A hurricane may move into the Gulf this weekend

This morning we touched upon the likelihood of a tropical system coming into the Gulf of Mexico this weekend, and now that the National Hurricane Center has declared this a tropical depression there has been heightened focus on the system. As the depression is currently under low wind shear and over warm water (nearly 85 degrees), we can expect this to become Tropical Storm Nate soon. Before we discuss the track and intensity forecast for this storm, I want to be clear that at this time we really do not view this system as a significant threat to Texas.

Likely track of the tropical system between Wednesday afternoon and Saturday. (NOAA/Space City Weather)

Track

The system will interact with Nicaragua over the next 24 hours as it moves north, and perhaps Honduras and Belize, bringing significant rains to those locations. There is general agreement that it will get pulled into the Gulf of Mexico by Friday night or Saturday morning, perhaps passing over northeastern tip of the Yucatan Peninsula, or moving through the straits between the Yucatan and Cuba.

After that time there’s some uncertainty. The GFS model (12z run) wants to keep the system on a north-northwest track, and bring it into Louisiana (or possibly even eastern Texas). Here’s a map showing the ensemble forecast for the “center” of the tropical system on Sunday morning:

12z GFS model forecast for the tropical system. (Weather Bell)

You might look at this and be somewhat alarmed, given the proximity to Texas. However the GFS doesn’t seem to be handling the overall pattern very well, and you would think that if this storm followed such a track it would become quite a bit stronger than what is shown here. Therefore, I would discount the GFS model at this time.

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On the Gulf tropical system, and a cold front next week

After a stormy Tuesday, the rains should be over for now, as high pressure builds over Houston and somewhat drier air works its way into the region. For us, the next two big events to watch for are a tropical system in the Gulf of Mexico, and a much-anticipated cold front next week. Let’s discuss.

Wednesday through Friday

Building high pressure should lead to mostly sunny skies—look for highs in the upper 80s—along with warm nights with lows around 70 degrees. Aside from the late-summer like feel to the weather, we should have no concerns.

Saturday and Sunday

For now, the weekend simply looks pretty hot, with partly to mostly sunny skies and highs near 90 degrees. Lows should only fall to around 70 degrees. The good news is that after this weekend I’d say there’s only about a 50 percent chance of seeing another 90-degree day this year, so the end of summer really is nigh.

Saturday’s high temperatures could be one of the year’s last 90-degree days. (National Weather Service)

The caveat to this weekend’s forecast is the tropical system likely to form in the Gulf of Mexico, which could bring us some increased moisture and rain chances by Sunday—although for now I’d bet against that.

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Chance of heavy rain today, then drier for the second half of the week

As of about sunrise, Houston’s radar is fairly quiet, with just a few showers streaming in from the Gulf of Mexico. However, we expect that to change later this morning, with the potential for widespread showers, and some locally heavy rainfall. After this, we can expect drier weather through the weekend.

Tuesday

There are a few indicators of the easterly flow that’s been piling moisture into Houston during the last few days. The first one is that, if you’ve been anywhere near the coast or bays, you’ve seen water levels a couple of feet above normal. This is just the easterly winds piling water on top of high tide. The second factor is the increased humidity levels of the Gulf of flow. This increased moisture from the Gulf is likely to culminate later today in showers and thunderstorms. We are not too concerned about flooding, but much of the Houston area may well see about 1 inch of rain, give or take. Some isolated areas will almost certainly see more. If there are any concerns later today, rain wise, we’ll be on top of them for you.

Precipitation forecast for Tuesday. (NOAA WPC)

Wednesday

A transition day, as showers end Tuesday night or Wednesday morning. Skies should clear out in the morning or early afternoon, with highs in the mid- to upper-80s.

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Scattered, heavy rain showers possible on Monday and Tuesday

Houston had an all-too-brief taste of drier air this weekend, but already humidity levels are rising, and we’re going to see a fairly warm week for early October. Some (perhaps significantly) cooler weather should finally arrive next week.

Monday

As moisture levels rise, we’ll see a chance for scattered showers—with some isolated, heavy rains possible later today, this evening, and during the overnight hours. Most of Houston may just see clouds, but after a sunny, dry weekend the difference in moisture levels will nonetheless be noticeable. Clouds should limit highs to the upper 80s.

Tuesday and Wednesday

Moisture levels will spike on Tuesday, as an easterly flow brings in tropical moisture. Precipitable water levels will rise above 2.0 inches, and this should allow for fairly widespread showers and some thunderstorms. Some of these storms could be pretty heavy, bringing some localized heavy rains. For the most part, I expect people to see 0.5 to 1.5 inch of rainfall, but some areas will see more than this. We are not too concerned about flooding at this time, but will be watching this closely.

Precipitable water values surge to about 200 percent of normal levels for east Texas on Tuesday. (Weather Bell)

Rain chances will continue from Tuesday night into Wednesday morning, but then should begin to ebb as moisture levels fall, and high pressure builds. Both days should see highs in the mid- to upper-80s.

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