textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 119 PM CDT Sun May 3 2026

Key Messages:

* Warmth/heat builds through Wednesday with Wednesday projected to be the hottest day of the week.

* Widespread Moderate (Level 2 of 4) Heat Risk is expected on Tuesday and Wednesday with pockets of Major (Level 3 of 4) Heat Risk on Wednesday; heat indices are expected to range between 100- 110F degrees Tuesday and Wednesday. * Day-to-day or near day-to-day chances for showers and thunderstorms are possible Thursday through next Sunday as the weather pattern looks to become wetter or more active.

DISCUSSION

Issued at 119 PM CDT Sun May 3 2026

The main weather concern during the forecast period across Deep South Texas and the Rio Grande Valley will be focused on the increased prospects for showers and thunderstorms Thursday this week through at least next weekend as there are increasing signs that the weather pattern during the early to middle parts of May could become active/wetter/stormier.

Today through Wednesday night (Rain-free with Building Heat Risk)...

Rain-free weather conditions are expected to persist today through Wednesday night, courtesy of a sfc high pressure system in place and a ridge axis passing overhead from west to east. During this timeframe or through Wednesday, the warmth/heat will steadily strengthen each day. This warming trend through Wednesday will be as a byproduct of the local forecast area placed on the northern fringes of a strengthening 588-591 dam heat ridge. Temperature anomalies during this warming trend will go from below normal levels today to above normal levels by Tuesday and Wednesday. High temps will go from the low to mid 80s this afternoon to the upper 80s on Monday to the low to mid 90s on Tuesday to finally the mid to upper 90s on Wednesday.

Heat indices ranging between 100-110F degrees (highest along the Upper Valley) will score widespread Moderate (Level 2 of 4) Heat Risk on Tuesday. Widespread heat indices across Deep South Texas and the Rio Grande Valley ranging between 105-110F degrees will score widespread Moderate (Level 2 of 4) Heat Risk with pockets of Major (Level 3 of 4) Heat Risk on Wednesday. Overnight low temps tonight are progged to be in the 60s across Deep South Texas. Monday night through Wednesday night, overnight lows are progged to be in the 70s. On Tuesday, an enhanced sfc pressure gradient will result in a breezy day with southerly winds 20-30 mph and gusts between 30-40 mph.

Thursday through Next Sunday (An active, wetter, stormier pattern could develop)...

Attention turns to the potential for showers and thunderstorms, and the chance for some much-needed rainfall that could further address the remaining drought conditions across the region Thursday through at least next weekend.

Multiple global computer models and AI/ML ensembles are depicting a split-flow jet stream regime across the contiguous U.S. this week through next weekend. This large-scale pattern will feature an anomalously strong mid-upper low/trough over the Southwestern U.S. This trough will help to enhance or activate the southern branch jet stream or sub-tropical jet over northern Mexico and all of Texas including our local forecast area Thursday through next weekend. Several perturbations/impulses will track overhead along this southern branch jet stream. Meanwhile, during this timeframe (Thursday through next weekend), southerly winds will help to increase deep tropical moisture from the Gulf. Global forecast models are indicating precipitable water (PWAT) values rising from 1-1.5 inches today through Wednesday to 1.5-2.3 inches Thursday through next weekend. Instability values will also increase alongside increased moisture advection. Finally, a cold front is expected to approach the region Thursday into Friday before stalling or washing out to our south.

Multiple mid-upper energies/shortwaves, some of which can be vigorous, combined with increased moisture and instability values, and an approaching cold front could potentially result in an active/wet/stormy weather pattern taking shape with day-to-day or near day-to-day chances for showers and thunderstorms developing over Deep South Texas and the Rio Grande Valley Thursday through at least next weekend. Currently, we have low-medium (20-50%) chances for showers and thunderstorms Thursday through next Sunday with some of the greater probabilities Thursday through Friday and the lower probabilities Saturday and Sunday.

We will continue to monitor forecast model and probability for precipitation (PoP) trends in the days ahead. We currently aren't outlooked under any risk for severe weather or excessive rainfall, but that could change. Given the elevated atmospheric moisture content that will be in place, any showers or thunderstorms that develop will have the capabilities of producing heavy rainfall, which at the very least can create instances of ponding and localized flooding.

The Climate Prediction Center (CPC) has a medium (50-60%) chance for a wetter than normal pattern in it's 6-10 day (May 8-12) and a medium (40-50%) chance for a wetter than normal pattern in it's 8-14 day (May 10-16) timeframe, which suggest that an active/stormier pattern could persist from early May (later this week) through the middle parts of May.

Despite the recent green up and improved drought conditions from previous rains in April, additional rainfall is needed and will be beneficial in addressing the remaining drought conditions over the region. As of April 28th, the U.S. Drought Monitor had D1 (Moderate Drought) to D3 (Extreme Drought) designations over Deep South Texas with about 59% of the region under a D2 (Severe Drought), 2% under a D3 (Extreme Drought), and the remaining under a D1 (Moderate Drought).

Temperatures Thursday through next Sunday will run normal to slightly above normal levels, but slightly cooler than Wednesday, due to the weakening cool front and the potential for showers and thunderstorms each day. High temperatures Thursday through next Sunday are progged to climb into the upper 80s to lower 90s. Overnight low temperatures will remain in the 70s each night.

AVIATION

(18Z TAFS) Issued at 119 PM CDT Sun May 3 2026

Through 18z Monday....VFR conditions are expected to prevail through the 18z TAF period.

Winds will generally be out of the northeast through today with speeds between 5-12 kts. Occasional gusts between 15-20 kts is possible this afternoon. On Monday, winds will shift out of the southeast with speeds between 10-15 kts. Winds could gusts as high as 20-25 kts.

MARINE

Issued at 119 PM CDT Sun May 3 2026

Generally favorable marine conditions are expected through next Sunday with light to moderate winds and moderate seas with wave heights mainly between 3-4 feet. Thursday-Thursday night, adverse marine conditions could develop and a Small Craft Exercise Caution (SCEC) conditions are possible in response to a cool front.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 68 84 75 89 / 0 0 0 0 HARLINGEN 63 87 71 92 / 0 0 0 0 MCALLEN 67 88 75 94 / 0 0 0 0 RIO GRANDE CITY 65 88 72 97 / 0 0 0 0 SOUTH PADRE ISLAND 73 80 76 83 / 0 0 0 0 BAYVIEW/PORT ISABEL 68 84 73 88 / 0 0 0 0

BRO WATCHES/WARNINGS/ADVISORIES

TX...High Rip Current Risk until 7 PM CDT this evening for TXZ451-454- 455.

GM...None.