MESOSCALE DISCUSSION 0475
   NWS STORM PREDICTION CENTER NORMAN OK
   1131 PM CDT THU APR 12 2007
   
   AREAS AFFECTED...WRN TX INTO THE TX PNHDL
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 131...
   
   VALID 130431Z - 130630Z
   
   THE SEVERE WEATHER THREAT IS EXPECTED TO PERSIST BEYOND 05Z AND A
   NEW WW WILL LIKELY BE REQUIRED.
   
   LATEST SURFACE OBSERVATIONS AND RUC OBJECTIVE FIELDS INDICATE THAT
   LOW-LEVEL MOISTURE AND ATTENDANT INSTABILITY AXES CONTINUE TO
   DEVELOP NWWD THROUGH THE CONCHO VALLEY AND W-CNTRL TX INTO THE
   PERMIAN BASIN AND TX S PLAINS ALONG THE WRN EDGE OF 45-55 KT SSELY
   LLJ.  TSTM AREAL COVERAGE HAS TENDED TO DIMINISH OVER THE PAST
   HOUR...PRESUMABLY AS STRONGER LARGE-SCALE FORCING FOR ASCENT
   ASSOCIATED WITH LEAD SHORT WAVE TROUGH LIFTS NEWD THROUGH NWRN OK
   AND SWRN KS...AND AWAY FROM DEVELOPING INSTABILITY AXIS FARTHER TO
   THE SW.
   
   THIS TREND MAY CONTINUE FOR THE NEXT COUPLE OF HOURS...HOWEVER BY
   07-09Z...MODEL GUIDANCE SUGGESTS THAT LARGE-SCALE FORCING FOR UPWARD
   VERTICAL MOTION WILL REINTENSIFY IN RESPONSE TO APPROACH OF MAIN
   UPPER SYSTEM INTO WRN NM.  AS THIS OCCURS...EXPECT RENEWED TSTM
   DEVELOPMENT NEAR AND N OF QUASI-STATIONARY BOUNDARY CURRENTLY
   EXTENDING FROM SURFACE LOW OVER SERN NM NEWD THROUGH THE TX S PLAINS
   AND THEN MORE EWD THROUGH NWRN TX.  ADDITIONAL STORMS MAY ALSO FORM
   SWD ALONG AND E OF DRYLINE WHICH HAS RETREATED TO JUST W OF THE
   PERMIAN BASIN.
   
   THE PRESENCE OF QUITE STEEP MID-LEVEL LAPSE RATES /8-8.5 C PER KM/
   IN CONJUNCTION WITH THE INCREASING BOUNDARY LAYER MOISTURE WILL
   SUPPORT A CONTINUED INCREASE IN CONVECTIVE INSTABILITY WITH MUCAPES
   APPROACHING 1500-1800 J/KG.  WHEN COUPLED WITH THE STRONGLY SHEARED
   ENVIRONMENT...POTENTIAL WILL EXIST FOR SUPERCELLS CAPABLE OF MAINLY
   LARGE HAIL AND DAMAGING WINDS.
   
   ..MEAD.. 04/13/2007
   
   
   ATTN...WFO...SJT...LUB...AMA...MAF...
   
   32920290 33540303 34780296 35380281 35970196 36000099
   35460033 34400008 33470019 32630038 31890101 32120262