792
FXUS64 KBRO 291120
AFDBRO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
620 AM CDT TUE SEP 29 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 620 AM CDT TUE SEP 29 2026
- 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.
- CONFIDENCE IS INCREASING ON A SIGNIFICANT WEATHER PATTERN
CHANGE TOWARDS COOLER AND WETTER CONDITIONS LATER THIS WEEK;
THIS INCLUDES A MULTI-DAY HEAVY RAIN AND FLASH FLOOD POTENTIAL
THURSDAY INTO THE WEEKEND.
- THE WEATHER PREDICTION CENTER (WPC) HAS ALL OF DEEP SOUTH TEXAS
UNDER A SLIGHT (LEVEL 2 OF 4) TO MODERATE (LEVEL 3 OF 4) RISK
FOR EXCESSIVE RAINFALL FOR THURSDAY, AND A MARGINAL (LEVEL 1 OF
4) TO SLIGHT RISK FRIDAY AND SATURDAY.
DISCUSSION
ISSUED AT 1103 PM CDT MON SEP 28 2026
AN UPPER LEVEL TROUGH OVER THE SOUTHWEST WILL INGEST DEEP
TROPICAL MOISTURE FROM THE PACIFIC EARLY THIS WEEK. AS THE TROUGH
MOVES FURTHER EAST, AN ACCOMPANYING COLD FRONT IS FORECAST TO PUSH
INTO CENTRAL TEXAS, BEFORE LIKELY STALLING MID-WEEK. LOCALLY,
CONTINUED SOUTHEASTERLY LOW LEVEL FLOW WILL ADVECT ADDITIONAL WARM
AND HUMID AIR FROM THE GULF ACROSS DEEP SOUTH TEXAS. IN THE SHORT
TERM, THIS WILL CONTINUE TO SUPPORT DAILY HEAT CONCERNS WITH
AFTERNOON HEAT INDEX VALUES RANGING FROM 105-115. HEAT ADVISORIES
MAY BE NEEDED DAILY THROUGH THURSDAY.
AS THE TROUGH CONTINUES MOVING EASTWARD, INCREASED FORCING ACROSS
EASTERN TEXAS, COMBINED WITH PWATS RANGING FROM 2-2.5 INCHES WILL
LIKELY RESULT IN WIDESPREAD RAINFALL ACROSS DEEP SOUTH TEXAS
THURSDAY AFTERNOON INTO THE WEEKEND. THE HEAVIEST RAINFALL IS MOST
LIKELY TO OCCUR THURSDAY AND FRIDAY, WITH PROBABILISTIC MODELS
SUPPORTING 48 HOUR RAINFALL ACCUMULATIONS FROM 7 AM THURSDAY
THROUGH 7 AM SATURDAY RANGING FROM 0.5-3 INCHES ACROSS THE MID AND
LOWER RIO GRANDE VALLEY AND 2 TO 4 INCHES FURTHER WEST. THE
WEATHER PREDICTION CENTER HAS ALL OF DEEP SOUTH TEXAS IN A SLIGHT
RISK (LEVEL 2 OF 4) FOR EXCESSIVE RAINFALL THURSDAY, AND A
MARGINAL RISK (LEVEL 1 OF 4) FOR EXCESSIVE RAINFALL ACROSS THE
COASTAL COUNTIES, WITH ANOTHER SLIGHT RISK OVER INLAND COUNTIES
FRIDAY.
THE BULK OF THE MODEL GUIDANCE SUGGEST THAT THE STALLED FRONTAL
BOUNDARY MAY RESUME ITS SOUTHEASTWARD MOTION FRIDAY, BRINGING THE
COLD FRONT THROUGH DEEP SOUTH TEXAS FRIDAY AFTERNOON INTO FRIDAY
EVENING. LIGHT NORTHERLY SURFACE FLOW BEHIND THE FRONT COULD
SUPPORT COOLER TEMPERATURES OVER THE WEEKEND, WITH HIGH
TEMPERATURES IN THE MID 80S TO LOW 90S AND OVERNIGHT LOWS IN THE
LOW TO MID 70S. EASTERLY TO SOUTHEASTERLY MID LEVEL FLOW WILL
LIKELY CONTINUE THROUGH THE WEEKEND, RESULTING IN AN OVERRUNNING
PATTERN THAT WILL SUPPORT OVERCAST SKIES WITH GENERALLY LIGHT
RAIN.
AVIATION
(12Z TAFS)
ISSUED AT 620 AM CDT TUE SEP 29 2026
VFR WILL PREVAIL THROUGH THE FORECAST PERIOD. THERE IS LOW CHANCE
OF SEA BREEZE SHOWERS/STORMS LATE THIS MORNING AND AFTERNOON, BUT
CONFIDENCE IS TOO LOW TO WARRANT A MENTION IN THE TAF AT THIS
TIME. OTHERWISE, EXPECT SOUTHERLY TO SOUTHEASTERLY WINDS AROUND
10-15 KNOTS WITH GUSTS UP TO 20 KNOTS LATE THIS MORNING THROUGH
THE LATE EVENING HOURS. WINDS SHOULD SUBSIDE LATE THIS EVENING
BELOW 10 KNOTS.
MARINE
ISSUED AT 1103 PM CDT MON SEP 28 2026
WINDS AND SEAS ALONG THE LOWER TEXAS COAST ARE FORECAST TO BEGIN
INCREASING TUESDAY WITH ADDITIONAL INCREASES ANTICIPATED MID WEEK
AS PRESSURE GRADIENTS TIGHTEN AHEAD OF AN APPROACHING COLD FRONT.
THIS WILL LIKELY LEAD TO ADVERSE CONDITIONS ON THE GULF AND LAGUNA
MADRE WITH HAZARDOUS CONDITIONS POSSIBLE LATER IN THE WEEK. SMALL
CRAFT SHOULD EXERCISE CAUTION HEADLINES WILL LIKELY BE NEEDED
BEGINNING TUESDAY, AND SMALL CRAFT ADVISORIES MAY BE NEEDED
THURSDAY AND FRIDAY.
THE COLD FRONT IS FORECAST TO MOVE THROUGH THE AREA FRIDAY
EVENING, WITH LIGHT NORTHEASTERLY WINDS BEHIND THE FRONT
SUPPORTING LOWER SEAS THROUGH THE WEEKEND.
RAIN CHANCES ARE FORECAST TO INCREASE THURSDAY AFTERNOON, WITH
WIDESPREAD RAINFALL LIKELY THROUGH THE WEEKEND
PRELIMINARY POINT TEMPS/POPS
BROWNSVILLE 96 82 97 82 / 30 10 0 20
HARLINGEN 100 78 101 80 / 20 10 0 10
MCALLEN 102 82 103 83 / 10 10 10 10
RIO GRANDE CITY 103 80 104 81 / 0 0 0 10
SOUTH PADRE ISLAND 90 83 90 83 / 30 10 10 30
BAYVIEW/PORT ISABEL 95 80 96 80 / 30 10 10 20
BRO WATCHES/WARNINGS/ADVISORIES
TX...NONE.
GM...NONE.
SHORT TERM...60
LONG TERM....60
AVIATION...22-GARCIA
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