[MCD] SWOMCD

Wed Apr 26 08:14:42 UTC 2006

ACUS11 KWNS 260811
SWOMCD
SPC MCD 260811 
LAZ000-TXZ000-260945-

MESOSCALE DISCUSSION 0666
NWS STORM PREDICTION CENTER NORMAN OK
0311 AM CDT WED APR 26 2006

AREAS AFFECTED...PORTIONS SW TX...CENTRAL/SRN LA.

CONCERNING...SEVERE THUNDERSTORM WATCH 253...254...

VALID 260811Z - 260945Z

THREAT FOR ELEVATED SEVERE TSTM DEVELOPMENT PERSISTS BEHIND SFC COLD
FRONT ACROSS MOST OF SE TX...IN AREA OF FAVORABLE BUOYANCY AND SHEAR
ALOFT THAT IS ROOTED ATOP FRONTAL SFC. TSTMS N HOU HAVE PRODUCED
HAIL UP TO 2 INCHES DIAMETER WITHIN PAST 1-2 HOURS.  MORE LARGE HAIL
IS EXPECTED FROM MOST VIGOROUS TSTMS IN LARGE AREA OF CONVECTION
COVERING MUCH OF TX/LA S OF A LINE FROM 60 WNW HOU...LFK...POE. 
ADDITIONAL DEVELOPMENT IS POSSIBLE FARTHER W AND SW ACROSS WW...ALSO
N OF SFC COLD FRONT.  MODIFIED RUC SOUNDINGS INDICATE STEEP MIDLEVEL
LAPSE RATES PERSIST ACROSS THIS AREA...WITH BROAD PLUME OF MOIST
ASCENT ATOP STABLE FRONTAL LAYER.  ELEVATED MUCAPES 1500-2500 J/KG
ARE COMMON IN AREAS NOT STABILIZED BY RECENT CONVECTION.  DEEP-LAYER
SHEAR THROUGH BUOYANT LAYER STRENGTHENS WITH SWWD EXTENT ALONG
MID/UPPER TX COASTAL PLAIN...RANGING FROM APPROXIMATELY 35 KT AROUND
HOU TO OVER 60 KT NEAR VCT.  THIS INDICATES POTENTIAL FOR ANY NEW
DEVELOPMENT OVER TX COASTAL PLAIN TO ROTATE AND PRODUCE
LARGE/DAMAGING HAIL.

PORTIONS SWRN/S-CENTRAL LA NOW UNDER WW 253 EWD ACROSS PORTIONS
S-CENTRAL/SERN LA WILL BE MONITORED FOR ADDITIONAL WW. BESIDES MCS
SPREADING ACROSS SRN PORTION WW 253...ISOLATED SUPERCELL HAS
DEVELOPED AND INTENSIFIED QUICKLY OVER TERREBONNE COUNTY ALONG
BOUNDARY BETWEEN OUTFLOW-OVERTURNED AIR INLAND...AND MARINE AIR MASS
ADVECTING INLAND FROM GULF.  LOW LEVEL SHEAR ENHANCEMENTS ASSOCIATED
WITH MARINE BOUNDARY WITHIN ABOUT 50 NM OF COAST SUPPORT SUPERCELL
POTENTIAL DESPITE MRGL MIDLEVEL WINDS. LOW 70S F SFC DEW POINTS
ALONG/S OF THAT BOUNDARY CONTRIBUTE TO SFC-BASED BUOYANCY WITH
MLCAPES 2000-3000 J/KG.

..EDWARDS.. 04/26/2006

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

ATTN...WFO...LIX...LCH...SHV...HGX...CRP...EWX...

28859756 29399772 29979760 30359692 31399475 31469237
29829039 29279019 29089054 29459212 28989514 28639650 

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