MESOSCALE DISCUSSION 0856
   NWS STORM PREDICTION CENTER NORMAN OK
   0206 PM CDT WED MAY 29 2013

   AREAS AFFECTED...WEST AND NORTHWEST TX...SOUTHERN OK

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 291906Z - 292100Z

   PROBABILITY OF WATCH ISSUANCE...60 PERCENT

   SUMMARY...CONDITIONS ARE BECOMING MORE FAVORABLE FOR SCATTERED
   THUNDERSTORM DEVELOPMENT ACROSS PARTS OF WESTERN AND NORTHWEST
   TX...AS WELL AS SOUTHERN OK.  WW ISSUANCE MAY BE REQUIRED THIS
   AFTERNOON.

   DISCUSSION...AS OF 19Z...THE SURFACE DRYLINE EXTENDS FROM NEAR AMA
   SOUTHWARD TO EAST OF MAF.  STRONG HEATING HAS BEEN OCCURRING ACROSS
   THE PORTION OF WEST TX EAST OF THE DRYLINE...WHERE MLCAPE VALUES ARE
   CURRENTLY 2500-3000 J/KG.  MID/HIGH CLOUDS ARE ALSO DIMINISHING
   ACROSS SOUTH-CENTRAL OK INTO NORTHWEST TX WHERE INCREASED DIURNAL
   HEATING HAS BEGUN.  THE RESULT IS A RATHER WIDESPREAD AREA OF WEAK
   CAP AND STRONG INSTABILITY.  18Z SOUNDINGS SHOWED VERY STEEP MID
   LEVEL LAPSE RATES ARE PREVALENT THROUGHOUT THE REGION...WHICH MAY
   PROMOTE RAPID THUNDERSTORM INTENSIFICATION ONCE INITIATION OCCURS. 
   EFFECTIVE SHEAR WILL BE FAVORABLE FOR ROTATING STORMS AND STRONG LOW
   LEVEL WINDS MAY BE SUFFICIENT FOR A FEW TORNADOES. 
   HOWEVER...ORIENTATION OF THE UPPER LEVEL FLOW SUGGESTS THAT STORMS
   WILL LIKELY MERGE AND GROW UPSCALE RATHER QUICKLY TODAY...WITH LARGE
   HAIL AND DAMAGING WINDS BEING THE PRIMARY THREATS.

   ..HART/MEAD.. 05/29/2013


   ATTN...WFO...FWD...OUN...SJT...LUB...MAF...

   LAT...LON   33340101 35459828 35389674 32499730 30450031 30900119
               33340101