textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1235 PM CDT Sat Jun 20 2026

- Scattered showers and thunderstorms are forecast to continue through the afternoon and evening today. Heavy rainfall associated with these storms may produce flash flooding, especially in areas that experience multiple or prolonged periods of heavy rain.

- The Weather Prediction Center has the majority of Deep South Texas under a Slight Risk for Excessive Rainfall (level 2 of 4) today.

- Drier conditions return Sunday, with high temperatures returning to the mid to upper 90s early next week.

DISCUSSION

Issued at 1235 PM CDT Sat Jun 20 2026

A very humid air mass remains in place across Deep South Texas today, with PWAT values generally ranging from 2.3-2.5 inches. Combined with CAPE values between 2000-3000 J/kg and forcing from a weak mid-level low along the Texas Coast, this will likely support the potential for scattered showers and thunderstorms capable of producing heavy rainfall this afternoon into the early overnight hours. The Weather Prediction Center has the majority of Deep South Texas under a Slight Risk of Excessive Rainfall (level 2 of 4) through tonight, while Brownsville and South Padre Island remain in a Marginal Risk (level 1 of 2). Rainfall totals of 1 to 2 inches are likely with locally higher amounts of 3-4 inches possible. Generally light cloud layer winds oriented along the weak forcing axis could support slow moving and training storms this afternoon, increasing the potential for flash flooding.

Conditions look to dry out early Sunday morning with near-zero rain chances returning through the remainder of the forecast. Increased cloud cover today and Sunday will help keep high temperatures in the low to mid 90s this weekend. With sunny skies returning Monday, high temperatures are forecast to climb to the mid to upper 90s through the remainder of the forecast. With lower humidity values forecast next week, heat indices will likely remain below 110 degrees in spite of the higher temperatures, and Heat Advisories likely wont be needed.

AVIATION

(18Z TAFS) Issued at 1235 PM CDT Sat Jun 20 2026

Scattered showers and thunderstorms are forecast to continue this afternoon into the early overnight hours. The probability for impacts are highest at MFE , with convective models and current radar observations supporting training showers and thunderstorms over the next few hours. MVFR ceilings and visibilities will likely occur as storms move over the airfields, and brief IFR conditions can't be ruled out.

Otherwise generally VFR conditions are forecast to continue through the afternoon, with MVFR ceilings developing overnight.

MARINE

Issued at 1235 PM CDT Sat Jun 20 2026

Generally favorable marine conditions are forecast to continue this afternoon. Adverse to hazardous conditions are likely to develop Sunday and Monday with winds increasing to around 20 knots and seas increasing to 5-6 feet. Conditions look to improve by Tuesday, with generally favorable conditions forecast to continue through the remainder of the period.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 83 93 83 94 / 20 10 0 0 HARLINGEN 79 94 80 96 / 30 10 0 0 MCALLEN 81 95 81 98 / 50 10 0 0 RIO GRANDE CITY 78 96 79 100 / 40 10 0 0 SOUTH PADRE ISLAND 84 89 84 89 / 20 10 0 0 BAYVIEW/PORT ISABEL 82 92 82 93 / 20 10 0 0

BRO WATCHES/WARNINGS/ADVISORIES

TX...None. GM...None.