479
FXUS64 KBRO 091803
AFDBRO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
103 PM CDT SAT AUG 9 2025
..NEW MESOSCALE UPDATE, DISCUSSION, MARINE
.MESOSCALE UPDATE FOR ISOLATED SHOWERS AND/OR THUNDERSTORMS THIS
AFTERNOON INTO THIS EVENING... ISSUED AT 100 PM CDT SAT AUG 9
2025
POP GRIDS HAVE BEEN INCREASED TO GIVE A LOW (20-25%) CHANCE OF BRIEF
ISOLATED SHOWERS AND/OR THUNDERSTORMS THIS AFTERNOON TO MAINLY
THE LOWER AND MIDDLE RGV AS WELL AS SOUTHERN PORTIONS OF KENEDY
AND BROOKS COUNTIES. TEMPERATURES ACROSS THESE AREAS HAVE ALREADY
SURPASSED THIS MORNING'S 12Z SOUNDING CONVECTIVE TEMPERATURE OF 89
DEGF AND RADAR SCANS OVER THE LAST HOUR HAVE DISPLAYED ISOLATED
SHOWERS FORMING ALONG THE SEABREEZE BOUNDARY, INITIATING ALONG THE
COASTAL PORTIONS OF CAMERON COUNTY, BEGINNING TO MOVE WESTWARD
AND FURTHER INLAND. THIS ACTIVITY IS EXPECTED TO CONTINUE TO
SPREAD WESTWARD INTO THE AREAS MENTIONED ABOVE. ADDITIONALLY,
POP'S HAVE BEEN INCREASED ACROSS THE GULF WATERS (0-60 NM) TO
REFLECT THE CURRENT COVERAGE AND EXPECTED EVOLUTION OF SHOWERS
AND/OR THUNDERSTORMS, WHICH IS GENERALLY A LOW TO MEDIUM (15-30%)
CHANCE, HIGHEST OVER THE OFFSHORE (20-60 NM) GULF WATERS. ALL
ACTIVITY IS ANTICIPATED TO DISSIPATE BEYOND SUNSET THIS EVENING.
DISCUSSION
ISSUED AT 100 PM CDT SAT AUG 9 2025
ALTHOUGH THE HEAT WILL CONTINUE TO BE THE MAIN FOCUS OF THE
FORECAST, THERE EXISTS A LOW TO MEDIUM (20-30%) CHANCE OF AFTERNOON
AND EARLY EVENING SHOWERS AND THUNDERSTORMS ALONG THE SEABREEZE
BOUNDARY ACROSS DEEP SOUTH TEXAS AND THE RIO GRANDE VALLEY TOMORROW
THROUGH TUESDAY, WITH THE BEST CHANCES NEAR AND EAST OF I-69 C, DUE
TO REDUCED SUBSIDENCE ALOFT AS THE CWA BECOMES PLACED BETWEEN TWO
RIDGES. BRIEF HEAVY DOWNPOURS, FREQUENT LIGHTNING AND GUSTS UP TO 40
MPH ARE POSSIBLE. A LOW (20%) CHANCE CONTINUES INTO WEDNESDAY,
THOUGH LESS WIDESPREAD IN COVERAGE, AS RIDGING AND SUBSIDENCE ALOFT
BUILDS FROM A MID-LEVEL HIGH PRESSURE EXPANDING OVER THE EASTERN
GULF. THURSDAY INTO NEXT SATURDAY, LONG RANGE MODELS INDICATE THIS
HIGH MOVING WESTWARD ACROSS THE GULF STATES, POSSIBLY MOVING INTO
EAST TEXAS BY NEXT WEEKEND. THIS IS LIKELY TO LESSEN THE CHANCE OF
DAILY CONVECTION TO LESS THAN 15% THURSDAY ONWARD, RESULTING IN MORE
SUNSHINE. MEANWHILE, ONSHORE SOUTHEASTERLY SURFACE WINDS CONTINUE TO
ELEVATE RELATIVE HUMIDITY, POSSIBLY ENHANCING TOWARDS THE LATER PART
OF THE WEEK AND NEXT WEEKEND DUE TO THE POSSIBILITY OF MOISTURE
BUILDING AHEAD OF A POSSIBLE DISTURBANCE MOVING INTO THE BAY OF
CAMPECHE.
WHILE SEASONABLY AVERAGE TEMPERATURES CONTINUE THROUGH THE FORECAST,
MAXIMIZING IN THE UPPER 90'S/LOWER 100'S INLAND (MID/UPPER 80S ALONG
THE GULF COAST) IN THE AFTERNOON AND MINIMIZING IN THE MID/UPPER
70'S (LOWER 80'S AT THE COAST) OVERNIGHT, THE REDUCTION IN CLOUD
COVERAGE AND THE POTENTIAL FOR RISING MOISTURE CONTENT (PWAT'S
POSSIBLY EXCEEDING 2.0 IN.) COULD RESULT IN SPECIAL WEATHER
STATEMENTS, BEGINNING TUESDAY AS AFTERNOON HEAT INDICES COULD
SURPASS 110 DEGREES FOR A FEW HOURS HOURS IN SOME LOCATIONS. WHILE
CONFIDENCE IS LOW AT THIS TIME, HEAT ADVISORIES COULD BECOME A
POSSIBILITY BY FRIDAY AND SATURDAY. MINOR (LEVEL 1/4) TO MODERATE
(LEVEL 2/4) HEAT RISKS, WITH POCKETS OF MAJOR (LEVEL 3/4) IN THE RIO
GRANDE VALLEY, ON SUNDAY AND MONDAY ARE EXPECTED TO BECOME MOSTLY
MODERATE FOR TUESDAY AND WEDNESDAY, WITH THE EXPANSION OF MAJOR ON
THURSDAY TO CLOSE OUT THE FORECAST WITH MOSTLY MAJOR HEAT RISKS
FRIDAY AND SATURDAY.
AVIATION
(18Z TAFS)
ISSUED AT 1212 PM CDT SAT AUG 9 2025
VFR CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE TAF CYCLE WITH
MODERATE (10-15 KNOTS) SOUTHEASTERLY WINDS BECOMING GENTLE
FOLLOWING SUNSET AND THEN LIGHT AND VARIABLE OVERNIGHT TONIGHT.
THERE IS A LOW (LESS THAN 15%) CHANCE OF AN ISOLATED SHOWER OR
THUNDERSTORM INTO THE REST OF THIS AFTERNOON, WHICH COULD BRIEFLY
LOWER CEILINGS TO MVFR, BUT THE PROBABILITY IS TOO LOW TO INCLUDE
IN THE TAF. OTHERWISE, MODERATE SOUTHEASTERLY WINDS PICK UP AGAIN
LATE SUNDAY MORNING INTO THE EARLY AFTERNOON HOURS.
MARINE
ISSUED AT 100 PM CDT SAT AUG 9 2025
FAVORABLE MARINE CONDITIONS PREVAIL INTO THE UPCOMING WEEK AS HIGH
PRESSURE OVER THE GULF CONTINUES TO RESULT IN MAINLY GENTLE
SOUTHEASTERLY TO SOUTHERLY WINDS AND SLIGHT (1-2 FT) SEAS, BECOMING
GENTLE TO MODERATE WITH SLIGHT TO MODERATE (1-3) FEET SEAS BY
WEDNESDAY AS A WEAK PRESSURE GRADIENT DEVELOPS. THERE IS A LOW (20%)
CHANCE OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS ACROSS
PORTIONS OF THE LAGUNA MADRE SUNDAY THROUGH TUESDAY AS WELL AS A
DAILY CHANCE ACROSS PORTIONS OF THE OFFSHORE (20-60 NM) GULF
WATERS.
PRELIMINARY POINT TEMPS/POPS
BROWNSVILLE 79 95 79 96 / 10 20 10 20
HARLINGEN 75 97 75 98 / 10 20 10 20
MCALLEN 79 101 79 101 / 10 20 10 20
RIO GRANDE CITY 77 102 78 102 / 10 10 10 20
SOUTH PADRE ISLAND 81 89 81 89 / 10 10 10 10
BAYVIEW/PORT ISABEL 77 92 78 94 / 10 20 10 20
BRO WATCHES/WARNINGS/ADVISORIES
TX...NONE.
GM...NONE.
MESOSCALE UPDATE...65-IRISH
DISCUSSION...65-IRISH
AVIATION...65-IRISH
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