MESOSCALE PRECIPITATION DISCUSSION 0296
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
108 PM EDT SUN JUN 04 2017

AREAS AFFECTED...FAR SOUTHEASTERN TX/SOUTHWESTERN LA...

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

VALID 041706Z - 042021Z

SUMMARY...RAINFALL RATES IN EXCESS OF 2 INCHES PER HOUR SHOULD
CONTINUE WITHIN A DEEP TROPICAL AIR MASS COUPLED WITH PERSISTENT
REGENERATION ALONG THE OFFSHORE FEEDER BANDS. GIVEN INCREASINGLY
SATURATED SOILS FROM THE HEAVY RAINFALL THIS MORNING...FLASH
FLOODING WILL BE POSSIBLE...ESPECIALLY ALONG THE UPPER TX COAST
EXTENDING TO THE TX/LA BORDER.

DISCUSSION...EXPERIMENTAL GOES-16 VISIBLE SATELLITE IMAGERY
DEPICTED THREE INFLOW FEEDER BANDS INTERCEPTING THE UPPER TX
COAST. THE WESTERN MOST BAND HAS BEEN THE MOST ACTIVE WITH MORE
VERTICALLY DEVELOPED CONVECTIVE TOPS AND HAS BEEN A FOCUS FOR
REGENERATION ALONG THE SOUTHWESTERN FLANK OF THE SQUALL LINE. THE
KLCH DUAL-POL RADAR ESTIMATES HAVE SUGGESTED 2 TO 3 INCH HOURLY
AMOUNTS WHICH HAS BEEN CONFIRMED BY A FEW MESONET OBSERVATIONS.
THIS CONVECTIVE COMPLEX ALREADY HAS A HISTORY OF PRODUCING FLASH
FLOOD CONDITIONS WITH A REPORT JUST SOUTHWEST OF BEAUMONT TX A
COUPLE HOURS AGO. GIVEN THE SLOW-MOVING NATURE OF THIS
SYSTEM...PARTICULARLY ALONG THE SOUTHWESTERN EXTENT OF THE
COMPLEX...FLASH FLOODING WILL REMAIN POSSIBLE UNTIL THE SQUALL
LINE BECOMES FORWARD-PROPAGATING.

THE THERMODYNAMIC ENVIRONMENT IN PLACE REMAINS FAVORABLE GIVEN
2000 TO 3000 J/KG OF SURFACE-BASED INSTABILITY ACROSS THE INFLOW
REGION. THIS REMAINS IN THE PRESENCE OF HIGHLY CONFLUENT LOW-LEVEL
FLOW (PER VAD-WIND PROFILE DATA) AND PRECIPITABLE WATER VALUES
NEARING/EXCEEDING 2 INCHES. WHILE NOT EVIDENT SO MUCH IN SATELLITE
IMAGERY...HIGH-RESOLUTION GUIDANCE INDICATES A WEAKENING TREND THE
NEXT FEW HOURS. MEANWHILE...ADDITIONAL DEVELOPMENT IS SUGGESTED
FARTHER UPSTREAM IN ADVANCE OF THE NEXT SHORTWAVE CURRENTLY EAST
OF THE BIG BEND. THIS WOULD ULTIMATELY BRING CONVECTION INTO THE
AFFECTED AREA AGAIN ALTHOUGH NOT CERTAIN HOW INTENSE THIS ACTIVITY
WOULD BE GIVEN HOW MUCH CONVECTIVE OVERTURNING HAS OCCURRED THIS
MORNING/EARLY AFTERNOON.


RUBIN-OSTER

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

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

LAT...LON   31459233 31169204 29929224 29289293 28879372
            28709466 28889520 29419481 30239355 31359279