Graphic for MPD #0410

MESOSCALE PRECIPITATION DISCUSSION 0410
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
406 PM EDT THU JUN 29 2017

AREAS AFFECTED...SOUTHEAST TEXAS AND SOUTHERN LOUISIANA

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

VALID 292005Z - 300005Z

SUMMARY...ADDITIONAL ROUNDS OF HEAVY THUNDERSTORMS OVER SATURATED
GROUNDS COULD LEAD TO LOCALIZED FLASH FLOODING ISSUES.  HOURLY
RAINFALL RATES OF 2 INCHES PER HOUR OR MORE ARE POSSIBLE WITH THE
STRONGEST CONVECTION.

DISCUSSION...THE LATEST DOPPLER RADAR INDICATES NUMEROUS
THUNDERSTORMS ONGOING ACROSS EXTREME SOUTHEAST TEXAS AND INTO THE
SOUTHERN HALF OF LOUISIANA THIS AFTERNOON.  THIS IS IN CONJUNCTION
WITH A WEAK 500MB VORTMAX OVER LOUISIANA THAT IS ADVECTING DEEP
MOISTURE NORTHWARD FROM THE GULF OF MEXICO.  PWS ARE ANOMALOUSLY
HIGH WITH VALUES INTO THE 2.25 TO 2.5 RANGE PER THE SPC ANALYSIS
AND RAP MODEL, AND THIS IS CONFIRMED BY THE 12Z LIX SOUNDING. 
850MB SOUTHWESTERLY INFLOW ON THE ORDER OF 30 TO 40 KNOTS IS
ADVECTING MLCAPE OF ROUGHLY 1500 TO 2000 J/KG INTO THIS REGION,
ALLOWING FOR ADDITIONAL ROUNDS OF CONVECTION TO DEVELOP.

RECENT HIGH RES GUIDANCE IS INDICATING THE POTENTIAL FOR 1 TO 3
INCHES OF RAINFALL FOR PARTS OF THIS REGION, WITH SOME ISOLATED 4
INCH AMOUNTS POSSIBLE.  THIS IS SUPPORTED BY BOTH THE HRRR AND ITS
EXPERIMENTAL VERSION.  THE GREATEST CONCERNS FOR FLASH FLOODING
WOULD BE OVER THOSE AREAS THAT HAVE RECEIVED EXCESSIVE RAINFALL
OVER THE PAST 24 HOURS.  MODEL DATA SUGGEST THAT THIS CONVECTION
WILL WANE AFTER 00Z WITH THE LOSS OF DAYTIME HEATING.

HAMRICK

ATTN...WFO...HGX...JAN...LCH...LIX...

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

LAT...LON   30999156 30879065 30488985 30248978 29848955
            29318897 28858915 28998986 28929085 29329169
            29519247 29619331 29569385 29429424 29329456
            29599478 30069472 30519439 30849367 30979271
           


Last Updated: 406 PM EDT THU JUN 29 2017