688
FXUS64 KBRO 131756
AFDBRO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1256 PM CDT SUN SEP 13 2026
..NEW DISCUSSION, AVIATION, MARINE
KEY MESSAGES
UPDATED AT 1242 PM CDT SUN SEP 13 2026
- A HEAT ADVISORY IS IN EFFECT FOR THE MID TO LOWER RIO GRANDE
VALLEY AND THE COASTAL COUNTIES TODAY.
- WIDESPREAD EXTREME RISKS OF HEAT-RELATED ILLNESSES (LEVEL 4/4)
PREVAIL THROUGH MONDAY, GRADUALLY IMPROVING FROM A MAJOR (LEVEL
3/4) AND EXTREME RISK ON TUESDAY AND WEDNESDAY TO A MAINLY
MODERATE (LEVEL 2/4) RISK BY THURSDAY.
- ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON.
RAIN CHANCES INCREASE THROUGH THE LATER HALF OF THE WEEK.
DISCUSSION
ISSUED AT 1242 PM CDT SUN SEP 13 2026
WIDESPREAD TRIPLE DIGIT HIGH TEMPERATURES AND HEAT INDEX VALUES
RANGING FROM 108 TO 115 DEGREES WILL CONTINUE TO BE THE PRIMARY
CONCERN THROUGH MID WEEK. A BROAD UPPER LEVEL HIGH PRESSURE
SYSTEM OVER THE SOUTHEASTERN US WILL SHIFT FURTHER WEST THROUGH
MID WEEK,SUPPORTING BROAD SUBSIDENCE ALOFT THROUGH MID WEEK. THIS
PATTERN WILL SUPPORT GENERALLY RAIN FREE CONDITIONS MONDAY THROUGH
WEDNESDAY, THOUGH ISOLATED SEA BREEZE CONVECTION. MAJOR TO
EXTREME HEAT RISK IS FORECAST TO CONTINUE THROUGH MID-WEEK, AND
HEAT ADVISORIES MAY BE NEEDED EACH AFTERNOON.
FIRE WEATHER MAY BE A CONCERN TUESDAY, AS AFTERNOON RELATIVE
HUMIDITY VALUES FALL TO 20-30% ACROSS MOST OF THE CWA AS GUSTY
WINDS INCREASE THROUGH THE AFTERNOON. A BRIEF FIRE DANGER
STATEMENT MAY BE NEEDED TUESDAY.
A SHORTWAVE MOVING THROUGH THE SOUTHERN PERIPHERY OF THE HIGH
PRESSURE SYSTEM WILL LIKELY INCREASE FORCING AND MID-LEVEL
MOISTURE THROUGH THE LATER HALF OF THE WEEK, LEADING TO INCREASED
RAIN CHANCES THURSDAY AND FRIDAY, WITH THE HIGHEST RAIN CHANCES
ALONG THE COAST. INCREASED CLOUD COVER THROUGH THE LATER HALF OF
THE WEEK WILL LIKELY DROP HIGH TEMPERATURES TO THE UPPER 90S TO
AROUND 100.
AVIATION
(18Z TAFS)
ISSUED AT 1242 PM CDT SUN SEP 13 2026
VFR CONDITIONS ARE FORECAST TO CONTINUE THROUGH THE PERIOD. GUSTY
SOUTHEASTERLY WINDS WILL CONTINUE THIS AFTERNOON, WITH GUSTS
DIMINISHING THIS EVENING. CONVECTIVE MODELS HAVE CONTINUED TO BACK
OFF ON RAIN CHANCES THIS AFTERNOON, WITH RAIN CHANCES FORECAST TO
REMAIN NEAR ZERO AT ALL THREE TAF SITES.
MARINE
ISSUED AT 1242 PM CDT SUN SEP 13 2026
GENERALLY FAVORABLE MARINE CONDITIONS ARE FORECAST THROUGH THE
PERIOD, THOUGH ELEVATED WIND SPEEDS ALONG THE LAGUNA MADRE MAY
REQUIRED SMALL CRAFT SHOULD EXERCISE CAUTION HEADLINES EACH
AFTERNOON THROUGH WEDNESDAY. OTHERWISE, LIGHT TO MODERATE WINDS
AND SLIGHT TO MODERATE SEAS ARE FORECAST TO CONTINUE. DAILY RAIN
CHANCES WILL CONTINUE OVER THE GULF WATERS THIS WEEK, WITH RAIN
CHANCES INCREASING AND EXPANDING OVER THE LAGUNA MADRE THURSDAY
AND FRIDAY.
PRELIMINARY POINT TEMPS/POPS
BROWNSVILLE 81 98 81 98 / 20 10 0 0
HARLINGEN 77 102 77 102 / 10 10 0 0
MCALLEN 81 103 81 103 / 10 0 0 0
RIO GRANDE CITY 79 104 79 105 / 0 0 0 0
SOUTH PADRE ISLAND 82 90 83 90 / 20 10 10 0
BAYVIEW/PORT ISABEL 79 96 79 96 / 10 10 10 0
BRO WATCHES/WARNINGS/ADVISORIES
TX...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR TXZ251>255-351-
353>355.
GM...NONE.
SHORT TERM...60-BE
LONG TERM....60-BE
AVIATION...60-BE
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