MESO: Mesoscale Discussion 1754

ACUS11 KWNS 221827
SWOMCD
SPC MCD 221826
NJZ000-DEZ000-MDZ000-VAZ000-PAZ000-NCZ000-DCZ000-WVZ000-222100-

MESOSCALE DISCUSSION 1754
NWS STORM PREDICTION CENTER NORMAN OK
0126 PM CDT THU AUG 22 2013

AREAS AFFECTED...PORTIONS OF CNTRL/ERN NC...CNTRL/ERN VA...CNTRL/ERN
MD...DE...SERN PA...SRN NJ

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 221826Z - 222100Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...AN ISOLATED SVR POTENTIAL WILL EXIST THIS AFTERNOON. WHILE
TRENDS WILL BE MONITORED...THE ISSUANCE OF A WW IS CURRENTLY
UNLIKELY.

DISCUSSION...WATER VAPOR LOOPS INDICATE A MID-LEVEL CYCLONIC
CIRCULATION CROSSING THE PIEDMONT OF MD/VA/NC...WITH A LEADING WARM
CONVEYOR STRUCTURE/MOIST PLUME BEING SHUNTED TOWARD/OFF THE MID
ATLANTIC COAST. RELATIVELY COOL MID-LEVEL CONDITIONS ACCOMPANYING
THE CYCLONE -- E.G. 500-MB TEMPERATURE AROUND -13.5C PER RNK 12Z
RAOB -- ATOP A MOIST/DIURNALLY HEATED BOUNDARY LAYER ARE FOSTERING
MLCAPE ON THE ORDER OF 1000-2500 J/KG WITH LITTLE INHIBITION AS SFC
TEMPERATURES HAVE WARMED INTO THE MIDDLE 80S IN MANY AREAS.

AMIDST A WEAK LOW-LEVEL FLOW REGIME OFFERING LITTLE IN THE WAY OF
CONVERGENCE...DEEPENING PBL AND OROGRAPHIC CIRCULATIONS INVOF THE
APPALACHIANS SHOULD BE THE PRIMARY SOURCES FOR CONVECTIVE
INITIATION...ALONG WITH DIFFERENTIAL-HEATING INDUCED CONVERGENCE
ALONG FRINGES MID-LEVEL CLOUDS IN THE WARM CONVEYOR ALONG THE NC
COASTAL PLAIN. GIVEN THE COMBINATION OF THE AFOREMENTIONED BUOYANCY
AND AROUND 20-30 KT OF MID-LEVEL FLOW PER VWP DATA -- ASSOCIATED
WITH THE ENHANCED HEIGHT GRADIENT AROUND THE CYCLONE -- A FEW
ORGANIZED BANDS OF STORMS COULD ENSUE WITH SPORADIC DMGG
WIND/MARGINALLY SVR HAIL. THIS POTENTIAL MAY BE MAXIMIZED FROM THE
PIEDMONT OF VA/NC EWD TO THE COASTAL PLAIN AND INTO PARTS OF LOWER
SRN MD WHERE THE GREATEST INSTABILITY IS FORECAST TO BE PRESENT.

HOWEVER...WITH STRONGER DCVA MOVING OFF THE COAST...WEAK LOW-LEVEL
MASS CONVERGENCE BENEATH THE MID-LEVEL CYCLONE...AND ONLY MODEST
DEEP SHEAR...IT CURRENTLY APPEARS THAT THE COVERAGE OF THE SVR
THREAT WILL NOT BE SUFFICIENTLY HIGH TO WARRANT A WW...THOUGH TRENDS
WILL BE MONITORED.

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

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

ATTN...WFO...PHI...AKQ...MHX...CTP...LWX...RAH...ILM...RNK...

LAT...LON 37457953 38887820 40077641 39677467 38467489 35297594
34277761 34417896 35188000 36447998 37457953

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