MESOSCALE DISCUSSION 0888
   NWS STORM PREDICTION CENTER NORMAN OK
   0216 AM CDT FRI MAY 29 2009
   
   AREAS AFFECTED...PORTIONS S TX.
   
   CONCERNING...HEAVY RAINFALL 
   
   VALID 290716Z - 290945Z
   
   SHORT-TERM HEAVY RAIN THREAT WILL CONTINUE WITH MCS AS IT MOVES OUT
   OF SRN HILL COUNTRY OVER SAT-HDO-UVA AREAS...AND PERHAPS FARTHER SSE
   TOWARD COT REGION.  THREAT WILL BECOME MORE UNCERTAIN/CONDITIONAL
   WITH SEWD EXTENT PAST SAT/UVA AREAS.  EXPECT OCCASIONAL 1-2
   INCH/HOUR RATES...LOCALLY/BRIEFLY 2-3 INCHES/HOUR IN HEAVIEST CORES.
   
   
   AS OF 07Z...OUTFLOW-DOMINANT MCS WITH SCATTERED-NUMEROUS TSTMS WAS
   LOCATED ACROSS PORTIONS GILLESPIE/KENDALL COUNTIES SWWD TO NERN
   KINNEY COUNTY.  ACTIVITY SHOULD CONTINUE TO DEVELOP FOR ANOTHER 1-2
   HOURS ATOP EXISTING AND WELL DEVELOPED COLD POOL...ABOVE WHICH 
   INCREASINGLY MOIST INFLOW-LAYER AIR MASS WILL BE FORCED TO LFC. 
   MODIFIED RAOBS AND RUC SOUNDINGS SUGGEST ELEVATED MUCAPE IN
   1000-1500 J/KG RANGE...ROOTED IN MOIST AIR MASS NEAR 850 MB THAT
   SUPPORTS 1.25-1.5 INCH PW PER GPS OBS.  MCS WILL CONTINUE TO EXHIBIT
   MIXED-MODE PROPAGATION -- COLD-POOL/FORWARD...WHILE VEERING 850 MB
   FLOW ALREADY OBSERVED IN DFX VWP SUPPORTS SOME
   REARWARD/PROPAGATIONAL DEVELOPMENT ALSO...WITH MERGING/TRAINING
   POSSIBLE MAINLY OVER SWRN PORTION OF COMPLEX.  NET MOTION SHOULD
   MOVE PREFERRED WRN PORTION OF MCS ACROSS AREA ROUGHLY BOUNDED BY
   COT...UVA...SAT.  OFFSETTING FACTORS WILL INCLUDE INCREASING
   MUCINH...AN FCST WEAKENING TRENDS IN ABSOLUTE AND STORM-RELATIVE 850
   MB WINDS WITH TIME.  THIS LENDS UNCERTAINTY AS TO HOW FAR S AND SE
   HEAVY RAIN THREAT WILL EXTEND TOWARD MIDDLE COAST AND DEEP S
   TX...PROBABILITIES LOWERING AND BECOMING MORE CONDITIONAL IN THAT
   DIRECTION.
   
   ..EDWARDS.. 05/29/2009
   
   
   ATTN...WFO...CRP...EWX...
   
   LAT...LON   29360003 29739946 29879893 29779851 29399827 29049820
               28599842 28379919 28749955 29360003