textproduct: Houston/Galveston

KEY MESSAGES

- Life-threatening flooding remains possible through Wednesday. An additional 4-10" is possible. Rainfall rates have exceeded 2-5" per hour in some locations. - Trough/Low may drift into the northwest Gulf today. 60% chance of tropical development. Moderate to strong winds could develop over the coastal waters. Cannot rule out gusts possibly to Gale. Tropical funnels and waterspouts will also be possible along the coastline.

- Moderate to high risk of rip currents each day. Elevated tides may lead to minor coastal flooding, especially on Wednesday/Thursday.

DISCUSSION

Issued at 1154 PM CDT Mon Jun 15 2026

Life-threateing Flash Flooding remains possible across portions of SE Texas over the next few days. Currently seeing a short lull in rainfall early today, but anticipate activity to pick back up heading into the daytime. SE Texas remains engulfed within a deep tropical airmass, featuring some of the highest TPWs on recored for this time of the year, around 2.1-2.6 inches. Forecast soundings are still primed with a classic heavy rainfall signature from the deep saturation, thin parcel traces showing modest instability, and a deep warm cloud layer over 16,000ft. Corfidi upshear wind vectors drop to around 10 knots early this morning, with downshear values falling to 10-20 knots during portions of the late morning and early afternoon. Both of which seem to hover around 10-25 knots in the evening into Wednesday. A frontal boundary remains stalled out over the region, with a front-right entrance region of a longwave trough overtop the area as well. We should get an injection of drier air aloft above 700mb this evening, pushing midlevel RH to 60-70% in the Houston area by Wednesday. Drier conditions to the north should result in some mitigation of the flooding risk over those areas, though coastal bound locations, including the Houston area, will remain shrouded within a potent tropical airmass.

Another layer of complexity and uncertainty with this forecast comes from a trough of low pressure, currently situated over the eastern Texas/Mexico boarder. This system is expected to push north/northeast, potentially emerging over the the northwest Gulf/Texas coastal today/early Wednesday. Once over the Gulf waters, this low could deepen and potentially organize into a tropical storm. NHC now gives this system a 60% chance of tropical development within the next 48 hours. Model guidance still has a very mixed handle on this low, with wide variations in timing. Even if this low doesn't develop into a tropical storm, it will still amply heavy rainfall across the Texas coastline.

WPC maintains a Moderate (level 3/4) Risk of Excessive Rainfall over the Texas coastline through early Thursday morning. An additional 4- 10 inches of rainfall are possible through early Thursday morning. Rainfall rates of 2-5"/hr are expected, though these rates could be even higher in spots, as observed on Monday. Life-threating flash flooding will likely occur. Urban and low lying areas will be especially at risk as well. Rises in rivers, creeks and streams will result in minor river flooding at least. Risk of runoff continues to grow as additional rounds of rainfall saturate soils. Once again, Moderate Rainfall Risks are seldom issued, only when there is strong confidence that significant, life-threatening flash flooding could occur. Around 1 out of 5 fatalities from flooding occur on a Moderate risk days. A Flood Watch remains in effect for all of SE Texas until Thursday morning. Make sure to have multiple ways of receiving warnings and remain weather aware! Do not attempt to drive through flooded roadways. TURN AROUND, DONT DROWN!

In addition to rainfall, we will also have to watch out for many other tropical-related hazards with this low pressure. Strong winds will be possible as this system moves across the region. However, there is still a wide amount of spread between models, with winds highly contingent on the strength of the low and whether tropical development occurs or not. Right now, we're anticipating the strongest winds to occur along the coast, especially over the bays and Gulf waters. These winds could reach 20-30 knots with gusts to Gale. Timing the onset of these winds is extremely difficult given the large timing differences, though model guidance shows the most intense winds occuring generally between 4AM to 4PM on Wednesday. With the tropical airmass and the potential for tropical development, SPC also has included a Marginal Risk (level 1/5) SWO over portions of the SE Texas coast through early Thursday morning. Tropical funnels and waterspouts could develop over the waters... could potentially see some of this activity move over land too (contingent on tropical development of course).

Strong currents are expected, with minor coastal flooding possible on Wednesday and Thursday and high tide. A moderate to high risk of rip currents is expected for Gulf-facing beaches as well.

The heavy rainfall threat should decline on Thursday, though a Slight (level 2/4) Risk of Excessive Rainfall will still be in place for lingering rains as the system departs eastward. This risk will diminish into Friday with rain chances decreasing into the weekend as ridging builds over the Gulf.

03

AVIATION

(12Z TAF Issuance) Issued at 629 AM CDT Tue Jun 16 2026

Showers and thunderstorms will increase in coverage this morning, with MVFR to IFR cigs accompanying this activity. The most likely timeframe from storms across all TAF sites is this morning, with a lull in activity expected after 19Z. Cigs will also lift during this lull, with VFR conditions returning during the afternoon and early evening. Another round of storms will develop overnight, along with a low cig (~2500') deck after 06Z. Forecast confidence is low and amendments to the TAF are likely as timing of the rounds of storms becomes clearer.

MARINE

Issued at 1154 PM CDT Mon Jun 15 2026

Additional rounds of widespread showers/storms are expected through the later half of the work week. Light to occasionally moderate onshore winds and seas of 3 to 6 feet are expected to increase tonight into Wednesday as a low moves into the northwestern Gulf. Moderate to strong onshore winds may develop as this system tracks through the waters. While there is a large difference in timing between models, the most intense winds are generally anticipated to occur some time between 4AM to 4PM on Wednesday. Intensity is contingent on tropical development, though winds around 20-30 knots with gusts to Gale will be possible. Seas could reach 7-10 feet, potentially higher at times. Tropical funnels and waterspouts could develop as well. Strong currents are expected. Minor coastal flooding is possible on Wednesday and Thursday around high tide. A moderate to high risk of rip currents is expected for Gulf-facing beaches as well.

Sustained winds should drop under 25 knots around Thursday afternoon, though seas will remain slightly elevated, only dropping below 6 ft by around Friday afternoon/evening.

03

TROPICAL

Issued at 1154 PM CDT Mon Jun 15 2026

A trough of low pressure currently over the eastern Texas/Mexico boarder is expected to drift north-northeastward throughout today. Spaghetti plots for Invest 90L all support this motion, with the system favored to move into northwestern Gulf along the Texas coast today. Once over the waters, this low could deepen and potentially organize into a tropical storm. Convection within this low has flared up overnight, showing more promising signs of TC development. With this in mind, NHC now gives this system a 60% chance of tropical development within the next 48 hours. Regardless of tropical development, heavy rainfall is expected and dangerous marine conditions are possible. Rainfall rates are expected to be around 2-5"/hr, possibly higher, especially along the coast. Moderate to strong winds could develop across the waters and bays early Wednesday with gusts to gale. Tropical funnels and waterspouts could spin up at times throughout Wednesday. Minor coastal flooding could occur as well.

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PRELIMINARY POINT TEMPS/POPS

College Station (CLL) 84 73 88 76 / 50 10 20 0 Houston (IAH) 82 75 88 77 / 90 40 60 40 Galveston (GLS) 85 80 88 83 / 100 80 70 50

HGX WATCHES/WARNINGS/ADVISORIES

TX...Flood Watch through Thursday morning for TXZ163-164-176>179- 195>200-210>214-226-227-235>238-300-313-335>338-436>439.

GM...Small Craft Should Exercise Caution until 7 AM CDT this morning for GMZ330-335-350-355-370-375.