MESOSCALE PRECIPITATION DISCUSSION 0346
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
104 PM EDT SAT SEP 06 2014
 
AREAS AFFECTED...WESTERN TX 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 061703Z - 062303Z
 
SUMMARY...THUNDERSTORMS WITH HEAVY RAINFALL ACROSS WESTERN TX ARE
EXPECTED TO SPREAD SOUTHWESTWARD AND EXPAND IN COVERAGE OVER THE
NEXT SEVERAL HOURS.  WITH HOURLY RAIN RATES UP TO 2" ANTICIPATED,
FLASH FLOODING IS POSSIBLE.

DISCUSSION...MORNING THUNDERSTORM ACTIVITY HAS BEEN CONCENTRATED
NEAR AND NORTH OF A FRONTAL BOUNDARY DROPPING SLOWLY SOUTHWARD
ACROSS WESTERN TX DUE TO MODEST SOUTHEASTERLY LOW-LEVEL INFLOW
(15-20 KTS).  MIXED LAYER CAPE VALUES HAVE BUILT TO 500-1000 J/KG
ACROSS WESTERN TX SOUTH OF THE ONGOING THUNDERSTORMS. 
PRECIPITABLE WATER VALUES OF ~1.75" EXIST ACROSS THE REGION, NEAR
THE 99TH PERCENTILE FOR EARLY SEPTEMBER.

THE EXPECTATION IS THAT CAPE VALUES SHOULD CONTINUE TO BUILD OVER
THE NEXT SEVERAL HOURS AS CLOUDINESS CONTINUES TO ERODE ACROSS
WESTERN TX.  AS THE 850 HPA FLOW BECOMES MORE EASTERLY AND
ACCELERATES TO 25-30 KTS BEHIND THE SLOWLY PROGRESSIVE COLD FRONT,
THUNDERSTORMS TO THE WEST-SOUTHWEST OF MIDLAND TX WILL EITHER
CONTINUE TO PROPAGATE WESTWARD TOWARDS THE TOPOGRAPHY OR NEW
CONVECTION WOULD FORM ON WINDWARD SLOPES.  BOTH SETS OF CORFIDI
VECTORS ARE QUITE LIGHT, IMPLYING SLOW CELL MOTIONS SHOULD BE THE
RULE.  AVAILABLE MOISTURE SHOULD ALLOW FOR HOURLY RAIN RATES UP TO
2", WITH LOCAL AMOUNTS OF 2-4" ADVERTISED ACROSS THE REGION IN THE
MOST RECENT MESOSCALE GUIDANCE.  CONSIDERING THE TOPOGRAPHY AND
RELATIVELY LOW FLASH FLOOD GUIDANCE IN THE MOUNTAINS OF WEST TX,
FLASH FLOODING IS CONSIDERED POSSIBLE.

ROTH

ATTN...WFO...EPZ...MAF...SJT...

ATTN...RFC...WGRFC...

LAT...LON   32610398 32560321 32100264 31340212 30620263 
            30480279 29870340 29360410 30170471 31000447 
            31280466 31460478 31980496 32270480 32540431