MESOSCALE PRECIPITATION DISCUSSION 0073
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
103 PM EST FRI MAR 10 2017

AREAS AFFECTED...SOUTH-CENTRAL TX...LOWER RIO GRANDE VALLEY

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 101800Z - 110000Z

SUMMARY...HEAVY RAINS FROM THUNDERSTORMS WILL CONTINUE TO IMPACT
PARTS OF SOUTH-CENTRAL TX AND THE LOWER RIO GRANDE VALLEY THROUGH
THIS AFTERNOON. FLASH FLOODING WILL BE POSSIBLE.

DISCUSSION...THE LATEST IR/WV SATELLITE IMAGERY SUGGESTS A WEAK
SHORTWAVE TROUGH OVER THE LOWER RIO GRANDE VALLEY WHICH IS
INTERACTING WITH A BROAD AREA OF MOIST LOW LEVEL EAST TO SOUTHEAST
FLOW COMING IN OFF THE GULF OF MEXICO AND A WEAK INVERTED SURFACE
TROUGH. THIS COUPLED WITH AN UPTICK IN DIURNAL HEATING HAS BEEN
RESULTING IN A GRADUAL WESTWARD EXPANSION OF CONVECTION ACROSS
SOUTH-CENTRAL TX.

ALREADY STRONG CONVECTION HAS PRODUCED HEAVY RAINS AND FLASH
FLOODING IN THE DOWNTOWN CORPUS CHRISTI AREA...AND ADDITIONAL
CONVECTION IS EXPECTED THIS AFTERNOON WITH A GRADUALLY
DESTABILIZING BOUNDARY LAYER THROUGH SOLAR INSOLATION/DIURNAL
HEATING. SOME OF THE GREATER INSTABILITY WITH TIME SHOULD TEND TO
FOCUS FARTHER SOUTH DOWN ACROSS THE LOWER RIO GRANDE VALLEY WHERE
MORE SURFACE HEATING IS EXPECTED...AND THIS WILL LIKELY BE WHERE
THE GREATER CONVECTIVE THREAT SETS UP THROUGH MID TO LATE
AFTERNOON.

GPS-DERIVED PWATS ARE RUNNING BETWEEN 1.6 AND 1.8 INCHES...AND
WILL BE SUPPORTIVE OF RAINFALL RATES APPROACHING 2 INCHES/HR. THE
INTENSE RAINFALL RATES AND RELATIVELY SLOW CELL MOTION WILL FOSTER
LOCALLY AS MUCH AS 3 TO 5 INCHES OF RAIN IN AS LITTLE AS 2 TO 3
HOURS. THIS MAY RESULT IN SOME ADDITIONAL RUNOFF/FLASH FLOODING
CONCERNS THROUGH THE AFTERNOON. WILL CONTINUE TO MONITOR.

ORRISON

ATTN...WFO...BRO...CRP...EWX...HGX...

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

LAT...LON   28889864 28739753 28739657 28339635 27869683
            27139719 26619711 26079705 25809731 25879776
            25979799 26039833 26259871 26419913 26739938
            27129956 27509969 27899990 28399990 28749951