKENING.

DISCUSSION...SFC MESOANALYSIS SHOWED WEAK/RESIDUAL COLD FRONT AND
RELATED CONVERGENCE ZONE FROM EXTREME WRN/SWRN VA SWWD OVER SRN MID
TN AND SWRN TN.  THIS FEATURE WAS MOVING SWD TO SEWD ABOUT 10
KT...AND CHARACTERIZED MAINLY BY THETAE GRADIENT RELATED TO DRYING
TO ITS N.  THAT BOUNDARY...AND HEATING OF HIGHER TERRAIN NEARBY FROM
SWRN VA THROUGH ERN TN AND WRN NC...WILL BE PRIMARY FOCI FOR
DEVELOPMENT OF TSTMS OVER THIS SWATH DURING NEXT FEW HOURS.

DEEP-LAYER SHEAR WILL STRENGTHEN WITH EWD EXTENT ACROSS TN...WITH
EFFECTIVE SHEAR MAGNITUDES 20-30 KT ACROSS SRN TN AND 30-40 KT OVER
MTNS OF ERN TN/WRN NC.  MAIN MODE ACCORDINGLY SHOULD BE
MULTICELLULAR.  HOWEVER...MOISTURE CHANNEL IMAGERY INDICATES STG
DRYING ALOFT ACROSS MUCH OF WRN NC/ERN TN AREA...BEHIND MID-UPPER
TROUGH...AND TSTM COVERAGE ULTIMATELY MAY BE LESS THERE RELATIVE TO
FARTHER W IN TN VALLEY REGION.  PREFRONTAL BOUNDARY-LAYER AIR MASS
ACROSS THIS REGION IS CHARACTERIZED BY LOWER-ELEVATION DEW POINTS
COMMONLY 70S F.  THAT MOISTURE COMBINES WITH STG INSOLATION TO
OFFSET WEAK LAPSE RATES ALOFT...YIELDING 1500-2500 J/KG MLCAPE IN
FCST SOUNDINGS.

..EDWARDS/CORFIDI.. 07/28/2012

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

ATTN...WFO...RNK...GSP...MRX...FFC...OHX...BMX...HUN...MEG...

LAT...LON   34278540 34148801 34598882 35138886 35388831 35718467
            36278262 36538186 36328102 35088158 34348345 34268509
            34278540



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