textproduct: Houston/Galveston

KEY MESSAGES

- Hot and slightly more humid today with isolated coastal showers/storms.

- Periods of showers and storms are expected each day, peaking from Wednesday to Saturday. Locally heavy rain will be possible.

- Rain chances and increased cloud cover will keep temperatures near seasonal levels through most of the forecast period.

DISCUSSION

Issued at 1134 PM CDT Sun Sep 27 2026

A wet pattern is expected this week, with periods of showers and thunderstorms and a risk of locally heavy rainfall through the upcoming weekend.

Hot weather continues today with a gradual increase in humidity throughout the day. Although the mid to upper level ridge continues to weaken and move out of the region, sufficient subsidence remains to inhibit widespread convection today. However, isolated, diurnally driven showers/storms remain possible. Rain and storm chances increase slightly Tuesday as weak vorticity maxima aloft move over the region. WIll continue with 15% to 25% chance, mainly for the afternoon.

We will continue to monitor the next rainmaker system. A slow-moving mid to upper level longwave trough will continue to move over the western CONUS today, merging with the remnants of what is now Hurricane Polo near Baja California late tonight into Tuesday. Deep Pacific and tropical moisture will be enhanced at the mid to upper levels as the trough moves over the southern Rockies/West Texas. Additionally, a strong southerly influx of humid Gulf airmass will filter across the region, resulting in PWATs in the 2.0 - 2.4 inch range across Southeast Texas through the weekend. These values are in the 90th to 97th percentile of climatology per NAEFS, GEFS and ENS. In terms of standard deviation, these PWAT values are 2 sigma above normal (2-3 near the Brazos Valley), suggesting heavy rainfall that could result in localized flooding. Therefore, showers and thunderstorms will continue to increase on Wednesday, particularly during peak daytime heating due to the combination of deep moisture and mesoscale boundaries such as seabreezes or outflow boundaries from convection developing across central TX.

PWs peak on Thursday and Friday as the main trough digs across the Plains/north-central TX. Global guidance shows a general consensus on timing, but there are still discrepancies regarding the evolution of the system once it approaches our region. Most models suggest a swath of heavy rainfall extending across central Texas, potentially reaching our western counties by Thursday. Confidence in the final location of this axis of convergence and heavy rain is low to moderate. So, it will need to be monitored closely in the coming days, especially for our western zones, including the Brazos Valley. While the general consensus at the moment brings the heaviest band of precipitation west of I-45, we will continue to monitor impacts for higher totals east of I-45 and across the coastal zones through the weekend as PWs remain elevated. Specific details on rainfall amounts remain uncertain. Will continue to monitor trends for any upward or downward adjustments in the coming days. In the meantime, remain weather aware and keep in mind that periods of showers and storms are expected, mainly from Wednesday into the weekend with a risk of heavy rainfall leading to localized flooding.

This system will drag a weak cold front through sometime late Friday or Saturday with rain chances gradually diminishing through the weekend. While the front itself won't have a significant impact on temperatures, precipitation chances and increased cloud cover will keep temperatures near seasonal levels through most of the forecast period.

JM

AVIATION

(18Z TAF Issuance) Issued at 102 PM CDT Mon Sep 28 2026

VFR conditions prevail today despite a few isol showers along the coast. A SE breeze between 5-10kts will continue throughout the day before relaxing overnight. During the sunrise hours a brief period of MVFR VIS and BR is possible within low-lying areas. Tomorrow winds pick back up in the early afternoon with the chance for gusts up to 20kts and continue to remain out of the SE.

CMW

MARINE

Issued at 1134 PM CDT Sun Sep 27 2026

Light onshore winds and low seas will persist through at least Tuesday along with isolated showers and storms. Rain and storm chances will increase after Tuesday as a disturbance moves over the Plains and pushes a frontal boundary off the coast sometime upcoming weekend. Therefore, a daily risk of showers and storms can be expected during the second half of the week, peaking Thursday and Friday. Elevated winds and building seas (up to 7-8ft) are also anticipated. A Small Craft Advisory will likely be needed late Tuesday or Wednesday.

JM

PRELIMINARY POINT TEMPS/POPS

College Station (CLL) 71 96 75 96 / 0 10 10 50 Houston (IAH) 75 93 78 93 / 0 10 20 50 Galveston (GLS) 82 88 83 89 / 0 30 40 40

HGX WATCHES/WARNINGS/ADVISORIES

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