SWOMCD
SPC MCD 151613
GAZ000-FLZ000-ALZ000-151845-
MESOSCALE DISCUSSION 0229
NWS STORM PREDICTION CENTER NORMAN OK
1113 AM CDT SUN MAR 15 2009
AREAS AFFECTED...PORTIONS FL PANHANDLE...SERN AL...SWRN GA.
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 151613Z - 151845Z
BAND OF CONVECTION FCST TO MOVE SLOWLY EWD ACROSS DISCUSSION AREA
THROUGH REMAINDER MORNING INTO AFTERNOON. SVR POTENTIAL APPEARS TOO
MRGL/CONDITIONAL FOR WW...THOUGH BRIEF TORNADO CANNOT BE RULED OUT
WITH EMBEDDED SUPERCELL OR LEWP/BOW CIRCULATIONS. STG GUSTS ALSO
MAY OCCUR IN VERY ISOLATED/LOCALIZED FASHION WITH LEWP/BOW FEATURES.
HOWEVER...LACK OF BOTH DRY AIR IN LOW LEVELS AND OF MORE ROBUST
UPDRAFT BUOYANCY INDICATES THAT ORGANIZED SVR WIND POTENTIAL WILL
REMAIN VERY SLIM AND CONDITIONAL.
AT 16Z...CONVECTIVE BAND -- CONSISTING OF NUMEROUS SHOWERS AND
ISOLATED TSTMS -- WAS EVIDENT FROM CENTRAL GA SWWD ACROSS
BARBOUR/BALDWIN COUNTIES AL...CROSSING PORTIONS ESCAMBIA/SANTA ROSA
COUNTIES FL. SFC ANALYSIS SHOWS WAVY WARM FRONT FROM CENTRAL
POTIONS GA COAST GENERALLY WWD ACROSS S-CENTRAL GA THEN NWWD TO JUST
N ABY...INTERSECTING CONVECTIVE BAND. NET EWD MOTION OF CONVECTION
IS APPROXIMATELY 20 KT...THOUGH SOME DECELERATION IS POSSIBLE DURING
MID-DAY/EARLY AFTERNOON HOURS. VIS IMAGERY SHOWS BREAKS IN LOW
CLOUDS IN FOREGOING WARM SECTOR...WHEREIN ASSOCIATED/GRADUAL SFC
HEATING WILL OFFSET WEAK LAPSE RATES ALOFT ENOUGH TO BOOST MLCAPES
INTO 500-1000 J/KG RANGE THROUGH 18Z. NRN EDGE OF SFC-BASED
BUOYANCY IS EXPECTED TO ERODE INLAND PERHAPS AS FAR AS SWRN
GA...ALONG AND SW OF WARM FRONT. LOW-LEVEL VERTICAL SHEAR PROFILES
WILL BE MRGLLY FAVORABLE -- BUT WITH SLIGHT TENDENCY TO WEAKEN WITH
TIME. THIS TREND WILL BE LATED TO VEERING OF BOTH SFC WINDS AND
EXPECTED WEAKENING OF LLJ...EACH OF WHICH ALSO WILL ACT TO MINIMIZE
DIRECTIONAL SHEAR...SHRINK LOW LEVEL HODOGRAPHS SLIGHTLY...AND FAVOR
CONTINUED DOMINANCE OF LINEAR CHARACTER OF CONVECTION. OTHER THAN
MRGL LOW LEVEL SRH...LIMITING FACTOR FOR BETTER ORGANIZED TORNADO
POTENTIAL WILL BE LINEAR STORM MODE. DEEP-LAYER SHEAR WILL BE
FAVORABLE WITH 35-45 KT EFFECTIVE SHEAR PERSISTING AT LEAST THROUGH
EARLY-MID AFTERNOON.
..EDWARDS.. 03/15/2009
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...FFC...TAE...BMX...MOB...
LAT...LON 30228768 32278448 29588502 29688520 29668536 29848544
29908535 30298604 30398659 30308725 30228768
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