MESOSCALE PRECIPITATION DISCUSSION 0342
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1027 PM EDT WED JUN 20 2018

AREAS AFFECTED...EASTERN TX...WEST-CENTRAL TO SOUTHWEST LA

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

VALID 210225Z - 210700Z

SUMMARY...HEAVY RAINFALL ALONG WITH SOME POTENTIAL FOR FLASH
FLOODING WILL REMAIN IN PLACE OVER THE NEXT FEW HOURS.

DISCUSSION...THE LATEST RADAR IMAGERY INDICATES AN MCV GRADUALLY
LIFTING NORTHEAST ACROSS SOUTHEAST TX WHICH CONTINUES TO FOSTER A
N/S AXIS OF HEAVY SHOWERS AND THUNDERSTORMS FROM NEAR THE FAR
UPPER TX COAST NORTH UP ALONG THE TX/LA BORDER. THE LATEST GOES-16
10.3 MICRON/IR IMAGERY STILL SHOWS A SUBSTANTIAL AREA OF VERY COLD
CONVECTIVE TOPS EAST OF THE MCV WITH THIS ACTIVITY WHICH SUGGESTS
THERE IS STILL A FAIR DEGREE OF FORCING IN PLACE.

MOST OF THE CONVECTION IS ALIGNED WITH VERY MOIST AND CONVERGENT
LOW LEVEL FLOW ALONG WITH THE NOSE OF A MODERATELY UNSTABLE
AIRMASS WITH A NOSE OF 1500 TO 2000 J/KG OF MLCAPE.

THE EXPECTATION OVERNIGHT IS FOR THE OVERALL CONVECTIVE
ORGANIZATION TO BEGIN TO WANE AS THE MCV BEGINS TO PULL AWAY AND
WEAKEN...BUT THERE WILL REMAIN AN AXIS OF FAVORABLE LOW LEVEL
CONVERGENCE AND MOISTURE/INSTABILITY TRANSPORT FOR AT LEAST A
SCATTERED AXIS OF CONVECTION.

GIVEN SUCH HIGH PWATS THAT ARE AROUND 2.25 INCHES...THE RAINFALL
RATES WILL REMAIN QUITE HIGH AND WILL LIKELY BE IN EXCESS OF 2.5
INCHES/HR WITHIN THE STRONGER CONVECTIVE CORES. THE LATEST HRRR
GUIDANCE APPEARS TOO SLOW IN ADVANCING THE CURRENT CONVECTIVE AXIS
OFF TO THE NORTH-NORTHEAST...BUT IT DOES FAVOR AS MUCH AS
ADDITIONAL 3 TO 4 INCHES GOING PAST 06Z WHICH SEEMS REASONABLE.

GIVEN THE WET ANTECEDENT CONDITIONS...THESE ADDITIONAL TOTALS MAY
RESULT IN SOME FLASH FLOODING OVERNIGHT.

ORRISON

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

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

LAT...LON   31829370 31559308 30549300 29979310 29499340
            29329408 29599440 29969447 30609429 31399410