MESO: Mesoscale Discussion 1321

ACUS11 KWNS 302027
SWOMCD
SPC MCD 302027
MDZ000-DCZ000-VAZ000-WVZ000-NCZ000-TNZ000-KYZ000-302300-

MESOSCALE DISCUSSION 1321
NWS STORM PREDICTION CENTER NORMAN OK
0327 PM CDT SAT JUN 30 2012

AREAS AFFECTED...CNTRL/SRN APPALACHIANS AND ADJACENT PIEDMONT

CONCERNING...SEVERE POTENTIAL...SEVERE THUNDERSTORM WATCH LIKELY

VALID 302027Z - 302300Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...ISOLATED TSTMS SHOULD FORM WITHIN A HOT/DEEPLY-MIXED AIR
MASS FROM PARTS OF ERN KY TO WRN VA. ALTHOUGH IT REMAINS UNCLEAR HOW
CONVECTION WILL EVOLVE...POTENTIAL FOR CLUSTERING AMIDST MODERATE TO
STRONG DEEP-LAYER W/NWLYS SHOULD BE SUFFICIENT FOR ISOLATED TO
WIDELY SCATTERED DAMAGING WIND EVENTS THIS EVENING.

DISCUSSION...GROWING CU WAS NOTED FROM ERN KY TO WRN VA IN RECENT
VISIBLE SATELLITE IMAGERY...WITHIN A HOT AIR MASS CHARACTERIZED BY
SURFACE TEMPERATURES IN THE MIDDLE 90S TO AROUND 102. ALTHOUGH
SURFACE DEW POINTS HAVE LARGELY MIXED INTO THE UPPER 50S TO MIDDLE
60S...MODIFIED 18Z IAD RAOB AND PREVIOUS GENERATION RUC VERSION OF
SFCOA WOULD SUPPORT MODERATE BUOYANCY WITH MLCAPE OF 1000-2500 J/KG.
DEEP-LAYER SPEED SHEAR WAS STRONG IN THE 18Z IAD RAOB IN ASSOCIATION
WITH A WEAK IMPULSE PROGRESSING ACROSS ERN PA INTO NJ. ALTHOUGH FLOW
WEAKENS SOMEWHAT WITH SLY EXTENT...IT SHOULD REMAIN SUFFICIENT FOR
ORGANIZED UPDRAFTS. GIVEN THE STEEP LOW-LEVEL LAPSE
RATES...CONGLOMERATION OF COLD POOLS SHOULD FAVOR UPSCALE GROWTH
INTO ONE OR MORE CLUSTERS. PRIMARY RISK WILL LIKELY BE DAMAGING
WINDS.

..GRAMS/THOMPSON/HART.. 06/30/2012

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

ATTN...WFO...AKQ...LWX...RAH...RNK...RLX...MRX...JKL...

LAT...LON 37468258 37508140 37848033 38787896 39437812 39477760
39317715 39097699 38537707 37067818 36297895 36087998
36098102 36218174 36568229 36908281 37468258

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