MESOSCALE DISCUSSION 2245
   NWS STORM PREDICTION CENTER NORMAN OK
   0848 AM CST THU DEC 20 2007
   
   AREAS AFFECTED...SRN LA...SW MS
   
   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 
   
   VALID 201448Z - 201545Z
   
   AN ISOLATED TORNADO THREAT AND WIND DAMAGE POTENTIAL IS POSSIBLE
   WITH THUNDERSTORMS ONGOING IN SCNTRL LA AND SW MS AND WITH NEW
   STORMS THAT INITIATE LATER THIS MORNING. THE THREAT MAY INCREASE
   WITH TIME THIS MORNING AS SFC TEMPS WARM AND LARGE-SCALE ASCENT
   MOVES THROUGH AREA. A WW MAY BE NEEDED THIS MORNING ACROSS THE
   REGION.
   
   THE LATEST SFC ANALYSIS SHOWS A 1008 MB SFC LOW ACROSS FAR NE TX
   WITH A COLD FRONT EXTENDING SWWD ACROSS ERN AND SOUTH TX. AHEAD OF
   THE FRONT...A MOIST AIRMASS EXISTS WITH 60+ SFC DEWPOINTS. WARM
   ADVECTION IS OCCURRING WITH 40-50 KT LOW-LEVEL JET ORIENTED FROM SW
   TO NE ACROSS SE TX AND CNTRL LA. THIS COMBINED WITH INCREASING
   LARGE-SCALE ASCENT SHOULD SUPPORT CONTINUED THUNDERSTORM
   DEVELOPMENT...THOUGH THE STORMS MAY REMAIN SLIGHTLY ELEVATED. THE
   LCH 12Z SOUNDING SHOWED ABOUT 60 KT OF VERTICAL SHEAR WITH 30 KT OF
   0-1KM SHEAR SUGGESTING THE SHEAR ENVIRONMENT WILL BE STRONG ENOUGH
   FOR AN ISOLATED TORNADO THREAT. HOWEVER...THE GREATER THREAT SHOULD
   BE WIND DAMAGE ESPECIALLY AS THUNDERSTORMS INITIATE SOUTH OF THE
   CURRENT BAND OF STORMS WHERE SFC TEMPS ARE WARMER AND INSTABILITY
   SLIGHT GREATER.
   
   ..BROYLES.. 12/20/2007
   
   
   ATTN...WFO...JAN...LIX...LCH...
   
   29939105 29919316 30169354 30609358 30959306 31319179
   31419131 31429072 31249031 30828988 30348985 29809006