698
FXUS64 KBRO 280550 AAA
AFDBRO
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1250 AM CDT MON SEP 28 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 1245 AM CDT MON SEP 28 2026
- HOTTER THAN NORMAL TEMPERATURES WILL CONTINUE THROUGH THURSDAY.
- WIDESPREAD MAJOR (LEVEL 3 OUT OF 4) HEAT RISK WITH POCKETS OF
EXTREME (LEVEL 4 OF 4) HEAT RISK TO CONTINUE ACROSS THE REGION
THROUGH THURSDAY.
- HEAT SPIKES ARE POSSIBLE TUESDAY-THURSDAY WITH DANGEROUS HEAT
INDICES RANGING BETWEEN 105-115F DEGREES; SPECIAL WEATHER
STATEMENTS (SPSS) AND HEAT ADVISORIES MAY BE NEEDED.
- CONFIDENCE IS INCREASING ON A SIGNIFICANT WEATHER PATTERN
CHANGE TOWARDS MARKEDLY COOLER AND WETTER CONDITIONS LATER
THIS WEEK; THIS INCLUDES A MULTI-DAY HEAVY RAIN AND FLASH FLOOD
POTENTIAL THURSDAY THROUGH EARLY NEXT WEEK.
- PRELIMINARY RAINFALL AMOUNTS OF 2-4 INCHES WITH LOCALLY HIGHER
AMOUNTS IS POSSIBLE THURSDAY THROUGH NEXT SUNDAY NIGHT.
- THE WEATHER PREDICTION CENTER (WPC) HAS ALL OF DEEP SOUTH TEXAS
UNDER A SLIGHT (LEVEL 2 OF 4) RISK FOR EXCESSIVE RAINFALL FOR
THURSDAY (DAY 5).
- BREEZY SOUTHEAST WINDS 15-25 MPH WITH GUSTS UP TO 35 MPH OR SO
WILL RESULT IN SCEC TO SMALL CRAFT ADVISORIES FOR THE LAGUNA
MADRE AND THE GULF TUESDAY AND WEDNESDAY AS WELL AS INCREASED
RIP CURRENT RISKS ALONG THE BEACHES.
DISCUSSION
ISSUED AT 1113 PM CDT SUN SEP 27 2026
THE TWO MAIN WEATHER STORYLINES FOR THE WEEK AHEAD IS 1) THE HEAT
THROUGH THURSDAY, AND 2) THE INCREASING CHANCES FOR A SIGNIFICANT
WEATHER PATTERN SHIFT, FEATURING WETTER AND COOLER CHANGES, COURTESY
OF THE INFLUENCES OF A STRONG EL NINO LATER THIS WEEK.
WE START OFF THE FORECAST PERIOD TONIGHT WHERE DRY, WARM, AND HUMID
CONDITIONS WILL PERSIST UNDER PARTLY CLOUDY TO MOSTLY CLOUDY SKIES.
THE HEAT STORYLINE
THE STRONG HEAT DOME THAT'S PLAGUED DEEP SOUTH TEXAS AND THE RIO
GRANDE VALLEY OVER THE PAST WEEK IS CURRENTLY WEAKENING. DESPITE THE
WEAKENING OF THE HEAT DOME, IT'S INFLUENCE OVERHEAD WILL BE STRONG
ENOUGH TO CONTINUE YIELDING MAINLY RAIN-FREE AND HOTTER THAN NORMAL
TEMPERATURES THROUGH WEDNESDAY NIGHT. DURING THIS TIME, HIGH
TEMPERATURES WILL RANGE BETWEEN THE UPPER 90S TO LOWER 100S. A HEAT
SPIKE IS POSSIBLE TUESDAY THROUGH THURSDAY, AHEAD OF THE COMING
PATTERN CHANGE. DEEP TROPICAL MOISTURE FROM THE GULF AND THE EASTERN
EQUATORIAL PACIFIC WILL STREAM INTO THE REGION, TUESDAY THROUGH
THURSDAY. THOUGH THE AFOREMENTIONED HEAT DOME WILL BE WEAKENING, IT
WILL BE STRONG ENOUGH FOR HOT TEMPERATURES TO PERSIST. THESE HOT
TEMPERATURES COMBINED WITH AN INFLUX OR SURGE OF MOISTURE WILL
RESULT IN DANGEROUSLY HOT HEAT INDICES TUESDAY THROUGH THURSDAY.
FORECASTED PEAK HEAT INDICES DURING THIS TIME IS EXPECTED TO RANGE
BETWEEN 105-115F DEGREES. THIS WILL TRIGGER WIDESPREAD MAJOR
(LEVEL 3 OF 4) WITH POCKETS OF EXTREME (LEVEL 4 OF 4 ) HEAT RISK
DURING THIS TIMEFRAME. SPECIAL WEATHER STATEMENTS AND HEAT
ADVISORIES MAY BE NEEDED TO ACCOUNT FOR THE SURGE IN DANGEROUSLY
HOT HEAT INDICES. VERY WARM OVERNIGHT LOW TEMPERATURES IN THE
UPPER 70S TO LOWER 80S WILL PROVIDE LITTLE TO NO RELIEF.
IT'S ALSO WORTH NOTING THAT TUESDAY AND WEDNESDAY WILL BE QUITE
BREEZY. AN APPROACHING COOL FRONT FROM NORTHWESTERN TEXAS AND A
LARGE BERMUDA HIGH TO THE EAST WILL RESULT IN AN ENHANCED PRESSURE
GRADIENT AHEAD OF THE PATTERN CHANGE THAT'S TO COME. THIS WILL
RESULT IN BREEZY SOUTHEASTERLY WINDS 15-25 MPH GUSTING AS HIGH AS 35
MPH OR SO TUESDAY AND WEDNESDAY. THESE WINDS COULD TRIGGER SMALL
CRAFT EXERCISE CAUTION (SCEC) AND SMALL CRAFT ADVISORIES ALONG THE
LAGUNA MADRE AND PARTS OF THE GULF (SEE MARINE SECTION). THESE WINDS
WILL HELP IN AIDING MOIST AND WARM AIR ADVECTION (WAA) DURING THIS
TIME.
THE MAJOR WEATHER PATTERN CHANGE STORYLINE
AS TOUCHED ON IN THE PREVIOUS SECTION, CONFIDENCE CONTINUES TO
INCREASE ON A SIGNIFICANT WEATHER PATTERN FEATURING MARKEDLY WETTER
AND COOLER CONDITIONS, AFTER SUCH A BRUTALLY HOT AND DRY FEW MONTHS.
FORECAST MODELS/ENSEMBLES CONTINUE TO SHOW HURRICANE POLO MAKING
LANDFALL OVER THE BAJA PENINSULA OF CALIFORNIA BEFORE TRACKING OVER
NORTHERN MEXICO AND EVENTUALLY NORTHERN TEXAS MONDAY THROUGH
WEDNESDAY OF THIS WEEK. ALONG WITH THE RE-CURVATURE OF HURRICANE
POLO, DEEP TROPICAL MOISTURE FROM THE EASTERN PACIFIC WILL STREAM
WILL BEGIN TO STREAM INTO THE REGION FROM THE WEST-SOUTHWEST.
MEANWHILE, DEEP TROPICAL MOISTURE FROM THE GULF OF AMERICA WILL
BEGIN TO STREAM INTO THE REGION FROM THE SOUTH, COURTESY OF A LARGE
BERMUDA HIGH TO THE EAST.
MEANWHILE, DURING THIS SAME TIME, A SOUTHEASTWARD ADVANCING COOL
FRONT IS EXPECTED TO TRACK ACROSS TEXAS GRADUALLY APPROACHING DEEP
SOUTH TEXAS BEFORE POSSIBLY STALLING JUST TO OUR NORTH. MEANWHILE,
THERE ARE INDICATIONS OF A WEAK SHORTWAVE TROUGH AND MID-UPPER
ENERGIES RESIDING NEAR DEEP SOUTH TEXAS AND NORTHEAST MEXICO. THE
COMBINATION OF A NEARBY MID-UPPER IMPULSES, A NEARBY
STALLED/STALLING COOL FRONT, AND THE INFLUX OF DEEP TROPICAL
MOISTURE FROM BOTH THE GULF OF AMERICA AND THE EASTERN EQUATORIAL
PACIFIC OCEAN WILL SUPPORT WIDESPREAD CHANCES FOR SHOWERS AND
THUNDERSTORMS LATER THIS WEEK.
OVER THE PAST 24-48 HOURS, THE TIMING HAS SCALED BACK SOME. SO
INSTEAD OF THE RAIN BEGINNING ON WEDNESDAY, THE RAINS ARE EXPECTED
TO ARRIVE THURSDAY AFTERNOON/EVENING. THESE RAINS ARE EXPECTED TO
PERSIST THROUGH NEXT WEEKEND AND POSSIBLY BEYOND. THESE
BREAKTHROUGH RAINS WILL EFFECTIVELY PUT A DENT TO THE D2 (SEVERE)
TO D4 (EXCEPTIONAL) DROUGHT OVER THE REGION. THIS HAS THE MAKINGS
OF A MULTI-DAY HEAVY RAINFALL AND FLASH FLOODING EVENT. RUN-OFF
AND FLASH FLOODING IS CERTAINLY POSSIBLE DUE TO 1) HOW HARD AND
IMPERVIOUS THE SOILS ARE, 2) HOW EFFICIENT THE RAINFALL WILL BE
GIVEN THE MOISTURE LADEN ENVIRONMENT, AND 3) THE LIKELIHOOD THAT
SHOWERS AND THUNDERSTORMS WILL TRACK OVER MANY OF THE SAME AREAS
AND COULD BE SLOW-MOVERS (ATMOSPHERIC RIVER-LIKE). NOW IS THE TIME
TO BEGIN PREPARING FOR THIS MULTI-DAY HEAVY RAIN AND POTENTIAL
FLASH FLOODING EVENT. THAT INCLUDES CHECKING YOUR TIRES, BRAKES,
WIPERS, CLEARING SEWERS, DRAINAGES, ETC. SEE
WEATHER.GOV/SAFETY/FLOOD FOR MORE TIPS ON FLOOD SAFETY.
THAT SAID, WE HAVE MEDIUM-HIGH OR CATEGORICAL POPS RANGING BETWEEN
40-80% FOR MOST OF THE TIME PERIOD FROM THURSDAY INTO MONDAY OF THE
FOLLOWING WEEK (OCT 1-5, 2026). PRELIMINARY RAINFALL AMOUNTS BETWEEN
WEDNESDAY NIGHT AND SUNDAY NIGHT RANGE BETWEEN 2-4 INCHES WITH
LOCALLY HIGHER AMOUNTS. FINALLY, THE WEATHER PREDICTION CENTER (WPC)
HAS ALL OF DEEP SOUTH TEXAS AND THE RIO GRANDE VALLEY UNDER A SLIGHT
RISK (LEVEL 2 OF 4) FOR EXCESSIVE RAINFALL FOR THURSDAY.
THIS IS THE POTENTIAL PATTERN SHIFT THAT WE'VE BEEN CLOSELY
MONITORING, AND IF REALIZED, WILL BRING THE BREAKTHROUGH RAINS THAT
WE'VE BEEN WAITING FOR SO LONG AS WELL AS A NOTABLY COOLER PATTERN
DUE TO THE INCREASE CLOUD COVERAGE AND RAINS. THIS POTENTIAL PATTERN
SHIFT TO START OCTOBER HAS EL NINO WRITTEN ALL OVER IT. AGAIN, WE
WILL CONTINUE TO CLOSELY MONITOR FORECAST TRENDS IN THE DAYS AHEAD
AND FINE TUNE THE FORECAST AS NEEDED.
AVIATION
(06Z TAFS)
ISSUED AT 1245 AM CDT MON SEP 28 2026
LIGHT AND VARIABLE WINDS PREVAIL ACROSS DEEP SOUTH TEXAS EARLY
THIS MORNING. LIGHT WINDS OVERNIGHT WILL BECOME EAST TO SOUTHEAST
BETWEEN 5 TO 10 KNOTS LATER THIS MORNING INTO THE AFTERNOON. SOME
WIND GUSTS BETWEEN 15 TO 20 KNOTS WILL BE POSSIBLE IN THE AFTERNOON.
WINDS ARE EXPECTED TO DECREASE LATER THIS EVENING. VFR CONDITIONS
WILL CONTINUE FOR THE NEXT 24 HOURS.
MARINE
ISSUED AT 1113 PM CDT SUN SEP 27 2026
GENERALLY, FAVORABLE MARINE CONDITIONS WILL PERSIST THROUGH MONDAY
WITH LOW TO MODERATE SEAS (WAVE HEIGHTS BETWEEN 1-3 FEET) AND WINDS.
TUESDAY NIGHT AND POINTS FORWARD, CONDITIONS WILL BECOME MORE
ADVERSE DUE TO INCREASED WINDS TUESDAY AND WEDNESDAY, THE THREAT
FOR SHOWERS AND THUNDERSTORMS, AND INCREASING SEAS. SCEC TO SMALL
CRAFT ADVISORIES MAY BE NEEDED IN THE TUESDAY NIGHT THROUGH
SATURDAY TIMEFRAME.
PRELIMINARY POINT TEMPS/POPS
BROWNSVILLE 96 80 96 82 / 10 10 20 10
HARLINGEN 99 77 100 78 / 10 10 30 10
MCALLEN 102 80 102 82 / 0 10 10 0
RIO GRANDE CITY 102 78 103 80 / 0 0 0 0
SOUTH PADRE ISLAND 89 82 89 83 / 10 20 20 10
BAYVIEW/PORT ISABEL 94 78 94 80 / 10 10 30 10
BRO WATCHES/WARNINGS/ADVISORIES
TX...NONE.
GM...NONE.
SHORT TERM...23-EVBUOMA
LONG TERM....23-EVBUOMA
AVIATION...63-KC
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