MESOSCALE DISCUSSION 0482
   NWS STORM PREDICTION CENTER NORMAN OK
   0508 PM CDT FRI APR 13 2007
   
   AREAS AFFECTED...ERN TX INTO WRN LA
   
   CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY 
   
   VALID 132208Z - 132345Z
   
   SUPERCELL AND ATTENDANT TORNADO THREAT IS FORECAST TO INCREASE
   ACROSS DISCUSSION AREA THROUGH 14/00Z AND A TORNADO WATCH WILL
   LIKELY BE REQUIRED.
   
   REGIONAL RADAR AND VISIBLE SATELLITE IMAGERY INDICATE THAT
   CONSIDERABLE FORCING FOR ASCENT IS OCCURRING ALONG PRIMARY LLJ AXIS
   AS EVIDENCED BY WEAK RETURNS OVER SERN TX TRANSITIONING TO ELEVATED
   TSTMS OVER NERN TX INTO NWRN LA AS ISENTROPIC ASCENT FORCES PARCELS
   TO THEIR LFC NEAR/N OF SURFACE WARM FRONT.  18Z LCH/20Z SHV OBSERVED
   SOUNDINGS INDICATED A CAP IN PLACE AROUND 850 MB...HOWEVER THIS
   PERSISTENT FORCING ALONG LLJ AXIS COUPLED WITH A
   MOISTENING/DEEPENING BOUNDARY LAYER ARE LIKELY RESULTING IN EROSION
   OF THIS FEATURE.  INDEED...LATEST SHORT TERM MODEL GUIDANCE SUGGEST
   THAT SURFACE-BASED TSTMS WILL BECOME INCREASINGLY LIKELY ACROSS
   DISCUSSION AREA BETWEEN 13/23Z-14/03Z.
   
   THE COMBINATION OF MLCAPES OF 1000-1500 J/KG COUPLED WITH 40-50 KT
   OF EFFECTIVE BULK SHEAR AND 0-1 KM SRH OF 300-350 M2/S2 INDICATES
   THE HIGH POTENTIAL FOR SUPERCELLS CAPABLE OF TORNADOES...LARGE HAIL
   AND DAMAGING WINDS.
   
   ..MEAD.. 04/13/2007
   
   
   ATTN...WFO...LCH...SHV...HGX...FWD...
   
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