MESOSCALE PRECIPITATION DISCUSSION 0134
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
347 AM EDT THU APR 21 2016
 
AREAS AFFECTED...SERN TEXAS / FAR SWRN LOUISIANA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 210746Z - 211345Z
 
SUMMARY...SLOW-MOVING THUNDERSTORMS WITH RAINFALL RATES OF 1-2
IN/HR ARE EXPECTED TO IMPACT PORTIONS OF SERN TEXAS THROUGH 14Z.
GIVEN HEAVY RAINFALL OVER THE PAST FEW DAYS IN THIS AREA...FLASH
FLOODING WILL BE POSSIBLE. 

DISCUSSION...07Z MESOANALYSIS SHOWED A REMNANT OUTFLOW BOUNDARY
FROM DAYTIME CONVECTION ON WEDNESDAY LOCATED ALONG THE SWRN
LOUISIANA COAST...WWD INTO JEFFERSON...CHAMBERS AND SRN HARRIS
COUNTIES IN SERN TEXAS. THE BOUNDARY SEPARATES MORE STABLE AIR TO
ITS NORTH FROM 1000-2000 J/KG ESTIMATED MUCAPE TO ITS SOUTH. WHILE
THE FOCUS FOR SLOW MOVING THUNDERSTORMS WITH HEAVY RAIN HAS BEEN
IN FAR SWRN LOUISIANA OVER THE PAST SEVERAL HOURS...KHGX RADAR AND
GOES-14 SRSO IR IMAGERY HAVE SHOWN A FEW SHOWERS DEVELOPING
FARTHER TO THE WEST OVER SERN TEXAS AND JUST OFFSHORE INTO THE NRN
GULF OF MEXICO.  

AS AN MCS LOCATED OVER NWRN TEXAS LIKELY CONTINUES TO TRACK SEWD
ALONG THE INSTABILITY GRADIENT...LOCAL ENHANCEMENT TO THE LOW
LEVEL FLOW AND LIFT OUT AHEAD OF AN OUTFLOW BOUNDARY ASSOCIATED
WITH THE CONVECTIVE SYSTEM IS EXPECTED TO HELP OVERRUNNING OF THE
OUTFLOW BOUNDARY LOCATED IN FAR SWRN TEXAS. COVERAGE OF CONVECTION
IS NOT EXPECTED TO BE WIDESPREAD BUT SIMILAR TO THE SWRN LOUISIANA
ACTIVITY...STORM MOTIONS WITH ANY CELLS THAT FORM OVER SRRN TEXAS
ARE EXPECTED TO BE SLOW...10 KTS OR LESS...WITHIN A MOIST
ENVIRONMENT CAPABLE OF RAINFALL RATES OF 1-2 IN/HR. GIVEN HEAVY
RAIN WHICH HAS FALLEN OVER SERN TEXAS OVER THE PAST SEVERAL
DAYS...FLASH FLOODING WILL BE POSSIBLE. HI-RES MODELS HAVE BEEN
STRUGGLING WITH THE HANDLING OF THE MCS OVER NWRN TEXAS AND WITH
THUNDERSTORM DEVELOPMENT ALONG THE UPPER TEXAS COAST...SO
CONFIDENCE IN FLASH FLOODING IS ONLY LOW TO MEDIUM.

OTTO

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

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

LAT...LON   30569470 30509305 29739296 29429443 28769573 
            29469615 30209588