MESOSCALE PRECIPITATION DISCUSSION 0457...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1013 PM EDT SUN JUL 09 2017

CORRECTED FOR UPDATED GRAPHIC

AREAS AFFECTED...SOUTHEAST TX

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 100210Z - 100530Z

SUMMARY...VERY HEAVY RAINFALL IS EXPECTED OVER THE NEXT COUPLE
HOURS ACROSS THE HOUSTON METROPOLITAN AREA DUE TO SLOW-MOVING
THUNDERSTORMS. ADJACENT AREAS OF THE MIDDLE AND UPPER TX COASTS
WILL ALSO BE IMPACTED. FLASH FLOODING IS LIKELY.

DISCUSSION...A CLUSTER OF THUNDERSTORMS WITH INTENSE RAINFALL
RATES BETWEEN 2 AND 4 INCHES/HR BASED ON DUAL-POL RADAR AND
SURFACE OBSERVATIONS IS GRADUALLY SETTLING SOUTHEAST INTO THE
HOUSTON METROPOLITAN AREA AND THE ADJACENT SUBURBS.

THE CONVECTION IS BEING FACILITATED BY PROXIMITY OF A WEAK LOW TO
MID LEVEL VORT CENTER AND INTERACTION WITH A SURFACE TROUGH ACROSS
THE IMMEDIATE SOUTHEAST TX COASTAL PLAIN. MLCAPE VALUES OF 2000 TO
2500 J/KG ARE IN PLACE...ALONG WITH PWATS OF NEAR 2.25
INCHES...WHICH COUPLED WITH THE INTENSE COLD CONVECTIVE TOPS NOTED
IN THE EXPERIMENTAL GOES-16 IR SATELLITE IMAGERY IS FACILITATING
THE EXTREME RAINFALL RATES.

EXPECT RAINFALL TOTALS OF LOCALLY OVER 5 INCHES IN AND AROUND THE
HOUSTON METROPOLITAN AREA AND THE ADJACENT SUBURBS AS THIS
SLOW-MOVING CONVECTIVE COMPLEX CONTINUES TO BUILD SOUTHEAST. THE
ACTIVITY WILL ALSO IMPACT AREAS MORE BROADLY INVOLVING THE MIDDLE
AND UPPER TX COASTS AS IT WILL BE TAKING ADVANTAGE OF A MODERATE
TO STRONGLY UNSTABLE AND VERY MOIST BOUNDARY COLUMN. FLASH
FLOODING IS LIKELY CONSIDERING THE URBANIZED ENVIRONMENT THE HEAVY
RAINFALL WILL BE OCCURRING OVER.

ORRISON

ATTN...WFO...HGX...LCH...

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

LAT...LON   30649440 30509380 29839365 29619420 28839547
            28749600 28939634 29499659 29989618 30369547