MESOSCALE DISCUSSION 0905
   NWS STORM PREDICTION CENTER NORMAN OK
   0529 PM CDT TUE MAY 13 2008
   
   AREAS AFFECTED...PARTS OF THE TX EDWARDS PLATEAU/HILL COUNTRY
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 132229Z - 140000Z
   
   THE SEVERE THREAT APPEARS TO BE INCREASING ACROSS REGION.  PORTIONS
   OF WW 311 ARE BEING EXTENDED SOUTHWARD/WESTWARD.  AN ADDITIONAL WW
   IS POSSIBLE.
   
   THE VIGOROUS UPSTREAM SOUTHERN BRANCH CLOSED LOW/SHORT WAVE IMPULSE
   IS STILL OVER THE SOUTHERN PLATEAU...BUT BEGINNING TO TURN TOWARD
   THE SOUTHERN ROCKIES/HIGH PLAINS REGION.  AND...AS EASTWARD
   PROGRESSION CONTINUES...THE BROAD/DIFFUSE DRY LINE IS EXPECTED TO
   RETREAT WESTWARD ACROSS THE EDWARDS PLATEAU REGION OF SOUTHWEST
   TEXAS LATER THIS AFTERNOON/EVENING.  
   
   HOWEVER...AN IMPULSE EMANATING FROM THE SUBTROPICAL STREAM IS
   ALREADY BEGINNING TO LIFT THROUGH THE TEXAS BIG BEND REGION. 
   AND...ASSOCIATED FORCING APPEARS TO BE SUPPORTING STRONG/SEVERE
   STORMS NEAR/NORTH OF JUNCTION...AS WELL AS OFF THE HIGHER TERRAIN OF
   THE MEXICAN PLATEAU...TO THE SOUTH/WEST OF DEL RIO.  INCREASING
   CONVECTIVE DEVELOPMENT APPEARS POSSIBLE ACROSS THIS GENERAL AREA
   INTO EARLY EVENING.  IN THE PRESENCE OF MODERATE TO STRONG DEEP
   LAYER SHEAR BENEATH 40 KT SOUTHWESTERLY 500 MB FLOW...STEEP LAPSE
   RATES ARE CONTRIBUTING TO MODERATE TO STRONG INSTABILITY FAVORABLE
   FOR SUPERCELLS.  THE RISK FOR LARGE HAIL APPEARS THE PRIMARY THREAT
   INITIALLY...BUT THERMODYNAMIC PROFILES SUGGEST THE POTENTIAL FOR
   DAMAGING DOWNBURSTS WITH SUBSTANTIAL EVAPORATIVE COOLING POSSIBLE
   NEAR THE HEAVIER PRECIPITATION CORES.
   
   ..KERR.. 05/13/2008
   
   
   ATTN...WFO...CRP...EWX...SJT...MAF...
   
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