MESOSCALE PRECIPITATION DISCUSSION 0383
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1037 PM EDT WED SEP 17 2014
 
AREAS AFFECTED......CENTRAL AND SOUTHEAST TX... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 180235Z - 180735Z
 
SUMMARY...A DEVELOPING LOW LEVEL INFLOW WILL FEED HIGH MOISTURE
CONTENT AIR TO CONVECTION ACROSS CENTRAL AND SOUTHEAST TX. AS THE
LOW LEVEL INFLOW OPPOSES A SLOW SOUTHEAST CELL MOVEMENT...FLASH
FLOODING IS POSSIBLE.

DISCUSSION...SCATTERED CONVECTION HAS DEVELOPED ACROSS PORTIONS OF
CENTRAL AND SOUTHEAST TX...AS A DEVELOPING LOW LEVEL FLOW FEEDS
PRECIPITABLE WATER VALUES AS HIGH AS 2.30 INCHES (WHICH IS ABOUT
TWO STANDARD DEVIATIONS ABOVE NORMAL) INTO THE REGION. 
THE INCREASING LOW LEVEL FLOW WILL OPPOSE WEAK CORFIDI VECTOR
(WHICH WILL AVERAGE LESS THAN 10 KNOTS)...LEADING TO THE POTENTIAL
FOR SLOW MOVING OR EVEN BACK BUILDING CELLS.

THE HIGH PRECIPITABLE WATER VALUES COULD LEAD TO RAINFALL RATES AS
HIGH AS 2 INCHES AN HOUR (WHICH HAS ALREADY BEEN ESTIMATED BY THE
KHGX RADAR). THE LATEST HIGH RESOLUTION MODEL OUTPUT (INCLUDING
THE 23Z HRRR AND 18Z NAM CONEST) SUGGEST THAT LOCAL 2 TO 4 INCH
RAINFALL AMOUNTS ARE POSSIBLE. THREE HOUR FLASH FLOOD GUIDANCE
VALUES ARE FAIRLY HIGH...BUT THE HIGH RAINFALL RATES AND SLOW CELL
MOVEMENT COULD RESULT IN FLASH FLOODING.

THE HIGHEST CONFIDENCE FOR FLASH FLOODING IS THROUGH ABOUT 05Z.
AFTER THAT TIME...THE INSTABILITY WANES...AND THE SSEO
NEIGHBORHOOD PROBABILITIES DROP OFF SIGNIFICANTLY.

HAYES

ATTN...WFO...CRP...EWX...FWD...HGX...SJT...

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

LAT...LON   31609849 31599830 31559812 31489784 31409767 
            31309746 31269741 31069690 30889646 30799624 
            30769608 30679594 30459566 30209543 30029535 
            29849537 29649541 29529544 29239557 29079588 
            28959621 28929642 28949647 28949705 29119743 
            29519793 29929841 30449882 30739892 31049903 
            31259904 31399900 31519881 31579865