MESOSCALE PRECIPITATION DISCUSSION 0402
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
740 PM EDT MON JUN 26 2017

AREAS AFFECTED...CENTRAL TO SOUTH-CENTRAL TX

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

VALID 262335Z - 270330Z

SUMMARY...SLOW-MOVING SHOWERS AND THUNDERSTORMS WITH INTENSE
RAINFALL RATES WILL LIKELY CAUSE AT LEAST SOME FLASH FLOOD
POTENTIAL OVER THE NEXT FEW HOURS.

DISCUSSION...LATE-DAY EXPERIMENTAL GOES-16 VIS/0.64 MICRON IMAGERY
SHOWS A WELL-DEFINED MCV MOVING GRADUALLY EAST-SOUTHEAST TOWARD
THE TX HILL COUNTRY...AND THIS VORT CENTER IS INTERACTING WITH A
MOIST AND UNSTABLE BOUNDARY LAYER FOR A CLUSTER OF RELATIVELY WELL
ORGANIZED CONVECTION.

THE CONVECTION IS ADVANCING INTO AN AIRMASS CHARACTERIZED BY 1.75
INCH PWATS AND MLCAPE VALUES OF NEAR 1000 J/KG. THE 12Z ARW/NMMB
AND NSSL-WRF GUIDANCE MAY BE DOWNPLAYING THE CONVECTIVE POTENTIAL
TOO MUCH OVER THE TX HILL COUNTRY...AS RECENT RUNS OF THE
HRRR/HRRRX GUIDANCE DO SUGGEST SOME SMALL SCALE ORGANIZATION OVER
THE NEXT FEW HOURS.

THIS WOULD BE SUPPORTED BY THE FACT THAT THE VORT ENERGY IS QUITE
CONCENTRATED AND WILL STILL BE ADVANCING EAST-SOUTHEAST INTO A
MOIST/UNSTABLE ENVIRONMENT WITH AT LEAST MODEST SOUTHEAST LOW
LEVEL INFLOW AND ABOUT 20 TO 30 KTS OF EFFECTIVE BULK SHEAR. SOME
ADDITIONAL CONVECTION MAY ALSO FORM A BIT FARTHER SOUTH AND BECOME
SEMI-ORGANIZED SOUTH OF WHERE THE CURRENT ORGANIZED CLUSTER IS
INVOLVING CONCHO COUNTY.

RAINFALL RATES OF OVER 2 INCHES/HR AND LOCALIZED TOTALS UP TO OVER
4 INCHES WILL BE POSSIBLE. CANNOT RULE OUT SOME RUNOFF PROBLEMS OR
POSSIBLE FLASH FLOODING AS A RESULT. WILL CONTINUE TO MONITOR.

ORRISON

ATTN...WFO...EWX...FWD...SJT...

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

LAT...LON   31629877 31529791 30759740 30069753 29639791
            29239888 29149945 29210010 29330067 29580086
            29620097 30020103 30420072 30759995 31329949