textproduct: Houston/Galveston

KEY MESSAGES

- Dangerous heat will continue through the weekend, with a Heat Advisory in effect through Saturday evening. Limited cooling overnight will exacerbate the heat.

- Scattered showers and thunderstorms are possible on Friday and Saturday, with the potential for locally heavy rainfall. There is a level 2 out of 4 risk for excessive rainfall Friday and Friday night. A few strong storms with gusty wind cannot be ruled out.

- A high risk of strong rip currents is expected through the weekend.

DISCUSSION

Issued at 1249 AM CDT Fri Jun 19 2026

We remain in an oppressively warm and humid regime as shortwave upper ridging has built in along the western Gulf Coast. In fact, the high heat and humidity resulted in the development of haze yesterday afternoon, and that haze has persisted into the overnight hours across much of the area. While the likelihood of warm and humid conditions remains high today, we will introduce a potential fly in the ointment over the next few days that might limit heat stress in some areas, at least periodically. A shortwave tracking from the Red River Valley toward the Central Gulf Coast will bring a chance for showers and thunderstorms through the weekend, with rain and storm chances coming in rounds. The first such round could arrive by this afternoon as either upstream convection moves southeastward into the area or remnant outflow from upstream convection helps to kick off new development over our area. Because of the mesoscale nature of this activity, forecast confidence in timing and location details remains low for now. However, at this stage there is some indication that this afternoon through Saturday morning will be the general time frame with highest rain chances.

While very high rainfall totals are not expected to be widespread, both the 00z HREF and REFS depict meaningful probabilities for much more localized rainfall amounts over 5" in a few areas through early Saturday. Given the moisture rich environment, with forecast PW rising above 2 in at times, and the saturated soil conditions from rainfall over the past few days, flash flooding will be a possibility if these rainfall totals materialize through early Saturday. WPC is maintaining a slight ERO across most of our area. Additionally, while deep layer shear to support organized storms will be weak, sufficient instability will be possible that we cannot rule out a few stronger storms capable of damaging wind gusts.

As mentioned before, outside of interference from clouds and rain, heat stress will remain elevated with potential for heat indices in the 108-112F (42-44C) range. A Heat Advisory remains in effect through early Saturday evening. Adjustments to timing may be needed depending on downstream impacts from clouds/precip.

Rain chances will trend down again early next week as mid level ridging restrengthens along the northwestern Gulf coast. High temps will trend back up toward the mid 90s (34-36C) and heat indices in the triple digits (38C+) will remain possible. Better daytime mixing may limit dewpoints enough to limit peak heat indices somewhat, but additional heat products cannot be ruled out.

AVIATION

(12Z TAF Issuance) Issued at 619 AM CDT Fri Jun 19 2026

Predominantly MVFR conditions early today driven by CIGs (though some fog/haze) with isolated pockets of IFR FLs. FLs should improve to VFR with daytime heating, though slightly slower in spots compared to yesterday. A MCS/complex of thunderstorms has developed over the DFW/San Angelo Area early this morning. Forecast models project this convection to track southeasterly throughout the day, though are split on timing and intensity by the time it reaches SE Texas. Upgraded to TEMPO groups for TSMS for the northern tier of TAF sites and maintained PROB30s to the south. Should see a lull in convection during the evening hours with CIGs/fog starting to fill in. Another potential round of showers/storms could occur early Saturday morning with a passing disturbance aloft, though forecast uncertainty is high by this point.

03

MARINE

Issued at 1249 AM CDT Fri Jun 19 2026

Moderate south to southeasterly winds will begin to weaken through this morning, though seas up to 7ft remain possible over the offshore waters through around daybreak. Isolated to scattered thunderstorms are possible tonight through Saturday. Otherwise, light to moderate south to southeasterly winds will persist through the weekend, with seas generally remaining below 6 feet.

PRELIMINARY POINT TEMPS/POPS

College Station (CLL) 93 77 90 77 / 40 40 40 10 Houston (IAH) 93 80 92 79 / 30 30 40 20 Galveston (GLS) 90 83 89 83 / 0 20 20 20

HGX WATCHES/WARNINGS/ADVISORIES

TX...Heat Advisory until 10 PM CDT Saturday for TXZ163-164-176>179- 195>200-210>214-226-227-235>238-300-313-335>338-436>439.

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

GM...Small Craft Should Exercise Caution until 7 AM CDT this morning for GMZ330-335-350-355.

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