textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1005 PM CDT Sat May 16 2026

Key Messages:

* Persistent near-daily chance of rain, with the greatest threat for precipitation from Thursday through Saturday.

* Above normal daytime highs and overnight lows, with a Moderate to Major heat risk initially, eventually becoming Minor.

* A Moderate to High risk of rip currents at the local beaches.

* Small Craft Should Exercise Caution to Small Craft Advisory conditions for mariners.

DISCUSSION

Issued at 1005 PM CDT Sat May 16 2026

Increasingly unsettled weather will occur during the forecast period. First, deepening and persistent mid-level troughiness over the western United States will allow a 500 mb flow from the southwest to northeast to form and linger over Deep South Texas and the Rio Grande Valley, especially from Sunday through Wednesday. This will allow convection to develop over the neighboring higher terrain of Mexico nearly daily, which will then have the potential to move into the BRO CWFA. Then, on Thursday, the approach of a weak cold front will pool moisture and produce an even greater chance of showers and thunderstorms, which may then persist into Friday and even Saturday.

Temperature-wise, despite the persistent rain chances, well above normal daytime highs and overnight lows are anticipated. A Moderate to Major heat risk will occur almost daily, with the exception of Thursday through Saturday, when a Minor heat risk is forecast due to the more widespread rain chances and associated cloud cover.

Finally, with elevated seas along the Lower Texas Coast, a Moderate to High risk of rip currents is likely for the local beaches.

AVIATION

(12Z TAFS) Issued at 628 AM CDT Sun May 17 2026

An unsettled pattern will continue through the TAF cycle. A cloud deck bringing MVFR ceilings is slowly lifting this morning, returning VFR through the day. Brief bouts of MVFR at all sites are possible through the day with increased moisture. Southeasterly winds become windier through the morning, gusting around 30 knots. Gusty conditions persist through most of the period. MVFR ceilings return overnight.

This evening/tonight, showers and thunderstorms are possible. There is low confidence in convective initiation off the Sierra Madre making it to the Valley, but storms traveling east may impact sites from West to East (MFE, HRL, BRO) overnight. Recent hi-res guidance suggests most likely timing would be 23z through 06z or later. If showers and storms can sustain themselves and cross paths with an airfield, expect lightning and heavy downpours reducing visibility.

MARINE

Issued at 237 AM CDT Sun May 17 2026

UPDATE...Extended Small Craft Advisory (SCA) to all lower TX coastal waters through 14Z Monday. Sunday morning, sustained winds likely drop below 20 kts with occasional gusts to 20-25 kts. A boundary crossing over inland S TX moving east early this morning may bring gusts of 20 to 30 kts. Holding on to SCA through Sunday morning to account for occasional gusts over 20 kts that will become more frequent into the afternoon. There is highest confidence in SCA for the Laguna Madre and nearshore Gulf Waters (out to 20nm) this afternoon, and all waters from midnight Monday onwards. (69)

PREV FORECAST...An enhanced pressure gradient along the Lower Texas Coast will continue to create Small Craft Should Exercise Caution and Small Craft Advisory conditions through the forecast period. The most likely period for Small Craft Advisory conditions, especially in regards to seas, will be in the Monday through Tuesday time frame. (Tomaselli-66)

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 93 81 95 81 / 10 10 10 20 HARLINGEN 94 79 96 79 / 10 10 10 20 MCALLEN 95 80 98 80 / 10 10 10 20 RIO GRANDE CITY 99 79 99 79 / 10 10 10 20 SOUTH PADRE ISLAND 86 81 86 81 / 10 10 10 10 BAYVIEW/PORT ISABEL 91 80 93 80 / 10 10 10 10

BRO WATCHES/WARNINGS/ADVISORIES

TX...High Rip Current Risk from Monday morning through Monday evening for TXZ451-454-455.

GM...Small Craft Advisory until 9 AM CDT Monday for GMZ130-132-135- 150-155-170-175.