MESOSCALE DISCUSSION 0933
   NWS STORM PREDICTION CENTER NORMAN OK
   0234 AM CDT WED JUN 03 2009
   
   AREAS AFFECTED...PORTIONS SRN OK AND N TX.
   
   CONCERNING...HEAVY RAINFALL 
   
   VALID 030734Z - 031000Z
   
   SLOW MOVING COMPLEX OF STG TSTMS IS FCST TO UNDERGO NET SEWD DRIFT
   ACROSS SRN OK AND NW TX -- COVERING MORE OF RED RIVER REGION BETWEEN
   SPS....LAKE TEXOMA AND DUA DURING NEXT SEVERAL HOURS.  PRIMARY
   THREAT OF HEAVY RAINFALL IS EXPECTED TO CONTINUE WITH THIS
   ACTIVITY...WITH MERGING AND TRAINING CORES OF 1-2 INCH/HOUR RATES
   WILL BE COMMON...LOCALLY/BRIEFLY 2.5-3 INCH/HOUR. 
   ADDITIONAL/ISOLATED SVR GUSTS ALSO ARE POSSIBLE.
   
   NARROW WEDGE OF RICHLY MOIST BOUNDARY LAYER AIR ADVECTED NWD INTO N
   TX AND RED RIVER REGION YESTERDAY...AS EVIDENT IN LATE AFTERNOON VIS
   IMAGERY THAT SHOWED PLUME OF DEEP CU.  THIS AIR MASS CONTAINS SFC
   DEW POINTS UPPER 60S TO 70 F...AS WELL AS PW AROUND 1.5 INCH PER GPS
   AND 00Z FWD RAOB.  7Z SFC MESOANALYSIS INDICATES OUTFLOW BOUNDARY
   FROM CENTRAL TX MCS FROM CLAY COUNTY ACROSS
   COOKE/COLLIN/KAUFMAN/NAVARRO COUNTIES THEN SSWWD INTO S-CENTRAL TX. 
   THIS BOUNDARY WILL CONTINUE MOVING NEWD/EWD OVER N-CENTRAL
   TX...ENGAGING IN W-E MERGER WITH CONVERGENCE ZONE ASSOCIATED WITH
   SRN OK ACTIVITY AND NARROWING/CUTTING OFF SUPPLY OF OPTIMALLY
   MOIST/UNSTABLE INFLOW FROM W-E.  THIS PROCESS WILL REFOCUS HEAVY
   RAIN AND MRGL SVR THREAT EWD WITH TIME.  DEEP-LAYER VERTICAL WIND
   PROFILES AND SHEAR EACH WILL REMAIN WEAK...LEAVING PROPAGATION INTO
   LOW LEVEL MOISTURE/THETAE AXIS NEAR RED RIVER AS PRIMARY FOCUS FOR
   CONVECTIVE MOTION.
   
   INTERMITTENT...MARGINAL SVR POTENTIAL ALSO EXISTS ACROSS THIS REGION
   IN FORM OF WET MICROBURSTS AND SMALL BOW SEGMENTS.  OK MESONET
   SAMPLED ONE SUCH DOWNBURST WITH 50 KT GUST OCCURRED AT 120Z IN
   COTTON COUNTY OK.  ALTHOUGH PRECONVECTIVE BOUNDARY LAYER IN RED
   RIVER REGION IS VERY MOIST -- WITH LITTLE EVAPORATIONAL
   COOLING/ACCELERATION ENHANCEMENT EXPECTED IN SUBCLOUD REGION -- SLOW
   RATE OF DIABATIC COOLING WILL MEAN ONLY GRADUAL INCREASE IN SFC
   STATIC STABILITY TO INHIBIT ANY STG-SVR DOWNDRAFTS GENERATED ALOFT.
   
   ..EDWARDS.. 06/03/2009
   
   
   ATTN...WFO...TSA...FWD...OUN...
   
   LAT...LON   33849845 34319837 34529753 34709581 34509513 33969528
               33699572 33599676 33749806 33849845