MESOSCALE DISCUSSION 0508
   NWS STORM PREDICTION CENTER NORMAN OK
   1144 PM CDT FRI APR 17 2009
   
   AREAS AFFECTED...PARTS OF S TX
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 180444Z - 180545Z
   
   THE THREAT FOR MAINLY LARGE HAIL WILL EXIST WITH ONGOING STORM.  DUE
   TO THE ISOLATED NATURE OF THE THREAT...NO WW IS ANTICIPATED.
   
   AN ISOLATED...LEFT-MOVING SUPERCELL HAS RECENTLY EVOLVED FROM A
   DECAYING TSTM CLUSTER S OF LRD WITH THIS STORM LOCATED OVER NERN
   WEBB COUNTY AS OF 0430Z.  USING A STORM MOTION OF 205/35 KT...RUC
   PROXIMITY HODOGRAPHS INDICATE EFFECTIVE SRH VALUES OF -150 TO -200
   M2/S2 WHICH SHOULD CONTINUE TO SUSTAIN THE ANTICYCLONIC SUPERCELL
   WITH A THREAT OF LARGE HAIL.  IMMEDIATE INFLOW AIR MASS REMAINS
   MODERATELY UNSTABLE WITH MOIST BOUNDARY LAYER CONDITIONS AND STEEP
   LAPSE RATES...YIELDING MLCAPE OF 1500-2000 J/KG.  HOWEVER...AS STORM
   CONTINUES NEWD...RUC OBJECTIVE FIELDS SUGGEST A DECREASE IN
   CONVECTIVE INSTABILITY AND INCREASING CONVECTIVE INHIBITION. 
   THUS...EXPECT SUPERCELL TO GRADUALLY WEAKEN PRIOR TO REACHING THE
   SAN ANTONIO AREA.
   
   ..MEAD.. 04/18/2009
   
   
   ATTN...WFO...CRP...EWX...
   
   LAT...LON   28049946 28479929 29099896 29219864 29059839 28479846
               27919873 27749901 27759923 28049946