MESOSCALE DISCUSSION 2317
   NWS STORM PREDICTION CENTER NORMAN OK
   1142 AM CST FRI DEC 29 2006
   
   AREAS AFFECTED...PORTIONS CENTRAL/SE TX.
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 291742Z - 292015Z
   
   GRADUAL INCREASE IN DEPTH AND COVERAGE OF CONVECTION WILL CONTINUE
   OVER REGION BOUNDED BY MWL...DFW...TYR...HOU...AND SAT THROUGH EARLY
   AFTERNOON.  WATCH ISSUANCE IS POSSIBLE FOR POTENTIAL OF DAMAGING
   GUSTS...ISOLATED HAIL...A FEW TORNADOES.
   
   17Z SFC MESOANALYSIS SHOWS COLD FRONT NEAR A LINE FROM
   ABI...JCT...40 SE DRT.  FRONT SHOULD CONTINUE MOVING SLOWLY EWD
   --10-15 KT...BENEATH STRONGLY MERIDIONAL DEEP-LAYER KINEMATIC
   PROFILES.  STRENGTHENING WARM FRONT EXTENDS FROM COLD
   FRONTAL/OCCLUSION POINT NEAR ABI SEWD TO BETWEEN AUS-ACT...THE SSEWD
   PAST HOU/GLS AREA.  WARM FRONT SHOULD DRIFT/PROPAGATE NWD.  WARM
   SECTOR AIR MASS BETWEEN THESE FRONTS WILL BECOME INCREASINGLY
   UNSTABLE AND BUOYANT OVER NEXT SEVERAL HOURS FROM COMBINATION OF
   WAA...MOIST ADVECTION AND MUTED DIABATIC SFC HEATING.  RELATED
   WEAKENING OF CINH WILL PERMIT CONVECTION TO DEEPEN VERTICALLY...AND
   EFFECTIVE LIFTED PARCELS TO BECOME ROOTED AT SFC...BASED ON TIME
   SERIES OF RUC AND WRF FCST SOUNDINGS.  MLCAPES 500-1200 J/KG WILL BE
   COMMON...AMIDST FAVORABLE VERTICAL SHEAR PROFILES FOR SUPERCELLS.
   
   CYCLONIC SHEAR ALREADY HAS BEEN NOTED IN RELATIVELY SHALLOW
   CONVECTION NEAR TX COAST...AND ROTATION POTENTIAL REGIONALLY WILL
   INCREASE WITH CONTINUED DEEPENING OF CONVECTION...LOSS OF SBCINH AND
   INCREASING INSTABILITY.  THIS TREND WILL BE SUPPORTED BY 40-50 KT
   EFFECTIVE SHEARS AND 300-600 J/KG OF 0-1 KM SRH.  DISCRETE SUPERCELL
   PROBABILITY IS GREATEST IN FREE WARM SECTOR...E OF RELATIVELY STRONG
   BAND OF FORCING ASSOCIATED WITH COLD FRONT.  TSTMS CROSSING WARM
   FRONT MAY HAVE ENHANCED TORNADO PROBABILITIES...AS THEY INTERACT
   WITH ASSOCIATED RELATIVE PEAK OF LOW LEVEL VORTICITY...SHEAR AND
   ASCENT.
   
   ..EDWARDS.. 12/29/2006
   
   
   ATTN...WFO...HGX...FWD...EWX...SJT...
   
   30169921 30399946 31349922 32429904 32679802 32259716
   31749569 30649505 29859533 29329657 29509836 29799886