textproduct: Houston/Galveston

KEY MESSAGES

- Rain chances increase tonight into Wednesday in association with a weak surface trough and some upper disturbances.

- Arctic Front should sag into the region Friday and Friday night, bringing various winter hazards over the weekend: - Some prolonged temperatures and potential hard freezes. - Low Wind Chill Values, potentially between 7-20 degrees. - Risk of Freezing Rain, Sleet/Ice Pellets - Hazardous marine conditions.

- Residents are encouraged to winterize their home during the work week prior to the cold weather arrival.

DISCUSSION

Issued at 136 PM CST Tue Jan 20 2026

Today through Thursday:

A weak front remains stalled across the area today. A few showers have developed in the vicinity of Matagorda Bay in a low-level confluence zone and have raised PoPs in that area for the rest of the day. Tonight and tomorrow a couple shortwaves in the northern stream will have a glancing influence on our northern counties, while some weak southern stream disturbances have a glancing influence on our southern counties with overall cyclonic flow aloft across the forecast area. As this occurs southerly low-level flow will strengthen and push the front northward as a warm front. This will cause some drizzle/light showers to develop overnight tonight with the highest chances in our far northern counties. Scattered to numerous showers will continue across much of the area Wednesday into Wednesday evening. Some weak instability will be present for a small chance of a thunderstorm but HREF thunder probabilities are only 10 percent or less. Generally warmer temperatures are expected, though if coverage of rain ends up being higher than high temperatures could end up lower than forecast. The front drifts back to the southeast as a cold front but quickly stalls. With the stalled front in the area some low rain chances continue into Thursday.

Friday through Monday:

Attention then quickly turns to the winter storm that will impact much of the southern CONUS as we go into the weekend. A cutoff low will drift slowly eastward off the coast of California and the Baja, resulting in persistent moist southwest flow aloft/isentropic lift downstream. Meanwhile at the surface a very strong 1050+ mb Arctic high will build southward across the Central CONUS, with a shallow Arctic airmass moving underneath warm air advection aloft. Rain will overspread the area Friday/Friday night as the Arctic front moves in. Temperatures look to drop below freezing in the far northern counties as early as Friday night or as late as during the day on Saturday morning. This will be the main thing to watch as we get closer, since models often struggle with the timing of shallow Arctic air masses. Forecast soundings indicate a large warm nose aloft that will melt any snowflakes, with a predominant precip type of freezing rain. In the northern counties there will also be the potential for a changeover to sleet as the low-level cold air mass deepens. Temperatures won't warm up much on Saturday and will be falling in many areas during the afternoon.

Temperatures really start to drop on Saturday night though there starts to be quite a bit of spread in temperatures in the guidance by this point. This will result in the potential for wintry precipitation to expand to cover much of the rest of the forecast area. It is interesting to note that some guidance does indicate a dry layer at 700mb pushing in, which is why current ensemble blends show a decrease in PoPs. However, there remains quite a bit of moisture above and below this layer, and even light freezing rain/freezing drizzle at these temperatures could have significant impacts. Additionally, any remaining water on roadways from earlier rain will have the potential to refreeze. The current forecast shows precipitation chances tapering off from northwest to southeast by Sunday though there remains quite a bit of spread in the guidance. Will keep in mind that any time a cutoff low is involved there is always the potential for systems to slow down.

The latest probabilistic WSSI shows medium to high chances (40-70%) of at least minor winter weather impacts for areas along and north of I-10, with at least low (20%) chances extending southward towards the coast. Probabilities for "moderate" winter weather impacts are 20-30% across northern portions of the forecast area. However, it is important to note that WSSI can under-do impacts for freezing rain since small amounts of ice accumulation can have big travel impacts. It's too early for any Winter Storm Watches at this time, but those will probably eventually be needed for at least part of the CWA in the next day or two. Current forecast winds are sustained around 10-12 kts with gust to 20kts, which may also aid in power outages.

While there is a understandably a lot of focus on the wintry precipitation, it is also important to focus on the dangerously cold temperatures also occurring with this system. Hard freeze conditions (temperatures below 24 degrees) are expected across portions of the area Saturday, Sunday, and Monday nights, with the coldest temperatures/most widespread temperatures below 24 degrees Sunday night. Forecast lows in northern portions of the area are in the teens on those nights. Dangerously cold wind chills are also forecast, with the lowest values Sunday morning ranging from the single digits north to the teens south. At minimum widespread Cold Weather Advisories (wind chills below 20 north/25 south) will likely be needed. Additionally, some Extreme Cold Warnings (wind chills below 10 north/15 south) will probably be needed.

Make sure to continue to check back for the latest forecasts with system since it is still a few days away and forecasts will likely change. Now is the time to begin to prepare.

JDavis

AVIATION

(12Z TAF Issuance) Issued at 531 AM CST Tue Jan 20 2026

VFR conditions prevail through today. Light and variable winds will become easterly this morning, and will transition to E/SE this afternoon at around 10 kts, occasionally gusting to 15 kts. Increasing cloud cover this afternoon will lead to BKN to OVC skies. Overnight into Wednesday, expect CIGs to lower to MVFR levels for the majority of SE Texas beginning anywhere between 4Z and 6Z. Expect MVFR CIGs to prevail through the end of the TAF period. Rain will begin to move into the area early Wednesday morning, increasing in coverage Wednesday morning (past the current TAF period)

MARINE

Issued at 136 PM CST Tue Jan 20 2026

Mariners should remain mindful of negative tide levels again today, mainly across the northern bay areas around low tide cycles. A tightening pressure gradient will lead to some increasing Gulf winds today. A Small Craft Caution has been issued for the Gulf waters for winds of 15-20 kts. A weak coastal trough is expected to develop and move eastward bringing periods of showers on Wednesday into Thursday. Patchy fog is also possible Wednesday night and Thursday morning, but conditions do not appear overly favorable for prolonged stretches of the dense variety. An Arctic cold front is expected to push into the coastal waters late Friday or Saturday bringing hazardous marine conditions: a much colder airmass, strong north winds and building seas through the weekend. Periods of precipitation are anticipated through Saturday. Advisories are likely, and Gales cannot be ruled out. Mariners are advised to keep up with the latest forecasts.

PRELIMINARY POINT TEMPS/POPS

College Station (CLL) 55 67 55 73 / 40 60 30 10 Houston (IAH) 57 69 60 74 / 20 70 40 20 Galveston (GLS) 59 68 58 68 / 20 70 50 30

HGX WATCHES/WARNINGS/ADVISORIES

TX...None. GM...Low Water Advisory until 6 PM CST this evening for GMZ335.