textproduct: Houston/Galveston

KEY MESSAGES

- A wet, muggy weather pattern will continue through the rest of the week across southeast Texas, bringing temperatures slightly below normal (upper 80s) for this time of the year.

- Rain chances will continue through the week with 3-6 inch rainfall totals more likely (50-60% chance of 3+ inches) later this week and through the weekend.

- The threat of hazardous rip currents remains through at least midweek before marine hazards transition to thunderstorm-driven waves.

DISCUSSION

Issued at 104 AM CDT Tue May 19 2026

Through most of the workweek into the weekend, the broader-scale synoptic pattern of troughing across the Intermountain West and ridging across the southeast U.S. will retain its position over the CONUS with some amplifying evolutions/permutations to the local southwesterly flows (and subtropical jet) aloft. As the longwave trough delivers multiple ejections into the Great Plains, it will maintain a moisture-rich southwesterly flow aloft (PWATs near 2 inches, well above the 75% percentile of climatology). This, combined with the advection of embedded vorticity maxima and lift from an attendant frontal boundary, sets the stage for multiple rounds of efficient rainfall producing convection (some storms could produce 3 to 4 inches of rain per hour).

Forecast uncertainty remains with the expected evolution of convective systems as they approach and proceed through southeast Texas, however, the congruency that is emerging among short-term model solutions at the moment favors MCS propagation. The first in multiple rounds of MCSs is expected later tonight into the overnight hours, while more concentrated convective rounds are expected on Thursday and later this week. The cumulative concern is for where the soils are primed the most from antecedent rains by Friday and subsequent Flood Watch issuance can't be ruled out at this time. Long-range guidance continues the wet trend into early next week with Day 1-7 QPF values of 5-7 inches becoming likely.

Cassel

AVIATION

(12Z TAF Issuance) Issued at 627 AM CDT Tue May 19 2026

SHRA and isolated TSRA over the area will dissipate over the next few hours. MVFR cigs expected to trend VFR by the afternoon, with SE winds becoming more ESE later in the day. We still anticipate a line of SHRA/TSRA to move into the area from the north and west this evening / overnight. However, confidence in the forecast (especially regarding TSRA timing and severity) is quite low. In addition, the wind direction/speed forecast is uncertain tonight into Wednesday morning. The primary concern from TSRA will be strong gusty winds.

MARINE

Issued at 1242 AM CDT Tue May 19 2026

Gusty southeast flow and enhanced Gulf seas will continue into Tuesday. However, the primary weather concern will be the potential for strong thunderstorms overnight tonight and into Tuesday. Thunderstorm winds could easily exceed gale force and result in locally higher seas. It is important to note that thunderstorm related winds can be felt tens of miles away from the storm. Thunderstorms can also result in sudden changes in wind direction.

As for the rest of the week, expect generally light to moderate south to southeast winds and 3-4 ft seas. There will be a continued daily risk of showers and thunderstorms, with locally higher winds and seas in the vicinity of any thunderstorm.

HYDROLOGY

Issued at 344 PM CDT Mon May 18 2026

Anticipating multiple rounds of moderate to heavy rainfall Tuesday through at least Saturday. These rounds are expected to mostly be in the form of Mesoscale Convective Systems (MCS's). The exact timing of these storms can be a bit tricky as mesoscale factors play a key role (hence the name), but we anticipate the first round to come late Tuesday. With PW values exceeding the 90th percentile (~1.7-2.1"), rainfall rates will likely exceed 3-4"/hr in the heaviest downpours. While these lines of storms are typically progressive, the rainfall received early in the week is expected to prime the soils for rounds later in the week. Saturated soils leads to a quicker transition to runoff which brings an increased risk of flooding. We continue to anticipate widespread rainfall totals of 5-7" with isolated higher amounts. The highest rainfall totals are still expected to occur north of I-10.

This rainfall will generate runoff and cause rises on area rivers and watersheds. Action to minor stage flooding is the most likely outcome, but cannot entirely rule out moderate to isolated major stage flooding depending on where the most rainfall accumulates. Remember that you can monitor updated river forecasts via the NWS NWPS webpage (https://water.noaa.gov/).

Landry-Guyton

PRELIMINARY POINT TEMPS/POPS

College Station (CLL) 89 72 83 72 / 40 70 70 60 Houston (IAH) 89 76 86 75 / 40 60 60 40 Galveston (GLS) 86 79 85 79 / 40 50 30 20

HGX WATCHES/WARNINGS/ADVISORIES

TX...High Rip Current Risk through this evening for TXZ436>439.

GM...Small Craft Advisory until 9 AM CDT this morning for GMZ330-335- 350-355.

Small Craft Advisory until 7 AM CDT Wednesday for GMZ370-375.