MESOSCALE PRECIPITATION DISCUSSION 0346
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
152 PM EDT THU JUN 21 2018

AREAS AFFECTED...DEEP SOUTH TEXAS

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

VALID 211751Z - 212151Z

SUMMARY...ADDITIONAL CLUSTERS OF HEAVY SHOWERS AND THUNDERSTORMS
WILL MAINTAIN A RENEWED THREAT FOR FLASH FLOODING THIS AFTERNOON
OVER AREAS THAT HAVE RECEIVED EXCESSIVE RAINFALL RECENTLY.

DISCUSSION...AN MCV TO THE WEST OF BROWNSVILLE TEXAS EARLY THIS
AFTERNOON CONTINUES TO REMAIN NEARLY STATIONARY. NUMEROUS HEAVY
SHOWERS AND STRONG THUNDERSTORMS CONTINUE TO DEVELOP TO THE EAST
OF THIS VORTMAX AND JUST INLAND FROM THE COAST.  SUSTAINED DEEP
MOISTURE FLUX FROM THE WESTERN GULF OF MEXICO WITH MLCAPES NEAR
1500 J/KG PER LATEST SPC MESOANALYSIS WILL SUPPORT ROBUST
CONVECTION WITH RAINFALL RATES OF 3+ INCHES PER HOUR AT TIMES.

EXTREMELY HIGH PWS ON THE ORDER OF 2.5 INCHES REMAIN IN PLACE
ACROSS THE REGION WHICH IS INDICATIVE OF A DEEP TROPICAL AIRMASS. 
WARM CLOUD LAYERS ARE QUITE DEEP AND LEADING TO HIGHLY EFFICIENT
COLLISION-COALESCENCE PROCESSES.

TAKING INTO ACCOUNT THE PREVIOUS EXTREME RAINFALL OVER PARTS OF
THE REGION OVER THE PAST 36 HOURS AND SATURATED GROUND, THIS
ADDITIONAL RAINFALL WILL ONLY EXACERBATE ONGOING FLOODING AND
THEREFORE FLASH FLOODING IS LIKELY FOR SOME AREAS.

D. HAMRICK

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

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

LAT...LON   29179701 29159627 28999583 28519589 28179649
            27819694 27319726 26849725 26249710 25919709
            25789744 25899833 26099889 26479936 27179960
            27939933 28469872 28929783