MESOSCALE DISCUSSION 0844
   NWS STORM PREDICTION CENTER NORMAN OK
   0726 PM CDT TUE MAY 28 2013

   AREAS AFFECTED...BIG BEND/MIDDLE RIO GRAND VALLEY OF TX INTO THE
   EDWARDS PLATEAU

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 290026Z - 290230Z

   PROBABILITY OF WATCH ISSUANCE...40 PERCENT

   SUMMARY...STORMS NOW MAINLY CONFINED TO AREAS S/W OF THE RIO GRANDE
   VALLEY MAY EXPAND/SPREAD INTO ADJACENT AREAS OF TX.  WW WOULD BE
   POSSIBLE IN THIS SCENARIO -- THOUGH POTENTIAL REMAINS UNCERTAIN
   ATTM.

   DISCUSSION...LATEST RADAR/SATELLITE IMAGERY SHOWS A CLUSTER OF
   STRONG/SEVERE STORMS JUST E OF THE TX BIG BEND -- OVER NRN MEXICO
   ATTM.  DOWNSTREAM...A RELATIVELY MOIST/MODERATELY UNSTABLE AIRMASS
   IS IN PLACE ACROSS ADJACENT PORTIONS OF TX...BUT EVENING DRT RAOB
   OBSERVED A SUBSTANTIAL CAPPING INVERSION AROUND 800 MB -- WHICH HAS
   THUS FAR SUPPRESSED ANY CONVECTIVE DEVELOPMENT AWAY FROM THE HIGHER
   TERRAIN OF NRN MEXICO.  

   HIGH-RES MODELS FORECAST STORMS TO EVENTUALLY SPREAD EWD INTO TX
   THIS EVENING...AS WARM ADVECTION INCREASES SUBSTANTIALLY IN
   CONJUNCTION WITH NOCTURNAL LOW-LEVEL JET DEVELOPMENT.  AS THE JET
   INCREASES BENEATH MID-LEVEL SWLYS AROUND 30 KT...SHEAR WOULD SUPPORT
   ORGANIZED/ROTATING UPDRAFTS -- AND THUS SEVERE POTENTIAL AND
   POSSIBLY A TORNADO.  HOWEVER...GIVEN CAPPING...THIS THREAT REMAINS
   CONDITIONAL -- AND THUS WE WILL CONTINUE TO MONITOR CONVECTIVE
   EVOLUTION/SEVERE POTENTIAL ACROSS THIS AREA.

   ..GOSS/THOMPSON.. 05/29/2013


   ATTN...WFO...EWX...SJT...MAF...

   LAT...LON   29740149 29760185 29830224 29700266 30480254 30980148
               31140058 31199873 30249830 28979855 28680050 29130068
               29740149