[MCD] SWOMCD

[Mesoscale Convective Discussions]

ACUS11 KWNS 242307
SWOMCD
SPC MCD 242307 
ALZ000-MSZ000-LAZ000-TNZ000-ARZ000-250030-

MESOSCALE DISCUSSION 2271
NWS STORM PREDICTION CENTER NORMAN OK
0607 PM CDT SAT SEP 24 2005

AREAS AFFECTED...ERN LA...MUCH OF MS EXTREME WRN TN AND CNTRL/SRN AR

CONCERNING...TORNADO WATCH 815...816...

VALID 242307Z - 250030Z

TS RITA WAS CENTERED VCNTY KSHV LATE THIS AFTN WITH STRONGEST
PRESSURE FALLS LOCATED ACROSS SERN OK/SWRN AR. AGEOSTROPHIC
RESPONSE IN THE LOW-LEVELS HAS RESULTED IN A BACKED FLOW REGIME
ACROSS CNTRL/NRN MS...NERN LA AND SRN AR WITH VERY STRONG 0-3KM
SHEAR. 

SEVERAL SURFACE TROUGHS ARE ROTATING ABOUT RITA WITH TWO PRIMARY
CONVERGENCE ZONES DRIVING TSTM BANDS: ONE FROM CNTRL AR ACROSS CNTRL
MS AND ANOTHER FROM NERN LA INTO SWRN MS.  AS THE STORMS TRANSLATE
NWD INTO THE VERY STRONG LOW-LEVEL SHEAR...SEVERAL TORNADOES HAVE
BEEN REPORTED. AS RITA CONTINUES TO MOVE NWD...THE FAVORABLY
SHEARED ENVIRONMENT WILL EDGE NWD.  BUT...OUTER SPIRAL BANDS/TSTMS
MAY TEND TO WEAKEN SOMEWHAT LATER THIS EVENING AS THE BOUNDARY LAYER
STABILIZES...WITH CONVECTION CONTRACTING TOWARD THE CENTER.  THIS
PROCESS MAY BE SLOWER TO OCCUR THAN NORMALLY EXPECTED...SO A
LINGERING TORNADO THREAT MAY LAST INTO THE LATE EVENING ACROSS AT
LEAST NWRN MS...AND PARTS OF ERN AR.  THIS MAY NECESSITATE
ADDITIONAL WATCHES AFTER 02Z.  

ELSEWHERE...THE VEERING LOW-LEVEL FLOW REGIME AND DECREASING
INSTABILITY OVER THE LAND WILL RESULT IN A DIMINISHING TORNADO
THREAT ACROSS SRN LA AND SRN MS.  CONVECTION MAY INCREASE OVER THE
WATER AND MOVE TOWARD THE SHORELINE LATER IN THE EVENING. 
BUT...THIS CONVECTION WILL LIKELY DIMINISH AS IT APPROACHES/MOVES
OVER THE LAND.

..RACY.. 09/24/2005

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

ATTN...WFO...MOB...MEG...JAN...LIX...LZK...SHV...

29899104 31439171 32169261 34289348 35839337 35718976
34348926 29868787 

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