[MCD] SWOMCD

[Mesoscale Convective Discussions]

ACUS11 KWNS 211548
SWOMCD
SPC MCD 211548 
LAZ000-TXZ000-211715-

MESOSCALE DISCUSSION 1991
NWS STORM PREDICTION CENTER NORMAN OK
1048 AM CDT THU SEP 21 2006

AREAS AFFECTED...PORTIONS SE TX...SWRN/S-CENTRAL LA.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 211548Z - 211715Z

BROKEN BAND OF WARM-FRONTAL TSTMS -- INITIALLY EXTENDING FROM SE TX
SEWD ACROSS GULF -- IS FCST TO MOVE NEWD ONSHORE SWRN LA THROUGH
18Z.  ONE OR TWO SUPERCELLS MAY DEVELOP WITH MRGL TORNADO POTENTIAL.
 MAIN LIMITING FACTORS FOR SVR POTENTIAL NEXT COUPLE HOURS WILL BE
NON-DISCRETE CONVECTIVE MODE IN MOST AREAS...AND ALSO SPEED/DEGREE
OF INLAND DESTABILIZATION.  THOUGH WW IS NOT ANTICIPATED SOON...AREA
MAY BECOME MORE FAVORABLE THROUGH AFTERNOON.

SFC ANALYSIS AND VIS SATELLITE IMAGERY INDICATES 15Z MARINE/WARM
FRONT POSITION FROM NEAR HOU ESEWD TO SABINE RIVER MOUTH...TO ABOUT
60 SSW ARA...MOVING NNEWD 15-20 KT...AND BECOMING DIFFUSE W OF HOU. 
MIDLEVEL WINDS AND DEEP-LAYER SHEAR DIMINISH WITH EWD EXTENT ALONG
FRONT...BUT SHOULD INCREASE WITH TIME AS GRADIENTS ALOFT TIGHTEN SE
OF INTENSE WRN KS CYCLONE.  LOW LEVEL HODOGRAPHS ACROSS THIS REGION
ARE LARGEST N OF WARM FRONT...BUT MODIFIED LCH RAOB/VWP DATA AND RUC
SOUNDINGS INDICATE 0-1 KM SRH 100-150 J/KG MAY EXIST ALONG AND S OF
FRONT AS WELL...WHERE SFC-BASED BUOYANCY IS MOST LIKELY TO SHIFT
INLAND FROM GULF.  BUOY DATA AND CRP RAOB INDICATES AIR MASS S OF
FRONT IS CHARACTERIZED VERY RICH AND DEEP LAYER OF LOW LEVEL
MOISTURE...WITH SFC DEW POINTS MID 70S F.  RELATIVELY STABLE LAYER
AROUND 700 MB IS PROGGED TO COOL AS BOUNDARY LAYER
HEATS...CONCURRENT WITH WARM FROPA AND SFC DIABATIC HEATING.  THIS
YIELDS MLCAPES 1000-1500 J/KG ALONG COAST FROM BPT AREA EWD THROUGH
AND SE OF LCH BY 18Z.

..EDWARDS.. 09/21/2006

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

ATTN...WFO...LIX...LCH...SHV...HGX...

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