textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 102 PM CDT Sat Apr 11 2026

Key Messages:

* Isolated to scattered sprinkles/rain showers ongoing over parts of the area will continue through this afternoon before waning later this evening/tonight.

* Showers and thunderstorms (perhaps strong the severe) could develop late Sunday afternoon and persist through Sunday night; low-medium (30-40%) chances. * There is a Slight Risk (Level 2 of 5) for severe thunderstorms over the northwestern sections of the area Sunday PM; Marginal Risk (Level 1 of 5) elsewhere. Damaging winds, large hail, an isolated tornado, and heavy rainfall/localized flooding are the primary threats.

* The best timing for showers and thunderstorms on Sunday will be between 6PM CDT Sunday to 3AM CDT Monday.

* Warmer than normal temperatures, dry, and at times breezy conditions will prevail next week (Mon-Fri).

* Adverse (Small Craft Exercise Caution) marine conditions will continue through next week.

DISCUSSION

Issued at 102 PM CDT Sat Apr 11 2026

The main weather concern during the forecast period will continue to be on the risks for showers and thunderstorms this weekend, particularly Sunday evening/Sunday night. Otherwise, mainly dry, normal to warmer than normal temperatures, and at times breezy conditions will prevail through the forecast period.

We start off the forecast period today, where the region sits under an at times active southwest flow aloft regime and on the leeward side of a potent upper low over the western U.S. Latest GOES-19 visible satellite imagery and radar scans reveal a SCT-OVC deck of stratocumulus clouds from overnight's mist/low stratus in place over the region with some diurnal sprinkles/rain showers around.

Forecast models continue to depict a couple rounds of shortwaves (some of which can be rather vigorous) moving over the region. The first round will come this afternoon into tonight and another round later in the day on Sunday into Sunday night. As sfc heating continues to increase during the day today, instability values will also increase. This combined with nearby shortwaves will help to maintain the sprinkles/showers ongoing already. There is an outside chance for a thunderstorm or two developing this afternoon into this evening. Limiting factors will be weak CAPE and bulk shear values, despite solid mid-level lapse rates. Given the observations and recent trends, and after collaboration with neighboring offices, have decided to bump up PoPs today across the region. That said, have isolated chances or low (20-30%) chances for showers and thunderstorms developing later this afternoon.

Otherwise, expect for dry conditions with breezy southerly winds to prevail through today with high temperatures topping out in the mid to upper 80s. For tonight, outside of the risk for any lingering showers, expect for a quiet and warm night with overnight low temperatures in the low to mid 70s. There could be some mist/fog/low stratus that develops overnight due to the combination of ample low level moisture and some radiational cooling.

As mentioned, better chances for showers and thunderstorms will exist Sunday, specifically late Sunday afternoon/Sunday evening persisting through Sunday night. CAM models continue to depict a more robust shortwave moving overhead Sunday evening. This combined with strong CAPE values and still solid mid-level lapse rates could present better opportunities for showers and thunderstorms Sunday evening/night. The RRFS model continue to depict showers and thunderstorms developing off the Sierra Madre Oriental Sunday afternoon and translating east-northeastward into our CWA Sunday evening/night. The best timeframe for these thunderstorms to develop will be between the hours of 6pm CDT Sunday to 3am CDT Monday. Again, based off recent model and forecast trends, and after collaboration with neighboring offices, have decided to bump up PoPs for Sunday. That said, have low to medium (30-40%) chances for showers and thunderstorms developing Sunday evening/night.

The Storm Prediction Center (SPC) has maintained a Slight Risk (Level 2 of 5)for severe thunderstorms over the northwestern sections of our CWA including the northwestern half of Zapata County and extreme northwest Jim Hogg County with the remainder of Deep South Texas under a Marginal Risk (Level 1 of 5) for severe thunderstorms. Damaging winds and large hail will be the primary threats. Can't rule out an isolated tornado. While we currently are not under an risk for excessive rainfall, heavy rain and localized flooding is possible Sunday evening/night due to the combination of high atmospheric moisture content and the likelihood of slow moving storms. Precipitable water (PWAT) values are expected to be between 1.5-2 inches, some +1 to +3 STDEVs above normal. We will continue to monitor thunderstorm, severe weather, and heavy rainfall/flooding trends. Otherwise, expect for warm and dry conditions to continue with high temperatures in the mid 80s near the coast to near 90F degrees west.

Rain-free, warmer than normal, and at times breezy conditions will prevail Monday through Friday of next week. High temperatures are progged to range between the upper 80s to mid 90s. Overnight low temps are expected to range between the upper 60s/low 70s over the Northern Ranchlands to the low to mid 70s along the Rio Grande Valley.

AVIATION

(18Z TAFS) Issued at 102 PM CDT Sat Apr 11 2026

Through 18z Sunday....As of 12:20 PM CDT, GOES-19 visible satellite imagery and sfc observations revealed a SCT-OVC stratocumulus deck of VFR-MVFR clouds overhead with cloud bases ranging between 2,000-4,000 feet AGL and unrestricted visibilities. There are a few rain showers out there this afternoon as well.

Through today, expect for mainly VFR conditions to prevail with some MVFR clouds around. Diurnal driven rain showers will persist through this afternoon before decreasing in coverage later this evening/tonight. Have VCSH for the terminals through this afternoon to acknowledge the risks for some sprinkles/showers. Tonight, ample low level moisture could support in the return of low stratus (MVFR- IFR). MVFR cigs could persist through the morning hours on Sunday.

South-southeast winds 10-20 kts with gusts as high as 25-30 kts are expected to prevail through the 18z TAF period.

MARINE

Issued at 102 PM CDT Sat Apr 11 2026

Adverse (Small Craft Exercise Caution) marine conditons will prevail through next week thanks to an enhanced pressure gradient resulting in breezy winds out of the south and building wave heights. Small Craft Exercise Caution headlines will be needed each afternoon through next week.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 74 85 73 86 / 10 30 30 0 HARLINGEN 70 87 69 89 / 10 30 30 0 MCALLEN 74 89 75 90 / 10 40 40 0 RIO GRANDE CITY 73 90 72 90 / 10 40 40 10 SOUTH PADRE ISLAND 74 78 73 79 / 10 30 30 0 BAYVIEW/PORT ISABEL 71 83 71 84 / 10 30 30 0

BRO WATCHES/WARNINGS/ADVISORIES

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