MESO: Mesoscale Discussion 0857

ACUS11 KWNS 230734
SWOMCD
SPC MCD 230734
FLZ000-ALZ000-MSZ000-230930-

MESOSCALE DISCUSSION 0857
NWS STORM PREDICTION CENTER NORMAN OK
0234 AM CDT SAT MAY 23 2009

AREAS AFFECTED...EXTREME SWRN AL...EXTREME SERN MS AND THE WRN FL
PANHANDLE

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 230734Z - 230930Z

THREAT FOR ISOLATED STRONG WIND GUSTS AND PERHAPS A BRIEF TORNADO OR
TWO IS EXPECTED TO REMAIN CONFINED TO COASTAL AREAS OF EXTREME SWRN
AL...SERN MS THROUGH THE WRN FL PANHANDLE.

EARLY THIS MORNING THE CENTER OF A LOW PRESSURE AREA WAS LOCATED
ABOUT 60 MILES OFF THE SWRN AL COAST. CONVECTIVELY ACTIVE
CONVERGENCE BAND SITUATED NORTH AND EAST OF THE CENTER WITH AN
EMBEDDED MESO-LOW CIRCULATION ABOUT 15-20 MILES OFFSHORE IS MOVING
NNWWD AT 10-15 KT. OTHER MORE SHALLOW CONVECTION IS DEVELOPING
FARTHER EAST ALONG OUTER CONVERGENCE BANDS NEAR COASTAL AREAS OF THE
FL PANHANDLE. TREND HAS BEEN FOR HODOGRAPHS TO INCREASE IN SIZE AS
SURFACE LOW AND ITS ATTENDANT ELY LOW LEVEL JET DEVELOP NWD. VWP
DATA FROM MOBILE INDICATE 200 M2/S2 0-1 KM HELICITY BASED ON
OBSERVED STORM MOTION...AND STORMS CONTINUE TO SHOW OCCASIONAL
UPDRAFT ROTATION. OVERALL TENDENCY HAS BEEN FOR ACTIVITY TO SHOW
SOME SIGNS OF WEAKENING AS IT MOVES OVER THE SLIGHTLY COOLER SHELF
WATERS CLOSER TO SHORE. LOW LEVEL SHEAR WILL REMAIN SUFFICIENT FOR A
THREAT OF AN ISOLATED TORNADO OR TWO...BUT LIMITED INSTABILITY
INLAND SUGGESTS ANY SEVERE THREAT WILL BE VERY ISOLATED AND CONFINED
TO COASTAL AREAS.

..DIAL.. 05/23/2009

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

ATTN...WFO...TAE...MOB...LIX...

LAT...LON 30368752 30288857 30758817 30668648 30358581 30108594
30288655 30368752

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