Graphic for MPD #0059

MESOSCALE PRECIPITATION DISCUSSION 0059
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
915 PM EST SUN FEB 19 2017

AREAS AFFECTED...CENTRAL AND SOUTH TEXAS

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

VALID 200215Z - 200615Z

SUMMARY...STRONG THUNDERSTORMS ORGANIZING OVER PARTS OF CENTRAL
AND SOUTHERN TX AND THE RIO GRANDE VALLEY. HEAVY RAINS WILL RESULT
IN SOME FLASH FLOODING POTENTIAL.

DISCUSSION...AN EXPANDING N/S AREA OF ORGANIZED THUNDERSTORMS WITH
HEAVY RAINFALL RATES UPWARDS OF 2 INCHES/HR EXTENDS FROM CENTRAL
TX SOUTH DOWN TO THE RIO GRANDE RIVER AND INTO NORTHERN MEXICO.
THE BAND OF THUNDERSTORMS IS FORMING ALONG AND JUST AHEAD OF A
COLD FRONT AND WITHIN AN AREA OF QUITE DIFFLUENT FLOW ALOFT
ASSOCIATED WITH A 90+KT 250 MB JET LIFTING NORTH AROUND THE EAST
SIDE OF A STRONG UPPER VORT CENTER OVER NORTHERN MEXICO.

THE AIRMASS AHEAD OF THE BAND OF CONVECTION IS MODERATELY UNSTABLE
WITH MLCAPE VALUES OF 1500 TO 2500 J/KG. MEANWHILE...PWATS OF 1.2
TO 1.4 INCHES ARE NOTED WITH A DEEP SOUTHERLY FETCH OF MOISTURE
TRANSPORT NOTED AHEAD OF THE EJECTING UPPER TROUGH THAT EXTENDS
OVER THE SOUTHERN PLAINS AND INTO NORTHERN MEXICO.

THE HIRES MODEL GUIDANCE IS NOT HANDLING THE CONVECTIVE EVOLUTION
NEAR THE RIO GRANDE WELL...AS CONVECTION IS MUCH MORE ORGANIZED
THAN WHAT WAS FORECAST. THE LATEST IR SATELLITE IMAGERY SHOWS
COOLING CLOUDS WITH EMBEDDED OVERSHOOTING TOPS...ESPECIALLY IN
VICINITY OF KINNEY...MAVERICK...ZAVALA AND DIMMIT COUNTIES. ALSO
STRONG OVERSHOOTING TOPS ARE MOVING INTO WEBB COUNTY JUST OVER THE
RIO GRANDE RIVER.

THE CONVECTION SHOULD REMAIN ORGANIZED GIVEN THE LEVEL OF
INSTABILITY AND MOISTURE POOLED OVER SOUTH TX...WITH THE ACTIVITY
GRADUALLY BOWING OFF TO THE EAST OVER THE NEXT SEVERAL HOURS AS
THE UPPER TROUGH AXIS TO THE WEST GRADUALLY ADVANCES EAST.

EXPECT RAINFALL AMOUNTS OF 2 TO 4 INCHES TO BE POSSIBLE OVER JUST
A COUPLE OF HOURS...WHICH MAY RESULT IN SOME RUNOFF PROBLEMS AND
POSSIBLE FLASH FLOODING.

ORRISON

ATTN...WFO...BRO...CRP...EWX...FWD...SJT...

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

LAT...LON   32089784 30939715 29589757 28329779 27209796
            26689810 26419840 26349874 26459908 26779945
            27309986 28120027 29070026 30089994 31239947
            31589922 31619889 31739820


Last Updated: 918 PM EST SUN FEB 19 2017