FXUS64 KBRO 091735 AAB AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 1235 PM CDT Thu Jul 9 2026 ...New AVIATION... .KEY MESSAGES... Updated at 1222 PM CDT Thu Jul 9 2026 * Hot summer conditions continue through the week. Moderate (level 2 of 4) risk of heat-related illness each day, mainly in the Valley becoming more widespread this weekend. Heat indices will climb to between 100 and 110 degrees each day. * Daily rain and thunderstorm chances will increase from 10-25% today to 25-50% Friday/Saturday. While severe weather is not expected, any storms that develop are capable of heavy to torrential rainfall, gusty winds and small hail. * There is generally a low risk of rip currents at area beaches likely increasing to moderate this weekend. && .DISCUSSION... Issued at 1049 PM CDT Wed Jul 8 2026 A seasonably hot forecast on tap for deep South Texas with daily chances of afternoon showers and thunderstorms and breezy afternoon winds. An inverted trough at the surface will continue to push deep tropical moisture northward today into this weekend, gradually increasing rain chances. Convection over the Gulf slowly heading northward may bring isolated showers and thunderstorms late this morning. Depending on coverage (ie, lesser coverage and more surface heating during the morning), isolated to scattered showers and thunderstorms along the sea breeze are possible this afternoon. Rain chances increase to low-moderate (20-50%) Friday and Saturday as PWATs climb to 2.0 to 2.3 inches. Most activity is anticipated in the afternoon along the sea breeze or along outflow boundaries. While widespread flooding is not anticipated, storms will be capable of producing efficient rainfall rates and localized heavy downpours, especially under slow-moving or training convection. Given relatively dry antecedent conditions and high flash flood guidance, any flooding concerns should remain localized, though isolated nuisance flooding in poor drainage areas cannot be ruled out. Rain chances taper back to isolated coverage Sunday into early next week as ridging builds over central CONUS, shifting deeper moisture away from the region. Confidence decreases late in the period as guidance continues to differ on the evolution of an approaching frontal boundary. Temperatures will remain seasonable through the forecast, with afternoon highs generally in the mid to upper 90s (upper 80s along the coast). Combined with persistent Gulf humidity, peak heat index values of 104 to 110 degrees will support a moderate risk of heat related illness. Along the coast, long-period swell and astronomical tides may increase risk of rip currents and further narrow beaches near high tide. && .AVIATION... (18Z TAFS) Issued at 1222 PM CDT Thu Jul 9 2026 An area of convection just offshore the Lower Texas coast has resulted in VCTS reported at KBRO at this time, though the closest detected lightning has been around 45+ SM to the east. PROB30s have been introduced to the 18Z TAF cycle as the moisture over the Gulf begins to work its way inland via the seabreeze boundary; ongoing cloud cover could result in VCSH for KBRO and KHRL later this afternoon and into the early evening hours, yet abundant sunshine and enhanced inland instability may lead to VCTS at KMFE. Chances of rain decrease into the later evening and early night hours tonight before increasing back to a low chance late tonight and into tomorrow afternoon for KBRO and KHRL as showers and thunderstorms develop. Southeasterly winds of around 10-15 knots, with gusts up to around 20-25 knots this afternoon decrease back to gentle tonight into midday tomorrow as VFR conditions prevail, though brief periods of reduced instability are possible from potential heavy rain within showers and thunderstorms that develop. && .MARINE... Issued at 1049 PM CDT Wed Jul 8 2026 Moderate southerly to onshore flow with slight seas persists today. Isolated to scattered showers and thunderstorms are possible each day into the weekend, bringing briefly gusty winds, heavy rain, and elevated seas. This weekend, slight seas build to moderate into next week with increasing swells. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 78 92 81 94 / 40 40 10 10 HARLINGEN 75 93 78 95 / 30 40 10 20 MCALLEN 78 96 81 98 / 10 30 10 10 RIO GRANDE CITY 76 96 79 99 / 10 20 10 20 SOUTH PADRE ISLAND 80 87 82 88 / 50 40 20 10 BAYVIEW/PORT ISABEL 77 90 80 92 / 40 40 20 10 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM...99 LONG TERM....99 AVIATION...65-Irish