MESOSCALE DISCUSSION 0488
   NWS STORM PREDICTION CENTER NORMAN OK
   0731 PM CDT THU APR 16 2009
   
   AREAS AFFECTED...SWRN TX
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 170031Z - 170200Z
   
   TSTM POTENTIAL APPEARS TO BE INCREASING ACROSS SRN PORTION OF
   TORNADO WATCH 157 SWD TO THE RIO GRANDE.  SHOULD STORMS DEVELOP S OF
   WW...A LOCAL EXTENSION IN AREA MAY BE REQUIRED.  SHOULD STORMS
   DEVELOP AND CROSS THE RIO GRANDE NEAR DRT...A NEW WW WOULD BE
   REQUIRED.
   
   LATEST VISIBLE SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE
   DRYLINE RETREATING WWD THROUGH ECTOR...CRANE...PECOS AND BREWSTER
   COUNTIES...TO THE E OF PACIFIC COLD FRONT ADVANCING EWD THROUGH FAR
   WRN TX.  EXTRAPOLATION OF CURRENT MOTION SUGGESTS A MERGING OF THESE
   BOUNDARIES OVER LOVING OR WINKLER SWD INTO WARD...REEVES...PECOS AND
   BREWSTER COUNTIES WITHIN THE NEXT 1-2 HOURS.  BASED ON 00Z MAF/DRT
   SOUNDINGS...THERMODYNAMIC ENVIRONMENT REMAINS MODERATELY UNSTABLE
   THIS EVENING OWING TO THE PRESENCE OF STEEP LAPSE RATES AND
   INCREASING BOUNDARY LAYER MOISTURE.
   
   WHILE THE CAPPING EML INCREASES WITH SWD EXTENT TOWARD THE RIO
   GRANDE...ENHANCED MESOSCALE CONVERGENCE ALONG THESE COLLIDING
   BOUNDARIES MAY BE SUFFICIENT TO INITIATE ADDITIONAL STORMS...PERHAPS
   IN THE FORM OF A LINE.  SHOULD THIS OCCUR...AN AREAL EXTENSION OF WW
   157 MAY BE REQUIRED.
   
   FARTHER SE...TSTMS ARE ATTEMPTING TO BECOME SUSTAINED ALONG THE
   HIGHER TERRAIN W OF DRT AS OF 0020Z.  00Z DRT SOUNDING WAS RATHER
   IMPRESSIVE WITH AN MLCAPE OF 2500 J/KG...0-1 KM SHEAR OF 25-30 KT
   AND DEEP-LAYER SHEAR OF 50-60 KT.  AS MENTIONED ABOVE...A STRONG CAP
   WAS OBSERVED AROUND 800 MB SO THERE IS SOME QUESTION IF DEVELOPING
   STORMS WILL BECOME SUSTAINED AS THEY MOVE OFF THE HIGHER TERRAIN
   INTO THE RIO GRANDE VALLEY.  GIVEN THE ENVIRONMENT VERY CONDUCIVE TO
   SUPERCELLS...A WW WOULD HAVE TO BE CONSIDERED IF ANY STORMS CAN
   DEVELOP AND MOVE TOWARD DRT.
   
   ..MEAD.. 04/17/2009
   
   
   ATTN...WFO...EWX...SJT...MAF...
   
   LAT...LON   29870330 30750333 31300318 31610287 31020210 30220151
               29890062 29290030 29180067 29570118 29830185 29570307
               29870330