textproduct: Houston/Galveston

KEY MESSAGES

- Closely monitoring weather for the 250th Independence Day with increased heat stress expected.

- Hot Weather continues with peak heat index values reaching 100- 110F (38-43C).

- Daily rain chances. Light streamer showers possible in the morning, then scatters/isolated storms during the afternoon.

DISCUSSION

Issued at 315 PM CDT Thu Jul 2 2026

The broader synoptic pattern has not changed significantly across SE Texas. A robust ridge is still situated across the Tennessee-Ohio Valley/Mid Atlantic region today, with midlevel heights upwards of 596-597 dam (around the 99th-100th climate percentile). On Friday, this ridge will shift eastward and weaken, with heights decreasing and slowly meshing into the broader tropical high to the south on Saturday, which amplifies to around 591-592 dam this weekend. Though, southeast Texas is still expected to remain on the peripheral of both these ridges, with midlevel heights remaining around 590-593 dam (~70-90th climate percentile) and 850mb temperatures around 18-21C (~70-80th climate percentile). With this persistent onshore flow and WAA we'll continue to see hot weather across SE Texas for the foreseeable future. Rain chances will vary from day to day, though, with some weak impulses passing aloft, no strong capping and onshore theta e advection, there can certainly be some occasional showers and thunderstorms. This is most likely to manifest as spotty streamer showers over the Gulf early in the morning, then as some scattered/isolated showers and thunderstorms in afternoon near the coast along the sea breeze. As noted yesterday, low level lapse rates are also very steep, nearly dry adiabatic at 8-9 DegC/km, so any pop up storms could produce some modest downbursts at least, though not particularly strong.

In general, hot weather continues with highs in the 90s and triple digit heat indices ranging from 100-110F (38-43C). WBGT values indicate that heat stress on the human body will be high, possibly reaching extreme in spots during the afternoon. There will be daily chances of rain, possibly as light streamer showers over the Gulf/Coast in the morning and maybe some pop-up showers/storms in the afternoon, especially along the sea breeze.

Independence Day is this Saturday, and as many of you have likely heard, it will be the Semiquincentennial (250th anniversary) of the founding of the United States of America. Outdoor events and celebrations for this milestone will likely draw in massive crowds, thus extra care was put into the July 4th forecast, specifically with regards to heat stress.

Heat index values these last few days have generally remained under 108, mainly as a result of modest afternoon mixing lowering humidity. The NBM generally struggles with this mixing, so I've adjusted dewpoints down slightly in the afternoon, generally keeping to the higher-end observed values from our ASOS stations (as to not mix out too much). Model guidance has been pinging temps to be generally higher on Saturday. Yesterday NBM was a tad too cool in spots, so I've increase highs slightly to compensate, closer to around the 75th percentile in the NBM. The pressure gradient does weaken on Saturday, and thus winds become very calm in the morning through the early afternoon. Timing/intensity of the sea breeze can be tricky to pin down on day 3 (since it falls beyond the cams), thus to error on the side of caution, I mixed in some NBM 10th percentile to simulate a slower & weaker afternoon sea breeze. Cloud cover is another parameter that can be difficult to narrow down beyond the 48 hour high-res window, though this current synoptic pattern has tended to produce few-scattered q-fields in the afternoon. Model vorticity and UVV are both especially weak on Saturday, in addition to NBM guidance trending lower on PoPs for the 4th as well. With this in mind, I've opted to lower cloud cover slightly (in addition to capping PoPs around 10%).

The culmination of all these changes still produces highs in the 90s and heat indices around 101-109F for the 250th Independence Day. The resulting Wet Bulb Globe Temperature values are forecasted around 86- 91 between 12PM-6PM. Resulting heat stress on the human body is forecasted to be high (level 3/4), reaching extreme (level 4/4) in a few isolated spots. Extra emphasis on the *isolated spots* portion, as the spatial & temporal scale of those extreme values is small (mostly within the Houston metro between 2-4PM). In laymens terms, it'll feel a warmer than the typical summer days as of recent, though not dramatically different.

Despite more conservative heat projections, the current forecast doesn't suggest a need for heat headlines at this moment, though that could change with the next forecast cycle. Regardless of whether or not a heat advisory is issued, it would still be wise to practice heat safety. If you plan to spend the day outdoors, make sure you wear light cloths, apply sunscreen and stay hydrated by drinking plenty of water. Heat is the #1 weather-related killer in the U.S. each year, and often people greatly underestimate it's danger. Even if the heat isn't advisory-strength, more people outside means that more cases of heat illnesses will likely emerge as a result.

03

AVIATION

(12Z TAF Issuance) Issued at 622 AM CDT Thu Jul 2 2026

VFR conditions and light winds are currently in place across all terminals. Streamer shower activity this morning may result in brief MVFR ceilings for the coastal locations. Isolated to scattered showers and thunderstorms are likely to develop late this morning along the coast and move inland through the day. Any convection that does develop should wane around 00Z. Will maintain the current PROB30 groups for TSRA with this TAF cycle. Have introduced a TEMPO group Friday morning to account for a medium chance (per the latest HREF probs) for MVFR ceilings from 09-12Z.

MARINE

Issued at 315 PM CDT Thu Jul 2 2026

Light S/SE winds around 10 knots and calm seas of 1 to 3 feet are expected throughout the next several days. Light streamer showers could develop over the Gulf waters each morning. Isolated to scattered thunderstorms could develop along the sea breeze in the afternoon near the coastline and bays.

03

PRELIMINARY POINT TEMPS/POPS

College Station (CLL) 76 95 77 96 / 10 0 0 0 Houston (IAH) 77 95 78 96 / 20 10 10 10 Galveston (GLS) 83 90 82 90 / 20 20 10 10

HGX WATCHES/WARNINGS/ADVISORIES

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