418
FXUS64 KBRO 301809
AFDBRO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
109 PM CDT WED SEP 30 2026
..NEW DISCUSSION, AVIATION, MARINE, HYDROLOGY
KEY MESSAGES
UPDATED AT 1247 PM CDT WED SEP 30 2026
- WIDESPREAD MAJOR (LEVEL 3 OF 4) TO EXTREME (LEVEL 4 OF 4) HEAT
RISK EXPECTED ACROSS THE REGION THROUGH THURSDAY.
- COOLER AND WETTER CONDITIONS ARE EXPECTED LATE THIS WEEK INTO
EARLY NEXT WEEK DUE TO A FRONTAL PASSAGE AND A MULTI-DAY
RAINFALL EVENT THURSDAY THROUGH THE WEEKEND.
- THE WEATHER PREDICTION CENTER (WPC) HAS DEEP SOUTH TEXAS UNDER
A SLIGHT (LEVEL 2 OF 4) TO MODERATE (LEVEL 3 OF 4) RISK FOR
FLOODING RAINFALL FOR THURSDAY, A MARGINAL (LEVEL 1 OF 4) TO
SLIGHT RISK ON FRIDAY, AND A MARGINAL RISK ALONG THE COAST ON
SATURDAY.
DISCUSSION
ISSUED AT 1247 PM CDT WED SEP 30 2026
THERE REMAINS A MAJOR TO EXTREME RISK OF HEAT-RELATED ILLNESS
TODAY AND THURSDAY AFTERNOON. A SPECIAL WEATHER STATEMENT IS IN
EFFECT AND HEAT ADVISORIES MAY BE NEEDED.
AN UPPER LEVEL TROUGH, SLOW-MOVING SURFACE FRONTAL BOUNDARY, AND
DEEP TROPICAL MOISTURE CONTINUES TO WORK EAST INTO THIS WEEKEND
AND COMBINE WITH HUMID SOUTHEASTERLY FLOW OFF THE GULF TO BRING A
MUCH-NEEDED CHANCE OF BENEFICIAL RAINFALL INTO NEXT WEEK. THE BEST
CHANCE OF PERSISTENT HEAVY RAINFALL THURSDAY INTO SATURDAY
REMAINS ACROSS ZAPATA, JIM HOGG, STARR, BROOKS, AND NORTHERN
HIDALGO COUNTIES, GENERALLY NUDGING EASTWARD THROUGH THE RIO
GRANDE VALLEY AND LOWER TEXAS COAST WITH THE FRONTAL PASSAGE
THROUGH LATE THIS WEEKEND.
AREAS OF ADVANCED DROUGHT CONDITIONS MAY EXPERIENCE EXCESSIVE
RUNOFF WHERE ANY HEAVY RAIN PERSISTS. THERE IS SOME CONCERN FOR
FLASH FLOODING WHERE HEAVIER RAIN AND EXCESSIVE RUNOFF OCCURS
THURSDAY INTO SATURDAY, ESPECIALLY ACROSS THE BRUSH COUNTRY, WHERE
FLASH FLOODING IS MORE COMMON. THE WEATHER PREDICTION CENTER HAS
CONTINUED A MODERATE RISK (AT LEAST 40 PERCENT CHANCE) OF FLOODING
RAINFALL ACROSS ZAPATA, JIM HOGG, AND STARR COUNTIES THURSDAY
THROUGH THURSDAY NIGHT, WITH A SLIGHT RISK (AT LEAST 15-25 PERCENT
CHANCE) OF FLOODING RAINFALL ACROSS THE REMAINDER OF DEEP SOUTH
TEXAS, INCLUDING THE RIO GRANDE VALLEY. THE CHANCE OF FLOODING
RAINFALL CONTINUES FRIDAY INTO SATURDAY ACROSS ALL OF DEEP SOUTH
TEXAS AND ALONG THE COAST SATURDAY INTO MONDAY.
RAINFALL AMOUNTS OF GENERALLY 2 TO 4 INCHES ARE EXPECTED ACROSS
DEEP SOUTH TEXAS AND THE RIO GRANDE VALLEY INTO SATURDAY, WITH AN
ADDITIONAL 1 TO 3 INCHES OF RAINFALL EXPECTED INTO MONDAY, AND
LOCALLY HIGHER AMOUNTS WHERE ANY HEAVIER RAINFALL PERSISTS. THE
LATEST 48-HR PROBABILISTIC GUIDANCE INDICATES THERE IS A LOW (10
PERCENT) CHANCE OF UP TO 4 TO 6 INCHES ACROSS AREAS GENERALLY WEST
OF US281/I69C INTO SATURDAY MORNING, WITH AN ADDITIONAL 2 TO 3
INCHES BY MONDAY MORNING, MAINLY ALONG AND EAST OF US281/I69C.
HAVE HELD OFF ON ANY FLOOD WATCHES AT THIS TIME BUT WILL CONTINUE
TO MONITOR THROUGH THE SHIFT.
EXPECT A BREEZY AFTERNOON CONTINUING OVERNIGHT INTO THURSDAY AS
THE PRESSURE GRADIENT STRENGTHENS AND A LLJ SETS UP OVERNIGHT.
THE INCREASED CHANCE OF RAIN AND CLOUD COVER, AS WELL AS A
NORTHERLY WIND SHIFT BY THE WEEKEND INTO EARLY NEXT WEEK, WILL
BRING A TASTE OF FALL AND WELCOMED BREAK TO THE HEAT, WITH BELOW
NORMAL TEMPERATURES SATURDAY INTO EARLY NEXT WEEK. WILL CONTINUE
TO MONITOR BEACH AND MARINE HAZARDS OVER THE WEEKEND, WITH A
POTENTIAL FOR TIDAL RUN-UP AND ELEVATED RISK OF LIFE-THREATENING
RIP CURRENTS.
AVIATION
(18Z TAFS)
ISSUED AT 1247 PM CDT WED SEP 30 2026
VFR CONDITIONS ARE EXPECTED TO GENERALLY PREVAIL THROUGH THE TAF
PERIOD WITH BREEZY SOUTHEASTERLY WINDS THIS AFTERNOON INTO
THURSDAY. THERE IS A LOW CHANCE OF AN ISOLATED SHOWER OR
THUNDERSTORM OVER THE NEXT COUPLE OF HOURS AND A HIGHER CHANCE OF
SHOWERS AND THUNDERSTORMS THURSDAY AFTERNOON, JUST BEYOND THIS TAF
PERIOD.
MARINE
ISSUED AT 1247 PM CDT WED SEP 30 2026
THE PRESSURE GRADIENT TIGHTENS ALONG THE LOWER TEXAS COAST INTO
THURSDAY AS AN UPPER LEVEL LOW AND SLOW-MOVING FRONTAL BOUNDARY
WORK THROUGH TEXAS AND APPROACH COASTAL WATERS. EXPECTED SEAS TO
BUILD INTO THURSDAY WITH SCEC TO BORDERLINE SCA CONDITIONS. LIGHT
TO MODERATE NORTHERLY WINDS ARE EXPECTED BEHIND THE FRONTAL
BOUNDARY SATURDAY INTO EARLY NEXT WEEK WITH FALL-LIKE CONDITIONS,
INCLUDING LIGHT RAIN OR DRIZZLE AND DECREASED VISIBILITY,
ESPECIALLY NEAR THE COAST.
HYDROLOGY
ISSUED AT 1247 PM CDT WED SEP 30 2026
THERE IS AN INCREASED THREAT OF HEAVY RAINFALL ALONG THE RIO
GRANDE INTO THIS WEEKEND WHICH WILL LEAD TO A RISE IN WATER LEVELS
ALONG THE RIO GRANDE, MAIN FLOODWAY, NORTH FLOODWAY, AND ARROYO
COLORADO INTO NEXT WEEK. THE FALCON RESERVOIR REMAINS VERY LOW AND
HAS PLENTY OF ROOM TO HOLD ANY INCREASED FLOW ALONG THE RIO
GRANDE. FOR ANY INTERESTS STATIONED OR POSITIONED WITHIN LEVEES
DOWNSTREAM OF FALCON, INCLUDING ALONG THE FLOODWAYS AND ARROYO
COLORADO, THROUGH STARR, HIDALGO, AND CAMERON COUNTIES, PLEASE
CONTINUE TO MONITOR RIVER FORECASTS AND WATER LEVELS INTO NEXT
WEEK. AREAS THAT HAVE BEEN DRY FOR MONTHS MAY BECOME INUNDATED BY
THE WEEKEND OR EARLY NEXT WEEK WITH FLOWING WATER.
PRELIMINARY POINT TEMPS/POPS
BROWNSVILLE 83 97 81 95 / 20 30 50 70
HARLINGEN 80 100 76 97 / 20 50 50 80
MCALLEN 83 102 80 97 / 20 50 70 80
RIO GRANDE CITY 81 102 77 93 / 30 70 90 90
SOUTH PADRE ISLAND 84 90 83 89 / 20 20 40 40
BAYVIEW/PORT ISABEL 81 96 79 93 / 20 30 40 60
BRO WATCHES/WARNINGS/ADVISORIES
TX...NONE.
GM...NONE.
SHORT TERM...56-HALLMAN
LONG TERM....56-HALLMAN
AVIATION...56-HALLMAN
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