MESOSCALE PRECIPITATION DISCUSSION 0333
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
331 AM EDT WED JUN 20 2018

AREAS AFFECTED...SOUTH-CENTRAL TX

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

VALID 200730Z - 201330Z

SUMMARY...ADDITIONAL HEAVY RAINFALL IS EXPECTED THIS MORNING WITH
MORE FLASH FLOODING LIKELY.

DISCUSSION...THE LATEST 1-MINUTE GOES-16 CLEAN IR IMAGERY SHOWS
SOME IMPRESSIVELY COLD CONVECTIVE TOPS OVER PORTIONS OF
SOUTH-CENTRAL TO FAR SOUTH TX AND ALSO FOCUSED ALONG AND JUST
OFFSHORE OF THE GULF COAST. RADAR CONFIRMS HEAVY RAINFALL WITH
MOST OF THE ACTIVITY CURRENTLY SOUTH AND EAST OF THE GREATER
CORPUS CHRISTIE AREA WHICH LOCALLY SAW VERY HEAVY RAINFALL TOTALS
LAST EVENING.

THE HEAVY SHOWER AND THUNDERSTORM ACTIVITY HAS BEEN ATTEMPTING TO
BECOME A BIT BETTER ORGANIZED AGAIN AROUND THE EASTERN FLANK OF
THE PERSISTENT MID LEVEL LOW CENTER OVER SOUTH TX. THE CONVECTION
HAS BEEN DEVELOPING ALONG A VERY FAVORABLE AXIS OF LOW LEVEL
MOISTURE CONVERGENCE AND WITH PROXIMITY OF A NOSE OF 1000 TO 1500
J/KG OF MLCAPE JUST OFFSHORE.

THE PWATS ACROSS THE REGION AGAIN ARE VERY HIGH AND INDICATIVE OF
A DEEP TROPICAL COLUMN WITH VALUES AS HIGH AS 2.5 INCHES. HIGHLY
CONCENTRATED MOISTURE IS SEEN IN THE 500/300 MB LAYER AS PER
CIRA-LPW DATA...AND THIS WILL FAVOR HIGHLY EFFICIENT RAINFALL
PROCESSES FOR ENHANCED RAINFALL RATES THAT COULD EXCEED 3
INCHES/HR. THE DEEP CONVECTIVE ORGANIZATION WITH OCCASIONAL
OVERSHOOTING TOPS WILL FURTHER ENCOURAGE EXTREMELY HEAVY RAINFALL
RATE POTENTIAL.

THE LATEST RAP FORECASTS THE MID LEVEL LOW CENTER TO MOVE VERY
LITTLE THROUGH MID MORNING WHICH WILL ALLOW MULTIPLE CYCLONIC
CONVECTIVE BANDS TO TEND TO FOCUS OVER THE SAME AREA.
CONSEQUENTLY...VERY HEAVY RAINFALL TOTALS ARE EXPECTED. IN
FACT...THE LATEST HIRES GUIDANCE LED BY THE HRRR AND HRRRX SUGGEST
AS MUCH AS AN ADDITIONAL 4 TO 6+ INCHES OF RAIN AT LEAST
LOCALLY...WITH THE MAIN THREAT FOCUSED AROUND THE SOUTHERN AND
EASTERN FLANKS OF THE CIRCULATION CENTER.

THESE ADDITIONAL RAINS WILL CAUSE FLASH FLOODING AND SOME OF IT
MAY BE SIGNIFICANT GIVEN THE EARLIER HEAVY RAINFALL.

ORRISON

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

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

LAT...LON   29719697 29339644 28729628 28289649 27929685
            27349725 26519714 25869705 25819754 25909770
            25969801 26019838 26169863 26339913 26619941
            26869951 27199962 27589964 27939956 28349933
            28889897 29309849 29669789