MESOSCALE PRECIPITATION DISCUSSION 0754
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
500 PM EDT MON AUG 28 2017

AREAS AFFECTED...UPPER TX COAST

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

VALID 282100Z - 290130Z

SUMMARY...ADDITIONAL RAINFALL AMOUNTS OF 3.00 TO 6.00 INCHES OVER
PORTIONS OF THE UPPER TX COAST WILL EXACERBATE ONGOING FLOODING
CONCERNS INTO THE EVENING HOURS.

DISCUSSION...THE GOES-16 CLEAN IR LOOP SHOWED COOLING TOPS NORTH
OF THE CENTER OF HARVEY...IN THE AXIS OF BEST MID LEVEL
DEFORMATION. WHILE THE RADAR PRESENTATION IS NOT AS DISTINCT WITH
THE CONVECTION OCCURRING ALONG THE DEFORMATION ZONE...2.50 INCH
PRECIPITABLE WATER AIR IN THE COLUMN SUGGESTS THAT WARM RAIN
PROCESSES ARE DOMINANT.

HOURLY RAINFALL RATES ARE GENERALLY NEAR AN INCH WITH THE LOWER
TOPPED CONVECTION (BASED ON THE HGX RADAR)...THOUGH LOCALLY HIGHER
AMOUNTS ARE POSSIBLE WHERE THE INSTABILITY BECOMES MORE SURFACE
BASED. THIS IS MOST LIKELY OVER JEFFERSON COUNTY TX...WHERE HOURLY
RAINFALL RATES COULD PEAK NEAR 2.00 INCHES. 

THE DEFORMATION ZONE IS EXPECTED TO DROP SLOWLY SOUTH DURING INTO
THE EVENING HOURS. EVEN RELATIVELY MODEST HOURLY RAINFALL RATES
NEAR AN INCH OR SO COULD RESULT IN AN 3.00 TO 6.00 INCHES OF
ADDITIONAL RAINFALL THROUGH 01Z...WITH THE HIGHEST AMOUNTS
POSSIBLY AFFECTING THE NORTHERN HOUSTON METRO AREA. THESE AMOUNTS
ARE SUPPORTED BY THE MOST RECENT HRRR...AS WELL AS THE 12Z WRF
ARW.

THE ADDITIONAL RAINFALL WILL EXACERBATE ONGOING FLOODING...OR
PRODUCE NEW FLOODING OVER SATURATED SOILS INTO THE EVENING HOURS.

HAYES

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

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

LAT...LON   30699373 30619332 30239318 29609384 29389415
            28869552 28719594 28969658 29489658 29959611
            30459483