MESOSCALE PRECIPITATION DISCUSSION 0395
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
710 PM EDT TUE JUL 03 2018

AREAS AFFECTED...SOUTHWEST LOUISIANA AND FAR EAST TEXAS

CONCERNING...HEAVY RAINFALL

VALID 032309Z - 040500Z

SUMMARY...NUMEROUS SHOWERS AND THUNDERSTORMS WILL CONTINUE THIS
EVENING ACROSS ACROSS LOUISIANA AND PARTS OF SOUTHEAST TEXAS IN A
VERY MOIST ENVIRONMENT. THE AREAS OF HEAVY RAIN MAY BE SLOW-MOVING
WHICH SHOULD CONTRIBUTE TO THE POSSIBILITY OF FLASH FLOODING. RAIN
RATES OF 2 TO 3 IN/HR AND 6-HOUR RAINFALL TOTALS MAY EXCEED 5
INCHES ON A LOCALIZED BASIS IN THE OUTLINED AREA.

DISCUSSION...A WEAK SURFACE LOW WAS EVIDENT IN SURFACE
OBSERVATIONS OVER EASTERN LOUISIANA THAT WAS GRADUALLY DRIFTING TO
THE WEST.  MANY OF THE 12Z MODELS AND HI RESOLUTION GUIDANCE
MODELS SHOW THIS GENERAL MOTION TO CONTINUE INTO THE EVENING. 
RADAR VWPS AND GOES-16 DERIVED MOTION WINDS CONTINUED TO INDICATE
BROADLY CONFLUENT BOUNDARY LAYER FLOW OVER EAST TEXAS AND FAR
WESTERN LOUISIANA...GENERALLY TO THE NORTHWEST AND WEST OF THE
SURFACE LOW WITH RADAR IMAGERY SHOWING TWO LINES OF CONVECTION IN
THE SAME AREA.

AS THE LOW CONTINUES TO RETROGRADE TO THE WEST...MODELS ARE IN
EXCELLENT AGREEMENT IN SHOWING WIDESPREAD CONVECTIVE DEVELOPMENT
IN THE BUBBLE OF HIGH PWS ACROSS THE REGION. CIRA BLENDED TPWS ARE
AROUND 2.0 TO 2.5 INCHES AND MANY OF THE GPS OBSERVATIONS IN THE
AREA ARE BETWEEN 2.2 AND 2.4 INCHES. THIS IS CONSISTENT WITH DEEP
TROPICAL MOISTURE...AND SHOULD SUPPORT VERY HEAVY RAIN RATES. THE
CONVECTION HAS BEGUN TO SHOW STEADY MOVEMENT OVER EAST TX WHICH
MAY MITIGATE SOME OF THE POTENTIAL FOR FLASH FLOODING BUT THAT
DOES NOT APPEAR ENOUGH TO COMPLETELY OFFSET SOME OF THE HIGHEST
RAINFALL RATES.

AREAS NEAR THE LOW-LEVEL CIRCULATION CENTER HAVE RECENTLY RECEIVED
HEAVY RAINFALL.  THIS INCREASES THE RISK OF ADDITIONAL FLASH
FLOODING EVEN THOUGH INSTABILITY LOOKS TO BE DIMINISHED.  FARTHER
WEST...IN A REGION OF BETTER INSTABILITY DUE IN PART TO BREAKS IN
THE CLOUD COVER...RECENT HRRR FORECASTS SHOW RAINFALL RATES OF 2
TO 3 INCES PER HOUR IN LOCALIZED AREAS.

THEREFORE...CHANCES OF LOCALIZED HEAVY RAINFALL AND FLASH FLOODING
APPEAR HIGHEST IN SOUTHEAST TEXAS NEAR A LINE OF STORMS THAT WERE
PRODUCING HEAVY RAINFALL...BUT HEAVY TO EXCESSIVE RAINFALL WILL BE
POSSIBLE ANYWHERE IN ADJACENT PORTIONS OF LOUISIANA OR EXTREME
EAST TEXAS.

BANN

ATTN...WFO...FWD...HGX...JAN...LCH...LIX...LZK...OUN...SHV...
TSA...

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

LAT...LON   35649444 33119353 31889197 30739140 30089066
            29429067 29189394 30449565 34869594