textproduct: Houston/Galveston

KEY MESSAGES

- Tropical Depression Five has developed in the north central Gulf. It is expected to become a Tropical Storm before it makes landfall along the Upper Texas coast on Tuesday.

- Tropical Storm Warnings are in effect for Chambers County, the Bolivar Peninsula, and the adjacent Gulf waters.

- The primary threat is rainfall with widespread 3-5" amounts and isolated 6-9" amounts with the highest totals east of I-45. A Flood Watch is in effect from 1AM Tuesday thru 7AM Wednesday.

- Daily chances for scattered showers/storms continues beyond midweek.

DISCUSSION and TROPICAL

Issued at 111 PM CDT Mon Aug 31 2026

With Tropical Depression (TD) Five bringing imminent impacts to portions of Southeast Texas within the next 24-36 hours, we'll keep the discussion tailored mainly to what's going on and how it may impact you.

TD Five continues to sit off the coast of Louisiana with maximum sustained winds of 35 mph (as of the 1pm advisory). It will continue gradually moving west-northwestward and may become Tropical Storm Edouard as early as later today. Current model guidance continues to point towards a landfall location generally between Sabine Pass and High Island, but this could definitely shift depending on trends. Hurricane Hunter aircraft flew into the disturbance this morning and did not find the data needed to call this a tropical depression/storm as of yet. However, the expectation is for this system to strengthen to a tropical storm by Tuesday morning. As a result, Tropical Storm Warnings are in effect for Chambers County, the Bolivar Peninsula, and the adjacent Gulf waters through Wednesday morning.

While tropical storm force winds are possible (40-50 mph at most based on the higher envelope of intensity guidance) in the warned areas, the main concern from TD Five will be periods of moderate to heavy rainfall. Periods of moderate to heavy rainfall associated with TD Five are expected to begin as early as late tonight and lasting into late Tuesday night/early Wednesday morning. Although if you are in Galveston County, then you already experienced an early round of scattered showers/storms with a little added flavor of tropical moisture. Our latest forecast reflects 3-5 inches with isolated amounts of 6-9 inches. The highest rainfall totals are expected to occur mainly east of I-45. Since we're dealing with a tropical airmass, rainfall rates will exceed 3-4 inches per hour at times in the heaviest downpours. This can lead to flash flooding especially in urban and vulnerable areas (low-lying areas and areas with poor drainage).

The Weather Prediction Center has outlined areas generally east of the Brazos River in a slight risk (level 2 of 4) of excessive rainfall for both Tuesday and Wednesday. A marginal risk (level 1 of 4) of excessive rainfall is in place elsewhere in Southeast Texas for Tuesday and Wednesday. As a result, a Flood Watch has been issued for counties generally along and east of I-45 early Tuesday morning through Wednesday morning. It's important to note that if TD Five is able to sufficiently organize and have the precipitation become more focused around the center, then we could have a scenario where there is a tighter gradient of rainfall amounts. In this scenario, the rainfall amounts would be highly dependent where TD Five makes landfall. So, if it where to become organized and make landfall further east (closer to Sabine Pass), then the rainfall threat would be decreased...and vice versa.

Keeping the rainfall/flooding theme going, we are not currently expecting any widespread or significant issues along area rivers, streams, or bayous. We'll continue to monitor for any potential impacts, especially along the Trinity and San Jacinto River basins. Keep in mind that extended periods of high rainfall rates could cause issues as well, so impacts may be limited right along the axis of the heaviest rainfall.

Since this is a rather small and compact system, we are not expecting storm surge to be a major threat. Strong rip currents, minor coastal flooding, and wave run-up are the most likely outcomes especially along Gulf facing beaches north of San Luis Pass during times of high tide. As a result, a Beach Hazards Statement is in effect from late tonight through Wednesday morning.

This elevated moisture looks to sticks around going into at least Thursday. Increased chances for scattered showers/storms will persist through the end of the work week as a result, especially during the afternoon hours. Some lingering moderate to heavy rainfall is possible on Wednesday with deeper tropical moisture remaining in place for most of the day. Ridging aloft moves back in towards the end of the work week and going into the weekend leading to a return to high temperatures generally in the mid to upper 90s and heat indices peaking above 100 degrees. Daily chances for scattered showers/storms continues into the weekend with the highest chances generally along and south of I-10 along the sea breeze.

Batiste

AVIATION

(18Z TAF Issuance) Issued at 111 PM CDT Mon Aug 31 2026

VFR conditions expected to prevail throughout the day. A moist air mass over our southern TAF sites interacting with the afternoon sea breeze may lead to isolated SH, warranting the use of VCSH. Winds go calm and VRB overnight before ramping back up tomorrow morning, coinciding with the approach of the tropical system. As this system moves onshore along the TX/LA coast, rain bands could bring conditions below MVFR, especially for our coastal sites along and east of I-45. TEMPOs with gusty winds, TSRA, and MVFR cigs/vis were included in the 15Z to 18Z time frame for our southern TAF sites to account for the current window of greatest impacts. GLS has these conditions starting earlier to account for its more coastal position. We will continue to monitor storm trends and their aviation impacts as we get closer to tomorrow.

JMG

MARINE

Issued at 111 PM CDT Mon Aug 31 2026

...A Tropical Storm Warning is in effect for the coastal waters from High Island to Freeport from 0 to 60 NM, including Galveston Bay through Wednesday morning...

Tropical Depression Five is currently off the coast of Louisiana and is slowly moving west-northwest across the northwestern Gulf. This system is expected to move over the Upper Texas coast as a weak Tropical Storm on Tuesday. Given the small size of this system, impacts on navigation should generally remain over the coastal waters from High Island to Freeport, including Galveston Bay. Potential marine impacts include tropical storm-force wind gusts around 30 to 40 knots over the coastal waters, and 15 to 25 knots over Galveston Bay, and building seas of 3 to 5 ft (occasionally higher seas possible). Overall, periods of showers and thunderstorms can be expected this evening into Wednesday morning. Some of these showers could become moderate to heavy at times.

Beach conditions are expected to deteriorate later tonight into at least Wednesday. A Beach Hazards Statement is in effect for all Gulf- facing beaches including Galveston Island and the Bolivar Peninsula. While significant coastal flooding is not anticipated, minor coastal flooding and wave run-up at the beach are possible, especially during times of high tide. The highest probabilities of these conditions are expected to be north of Port Bolivar.

Conditions are expected to improve once the system makes landfall late Tuesday afternoon and evening. However, intermittent scattered thunderstorms are possible throughout the week. Please continue to monitor the latest forecast updates and be prepared.

JM

PRELIMINARY POINT TEMPS/POPS

College Station (CLL) 77 97 75 95 / 10 30 50 60 Houston (IAH) 80 91 78 93 / 10 80 60 70 Galveston (GLS) 81 90 83 91 / 60 70 60 50

HGX WATCHES/WARNINGS/ADVISORIES

TX...Tropical Storm Warning for TXZ214-439.

Flood Watch from 1 AM CDT Tuesday through Wednesday morning for TXZ178-179-199-200-213-214-238-300-313-338-438-439.

Beach Hazards Statement from 1 AM CDT Tuesday through Wednesday morning for TXZ438-439.

GM...Small Craft Advisory until 9 AM CDT Wednesday for GMZ335.

Tropical Storm Warning for GMZ355-375.