145
FXUS64 KBRO 181737
AFDBRO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1237 PM CDT THU JUN 18 2026
..NEW DISCUSSION, AVIATION, MARINE
KEY MESSAGES
UPDATED AT 1219 PM CDT THU JUN 18 2026
* AN EXTREME HEAT WARNING IS IN EFFECT TODAY UNTIL 8 PM CDT. HEAT
INDICES EXCEEDING 120 DEGREES ARE EXPECTED THROUGHOUT DEEP SOUTH
TEXAS THIS AFTERNOON AND EARLY EVENING.
* LITTLE RELIEF FROM THE HEAT IS EXPECTED TONIGHT (HEAT INDICES ARE
EXPECTED TO REMAIN ABOVE 90). AN EXTREME HEAT WATCH IS IN EFFECT
TOMORROW FROM 11 AM TO 8 PM CDT.
* THERE IS A LOW TO MODERATE (20 TO 40%) CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE WESTERN RANCHLANDS FRIDAY AND SATURDAY
NIGHT. LOW TO MODERATE CHANCES EXTEND TO ALL OF DEEP SOUTH
TEXAS DURING THE DAY ON SATURDAY.
* A MODERATE RISK OF RIP CURRENTS CONTINUES FOR AREA BEACHES THROUGH
TOMORROW AFTERNOON.
* A SMALL CRAFT ADVISORY IS IN EFFECT THIS AFTERNOON THROUGH
TOMORROW MORNING.
DISCUSSION
ISSUED AT 1219 PM CDT THU JUN 18 2026
AN EXTREME HEAT WARNING IS IN EFFECT FOR ALL OF DEEP SOUTH TEXAS
(EXCEPTING THE BARRIER ISLANDS) THIS AFTERNOON AND EVENING UNTIL 8
PM CDT. HEAT INDICES OF 120 OR HIGHER ARE POSSIBLE FOR THE ENTIRE
REGION TODAY (EXCEPTING THE ISLANDS), WHICH ARE THE HIGHEST HEAT
INDICES WE HAVE HAD SINCE 2024. IN ADDITION, AN EXTREME HEAT
WATCH IS ALSO IN EFFECT FOR FRIDAY AS WELL, WITH LITTLE RELIEF
FROM THE HEAT EXPECTED OVERNIGHT. THE HEAT INDEX IS LIKELY TO STAY
ABOVE 90 DEGREES OVERNIGHT, AND CLIMB BACK UP BETWEEN 115 AND 120
DEGREES TOMORROW. TOMORROW'S EXTREME HEAT WATCH MAY NEED TO BE
UPGRADED TO A WARNING LATER THIS EVENING.
MODERATE TO MAJOR HEAT RISK CONCERN WILL CONTINUE INTO THE
WEEKEND, AND WHILE HEAT INDICES WILL NOT BE AS HIGH AS TODAY AND
TOMORROW, THE HEAT INDEX IN SOME PLACES COULD EXCEED 110 DEGREES
IN SOME AREAS (ESPECIALLY IN THE LOWER RIO GRANDE VALLEY) SATURDAY
THROUGH MONDAY. ADDITIONAL HEAT ADVISORIES MAY BE NEEDED OVER THE
WEEKEND. CONDITIONS SHOULD SLIGHTLY IMPROVE ON TUESDAY, BUT THE
HEAT INDEX WILL STILL REACH THE TRIPLE DIGITS. ACTUAL
TEMPERATURES WILL LOWER FROM THE UPPER 90S/LOWER 100S THIS WEEKEND
TO THE MID-TO-UPPER 90S BY MID-WEEK. HOWEVER, THE HEAT INDEX IS
MORE REPRESENTATIVE OF HOW HOT IT IS GOING TO FEEL OUTSIDE OVER
THE NEXT SEVERAL DAYS.
CONDITIONS SHOULD BE OVERALL RAIN-FREE THROUGHOUT THE NEXT WEEK, BUT
A WEAK MID-LEVEL DISTURBANCE IS EXPECTED TO ENHANCE THE POTENTIAL
FOR SIERRA MADRE CONVECTION TO FORM IN MEXICO AND MOVE EASTWARD INTO
OUR CWA STARTING FRIDAY EVENING. THE WESTERN RANCHLAND COUNTIES
COULD SEE SOME SHOWERS AND THUNDERSTORMS (20 TO 40% LIKELIHOOD)
FRIDAY NIGHT. THESE SAME LOW TO MODERATE CHANCES THEN SPREAD
ACROSS DEEP SOUTH TEXAS ON SATURDAY BEFORE THE WESTERN RANCHLANDS
COULD SEE ANOTHER ROUND OF SIERRA MADRE SHOWERS AND THUNDERSTORMS
SATURDAY NIGHT AS WELL. FLOODING SHOULDN'T BE TOO MUCH OF A
CONCERN FOR MOST PLACES, BUT AN ISOLATED FLASH FLOOD CANNOT BE
RULED OUT IF AN AREA THAT ALREADY RECEIVED HEAVY RAINFALL EARLIER
THIS WEEK ALSO RECEIVES LOCALIZED HEAVY RAINFALL THIS WEEKEND.
THEREFORE, THE WEATHER PREDICTION CENTER HAS INCLUDED DEEP SOUTH
TEXAS IN A MARGINAL (LEVEL 1 OF 4) RISK OF EXCESSIVE RAINFALL FOR
SATURDAY.
A MODERATE RISK OF LIFE THREATENING RIP CURRENTS REMAINS IN PLACE
THROUGH TOMORROW.
AVIATION
(18Z TAFS)
ISSUED AT 1219 PM CDT THU JUN 18 2026
VFR CONDITIONS WITH CLEAR SKIES AND SOUTHEASTERLY WINDS ARE EXPECTED
AT ALL AIRPORTS THROUGH THIS EVENING. OVERNIGHT, CLOUDS WILL
DEVELOP BETWEEN 02-04Z AND CEILINGS SHOULD LOWER TO MVFR FOR HRL
AND BRO. MFE SHOULD REMAIN AT VFR BUT STILL DEVELOP SOME OVERNIGHT
CLOUDS.
MARINE
ISSUED AT 1219 PM CDT THU JUN 18 2026
A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE BAY AND NEARSHORE
WATERS THIS AFTERNOON THROUGH TOMORROW MORNING DUE TO ELEVATED
WIND GUSTS AND SEAS. THE OFFSHORE WATERS HAVE A SMALL CRAFT
ADVISORY IN EFFECT UNTIL 12Z TOMORROW MORNING STARTING AT 00Z.
INTERMITTENT PERIODS OF SCEC ARE POSSIBLE THIS WEEKEND THROUGH
EARLY NEXT WEEK UNTIL CONDITIONS IMPROVE TO MORE FAVORABLE BY
MIDWEEK.
PRELIMINARY POINT TEMPS/POPS
BROWNSVILLE 84 96 84 94 / 0 0 10 20
HARLINGEN 81 97 81 94 / 0 0 10 20
MCALLEN 83 98 83 95 / 0 10 20 40
RIO GRANDE CITY 81 100 80 95 / 0 20 30 30
SOUTH PADRE ISLAND 85 90 85 89 / 0 0 10 10
BAYVIEW/PORT ISABEL 83 94 83 92 / 0 0 10 20
BRO WATCHES/WARNINGS/ADVISORIES
TX...EXTREME HEAT WARNING UNTIL 8 PM CDT THIS EVENING FOR TXZ248>255-
351-353>355.
EXTREME HEAT WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING
FOR TXZ248>255-351-353>355.
GM...SMALL CRAFT ADVISORY UNTIL 7 AM CDT FRIDAY FOR GMZ130-132-135-
150-155.
SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 AM CDT FRIDAY
FOR GMZ170-175.
SHORT TERM...55-MM
LONG TERM....55-MM
AVIATION...55-MM
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