textproduct: Houston/Galveston

KEY MESSAGES

- Periods of showers and thunderstorms are expected through Sunday. Locally heavy rain will be possible and could lead to instances of flash flooding. Best chances for heavy rain is along the coast.

- Cold front pushes through early next week bringing drier air and slightly cooler temperatures.

DISCUSSION

Issued at 1157 PM CDT Fri Oct 2 2026

Scattered showers/storms have mostly waned for the evening, but some of the latest high-res model guidance keeps some isolated activity going through the early half of the night as a weak nocturnal LLJ develops on the northern side of an approaching coastal trough. PW values remain near or above the MAX percentile (~2.3") alongside plenty of instability, so any little source of lift is enough to squeeze out some rainfall...and more of that is to come over the weekend. Synoptically, an upper level cutoff low remains over western TX with an associated surface frontal boundary draped somewhere in southeast TX. Finding the front is essentially on expert mode as it is VERY diffuse and washed out. Going into Saturday, a coastal low/trough in the western Gulf will gradually lifting northward towards the northwestern Gulf coast. Areas generally south of I-10 will be in the middle of the moisture axis from the upper cutoff low (and associated frontal boundary) and the coastal trough/low. So, our attention remains on our coastal areas over the weekend as this two features interact.

The aforementioned frontal boundary is expected to be just offshore on Saturday, but as we talked about before it's hard to tell exactly where it'll be as the winds become easterly from south to north with the approach of the coastal trough/low. PW values remain near the MAX percentile, so a nearby frontal boundary, a coastal trough/low, moisture convergence between the two, and embedded shortwaves in flow aloft will keep the potential for locally heavy rainfall over the weekend...most specifically late Saturday into Sunday mainly along the coast. There two sources of moisture coming together will essentially act as a sponge wringing itself out. The latest suite of model guidance indicates that the highest rainfall totals will occur just off of the coast. Rainfall totals right along the coast are generally anticipated to be in the 1-3" range Saturday through early next week. Areas further inland will likely remain under an inch, but there will be potential for isolated higher amounts both along the coast and further inland...much less likely further inland. Daytime heating, positioning of shortwaves, and a ~25 kt LLJ could lead to a couple of heavier downpours north of I-10 on Saturday afternoon, but most of the heavy rainfall potential lies along the coast.

Keep in mind that the highest rainfall totals are anticipated to occur just 10-20 miles off the coast. That's a relatively small margin of error...a small nudge northward and we could see these higher totals occur further inland. It's worth noting that there's still some deterministic guidance that forms a surface coastal low while others keep an open trough...it remains to be seen which of these scenarios will play out. The previous forecaster also made a great point that water levels will be higher than normal, so heavy downpours during high tide (late evening to overnight hours) would increase the potential for flooding due to the slower drainage. We'll have fairly similar conditions on Sunday, but it will be slightly dependent on if a coastal low manages to develop. If it does, then it may manage to keep most of the rainfall offshore whereas an open trough keeps the door...well open for rainfall to push further inland. Resultingly, WPC has maintained a marginal risk (level 1 of 4) of excessive rainfall for Saturday and Sunday for all of Southeast TX with the main flooding risk being right along the coast.

Coastal rain chances continue on Monday, but Monday will be a bit of a transition day to drier horizons. A cold front is anticipated to push through Monday night/Tuesday morning as an upper level trough dips down into the northeastern/eastern CONUS. We'll get the tail- end of this front, so it won't be a substantial cooldown by any means...but it will be a noticeable one. Low temperatures for most of the work week beyond Monday are expected to range from the low 60s to the low 70s. For those that have been reading the AFDs over the past few nights, I've been throwing probabilities for low temperatures below 70 degrees for the city of Houston. Last night, these probabilities were peaking around 60%. The latest probabilities peak around 70-75% now...those are pretty good odds! High temperatures are expected to be in the 80s through the next work week due to increased rain chances over the weekend followed by the early week cold front.

Drier air behind this front means that we take a break from the rain chances for most of the work week. We're going from PW values above the MAX percentile to closer to the 25th percentile (~1.06") with dew points possibly as low as the upper 40s/low 50s. It's a bit uncertain on exactly when moisture begins to return, but it does appear to be towards the end of the work week. I'm on the border of entering fantasy land, but the tail-end of the work week does look a bit interesting. There is some general agreement in deterministic guidance on an upper low cutting off from a longwave trough near TX towards the end of the work week as another coastal trough/low drifts northward from the Bay of Campeche. What happens beyond that is anyone's guess at this point, but at the very least it looks like rain chances return going into next weekend.

Batiste

AVIATION

(06Z TAF Issuance) Issued at 1157 PM CDT Fri Oct 2 2026

Widespread MVFR cigs expected by morning. Outside of CLL and UTS, VFR conditions will return for all TAF sites by 18Z. A southward moving cold front will lead to persisting MVFR cigs at CLL and UTS, with a drop to IFR cigs likely through the afternoon. This cold front could also result in isolated to scattered showers and thunderstorms for all TAF sites along and north of I-10. A PROB30 was written to highlight the greatest rain chance for these TAF sites between 20 and 00Z. Showers and thunderstorms that develop over these terminals carry the potential to bring sub-VFR cigs/vis and gusty winds. Additionally, a westward moving trough in the Gulf will create persistent showers and thunderstorms near the coast, warranting prevailing -SHRAs and PROB30 -TSRAs for LBX and GLS. Winds through this TAF cycle will primarily be NE at 10-12 kts.

MARINE

Issued at 1157 PM CDT Fri Oct 2 2026

Easterly to northeasterly winds will gradually increase overnight leading to gradually building seas. Caution flags are in effect for the Gulf waters through early Sunday morning then will need to be transitioned to a Small Craft Advisory as winds and seas increase further. In addition to that, water levels will continue to peak around or just above 3.0 ft MLLW during high tide through the weekend, so not enough for coastal flooding hazards but high enough for mariners to take note. Chances for showers/storms persists through the weekend and into midweek as a coastal weather system and frontal boundary interact.

Another cold front will push offshore early next week bringing moderate to strong northeasterly winds peaking around 25 kt sustained and 6-8 ft seas periodically throughout the week. As previously mentioned, shower/storm chances linger over the Gulf waters into midweek.

Batiste

PRELIMINARY POINT TEMPS/POPS

College Station (CLL) 72 84 70 83 / 20 50 20 20 Houston (IAH) 75 88 74 84 / 30 40 40 30 Galveston (GLS) 80 87 78 85 / 40 70 70 60

HGX WATCHES/WARNINGS/ADVISORIES

TX...None. GM...Small Craft Should Exercise Caution from 4 AM CDT Saturday through late Saturday night for GMZ350-355-370-375.