MESOSCALE DISCUSSION 0512
   NWS STORM PREDICTION CENTER NORMAN OK
   1201 PM CDT FRI APR 30 2004
   
   AREAS AFFECTED...NW TX
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL 
   
   VALID 301701Z - 301900Z
   
   SEVERE THREAT IS INCREASING ACROSS NORTHWEST TEXAS.  WW COULD BECOME
   NECESSARY AS EARLY AS 18Z.
   
   LATEST WATER VAPOR LOOPS SUGGEST MID-LEVEL FORCING FOR UPWARD
   VERTICAL MOTION IS INCREASING ACROSS THE SOUTHERN TEXAS PANHANDLE
   INTO NORTHWEST TEXAS.  THIS APPEARS TO BE IN RESPONSE TO WARM
   ADVECTION AT CREST OF AMPLIFYING SHORT WAVE RIDGE...WHICH WILL SHIFT
   EAST NORTHEASTWARD NEXT FEW HOURS...ENHANCING LIFT NEAR COLD FRONT/
   CONVECTIVE OUTFLOW INTERSECTION...NORTHEAST OF ABILENE.  CAP NOW
   INHIBITING SURFACE-BASED STORMS IN WARM SECTOR SHOULD WEAKEN
   SUFFICIENTLY TO SUPPORT RAPID INTENSE CONVECTIVE DEVELOPMENT...
   POSSIBLY AS EARLY AS THE 18-20Z TIME FRAME.  
   
   GIVEN EVOLUTION OF STEEP LAPSE RATE ENVIRONMENT NEAR BOUNDARY
   INTERSECTION...WITH MEAN MIXED LAYER CAPE IN EXCESS OF 2000 J/KG...
   ISOLATED VERY LARGE HAIL APPEARS POSSIBLE IN STRONGEST STORMS. 
   SHEAR PROFILES ARE ALREADY SUFFICIENT FOR SUPERCELLS...AND WILL
   STRENGTHEN THROUGH THE AFTERNOON AS 50+ KT SOUTHWESTERLY MID-LEVEL
   JET SHIFTS EASTWARD ACROSS THE SOUTHERN HIGH PLAINS.  
   
   ISOLATED BRIEF TORNADOES APPEAR POSSIBLE WITH INITIAL ACTIVITY...BUT
   LARGE HAIL IS EXPECTED TO BE PRIMARY THREAT BEFORE LARGER CONVECTIVE
   CLUSTER EVOLVES BENEATH DIFLUENT/DIVERGENT UPPER FLOW REGIME. 
   THEREAFTER...DAMAGING WIND GUSTS SHOULD BECOME INCREASING
   THREAT...WITH DRY MID-LEVELS AND ASSOCIATED STRONG EVAPORATIVE
   COOLING ENHANCING DOWNDRAFTS/SURFACE COLD POOL DEVELOPMENT.
   
   ..KERR.. 04/30/2004
   
   
   ATTN...WFO...FWD...OUN...SJT...
   
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