textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1259 PM CDT Thu Jul 23 2026

- A Heat Advisory is in effect today for Zapata and Starr Counties, where heat indices could exceed 111 degrees is conditions stay relatively clear. A Special Weather Statement for heat is also in effect for Jim Hogg, Brooks, and Kenedy Counties where heat indices could approach 111 degrees.

- All of Deep South Texas (excepting coastal areas) is in a Major (level 3 of 4) Heat Risk today and a Moderate (level 2 of 4) Heat Risk tomorrow and Saturday. Heat Risk will continue into next week.

- There is a Marginal (level 1 of 4) Risk of Excessive Rainfall today for most of Deep South Texas, along with a Marginal (Level 1 of 5) Risk of Severe Weather this afternoon/evening for all of Deep South Texas.

- After today's rain chances, conditions should be hot and precipitation free this weekend through the middle of next week.

- A Moderate Risk of Rip Currents begins tonight and continues into tomorrow.

DISCUSSION

Issued at 1259 PM CDT Thu Jul 23 2026

The same mid-level wind shear that is weakening Tropical Storm Bertha's center of low pressure to the north is also pushing a wave of moisture along with associated convection further south- southeast into Deep South Texas. There are ongoing showers and thunderstorms that have come ashore due to an ongoing mesoscale convection system over the Gulf, and more is expected later this afternoon into the overnight hours. There is a 30-50% chance of showers and thunderstorms today for all of Deep South Texas, and a 50-80% chance for the Northern and Western Ranchlands tonight, with lower chances in the SE portion of the CWA.

The Weather Prediction Center has placed most of Deep South Texas (excepting the lowest portion of the Rio Grande Valley) under a Marginal Risk of Excessive Rainfall for today. Some areas could see between 1 and 2 inches with locally higher amounts between 2 and 4 inches. Current guidance indicates that the Northern and Western Ranchlands should see the most precipitation, and much of this is expected to occur this evening into the overnight hours as the bulk of the showers and thunderstorms move inland. Isolated flash flooding is possible in areas that receive higher rainfall amounts in a shorter period of time. However, most of the rain received is expected to be beneficial.

In addition, all of Deep South Texas is under a Marginal Risk of severe thunderstorms this afternoon into the evening. Scattered clustered thunderstorms are expected to accompany the precipitation that moves onshore from the Gulf, and there could be pockets of severe thunderstorm activity within these clusters. The primary threat with these storms would be damaging winds with the potential for downbursts. The threat should end by tomorrow morning as the convection pushes off to the west. Hot and dry conditions will follow tomorrow and prevail through the remainder of the forecast period.

Heat is also a concern this afternoon and will continue through the middle of next week. A Heat Advisory is in effect for Zapata and Starr Counties today from 1 PM to 7 PM CDT. Heat indices could exceed 111 degrees today in these areas, but this threat is conditional on cloud cover. If these counties stay relatively clear through mid-afternoon, it is more likely that Heat Advisory criteria will be met. However, ongoing convection in the region could push cloud tops further west, which could help cool temperatures a few degrees and keep these areas out of Heat Advisory criteria. If it looks like we may not reach Heat Advisory criteria due to cirrus cover, the Heat Advisory may be cancelled this afternoon.

Regardless, all of Deep South Texas remains under a Major (level 3 of 4) Heat Risk today due to elevated temperatures and humidity. A Special Weather Statement has also been issued for Jim Hogg, Brooks, and Kenedy Counties, as heat indices in these counties may also approach but not reach Heat Advisory Criteria.

Due to ongoing upper level ridging over Gulf, the heat will remain a concern this weekend into next week. to Moderate (level 2 of 4) Heat Risk is expected tomorrow through the weekend for most of Deep South Texas, but urban areas in the Lower Rio Grande Valley could see Major Heat Risk. The heat will continue through the middle of next week where some areas in the Lower Rio Grande Valley could even see Extreme Heat Risk, with additional Heat Advisories possibly needed.

Though the center of circulation for Tropical Storm Bertha is well to the north, There will be some potential beach hazards due to elevated swell. Some slightly higher surf is expected, along with a Moderate Risk of Rip Currents that begins tonight and continues into tomorrow.

AVIATION

(18Z TAFS) Issued at 1259 PM CDT Thu Jul 23 2026

VFR conditions with the chance of rain prevails over the next few hours as convection makes its way onshore from the Gulf. This could temporarily deteriorate conditions in the vicinity of any showers. Otherwise, conditions will become increasingly cloudy over the TAF period. Rain is possible (especially at MFE) in the overnight hours. Southeasterly winds are expected throughout the entire TAF period and could be gusty at times this afternoon.

MARINE

Issued at 1259 PM CDT Thu Jul 23 2026

SCEC conditions are possible especially on the Gulf Waters this afternoon into this evening as convection moves over the Gulf and comes ashore. There could also be some stronger thunderstorms within this cluster of convection that could further deteriorate conditions. Conditions should improve tomorrow into the weekend and stay overall favorable through the middle of next week, with the potential for some intermittent SCEC over the Bay early next week.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 81 96 80 96 / 10 0 0 0 HARLINGEN 78 98 77 98 / 30 0 0 0 MCALLEN 81 101 79 102 / 60 0 0 0 RIO GRANDE CITY 79 101 77 101 / 90 10 0 0 SOUTH PADRE ISLAND 81 88 81 88 / 10 0 0 0 BAYVIEW/PORT ISABEL 79 94 79 93 / 20 0 0 0

BRO WATCHES/WARNINGS/ADVISORIES

TX...Heat Advisory until 7 PM CDT this evening for TXZ248-252.

GM...None.