MESOSCALE PRECIPITATION DISCUSSION 0011
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
224 AM EDT MON MAR 09 2015
 
AREAS AFFECTED...SOUTH TO SOUTHEASTERN TX... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 090624Z - 091124Z
 
SUMMARY...PRECIPITATION MOVING ACROSS THE LOWER RIO GRANDE IS
BECOMING INCREASINGLY BETTER ORGANIZED. EXPECT SEVERAL HOURS OF
MODERATE TO HEAVY RAINFALL WHICH MAY SUPPORT LOCALIZED FLASH
FLOODING OVER THE AFFECTED REGION.

DISCUSSION...A VERY FAVORABLE PATTERN FOR HEAVY RAINFALL IS IN
PLACE ACROSS SOUTH TO SOUTHEASTERN TX. A SHORTWAVE TROF CURRENTLY
MOVING THROUGH WEST-CENTRAL MEXICO IS ACCOMPANIED BY AN IMPRESSIVE
SLUG OF TROPOSPHERIC MOISTURE PER THE BLENDED-TPW PRODUCT. GPS
PROFILER DATA SUGGESTS PWATS IN THE 1.50 TO 1.75 INCH RANGE ALONG
THE WESTERN GULF COAST . THE 04Z RAP SHOWS PERSISTENT
SOUTH-SOUTHWESTERLY FLOW CONTINUING TO MAINTAIN A HEALTHY AXIS OF
MOISTURE ACROSS AN AREA CHARACTERIZED BY BROAD UPPER DIFFLUENCE. 

THE LIMITING FACTOR HERE IS INSTABILITY WITH MUCAPE VALUES OF 500
J/KG AND GREATER CONFINED TO THE WARM SECTOR IN THE WESTERN GULF
OF MEXICO. ISENTROPIC LIFT ACROSS THE WESTERN GULF COAST CONTINUES
TO SPAWN OVERRUNNING RAINFALL WITH CURRENT HOURLY RATES OF ONLY A
QUARTER TO ONE-THIRD OF AN INCH. EXPECT THESE TOTALS TO COME UP AS
THE BETTER FORCING MOVES ACROSS THE MEXICO/TEXAS BORDER. THE
FORECAST CELL MOTIONS SHOULD CONTINUE TO CARRY THE PRECIPITATION
FROM SOUTHWEST TO NORTHEAST DURING THE NEXT SEVERAL HOURS. REPEAT
CONVECTION EMERGING FROM SOUTH TX WILL BE THE MAIN CULPRIT FOR THE
THREAT FOR FLASH FLOODING. WHILE FFG VALUES ARE ON THE HIGHER
SIDE...ISOLATED REPORTS OF FLASH FLOODING WILL BE
POSSIBLE...ESPECIALLY CLOSER TO THE TX HILL COUNTRY.

THERE IS RATHER HIGH CONFIDENCE IN HEAVY RAINFALL SPREADING FROM
SOUTHERN TO SOUTHEASTERN TX GIVEN THE CONSENSUS IN THE
HIGH-RESOLUTION GUIDANCE. THE 00Z SPC-WRF/NSSL-WRF/NAM-CONEST
ALIGN QUITE WELL WITH 2 TO 3 INCHES AMOUNTS DURING THE NEXT 6
HOURS. 


RUBIN-OSTER

ATTN...WFO...BRO...CRP...EWX...FWD...HGX...LCH...SHV...

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

LAT...LON   32229467 32189388 31279369 30219445 29469561 
            28829645 27969695 26899734 26489807 26489883 
            27129932 28439847 29439813 30099761 30719647 
            31399539