Confidence growing in Texas impacts from Invest 97L

Good morning. This post will consist of both a short weather update about the rest of this week, and a longer section on the threat posed by the tropics. In short, the latest model guidance suggests an increased likelihood that Invest 97L may impact Texas, although much uncertainty remains. We’ll also have to keep an eye on Invest 98L, although this seems a bit more of a distant threat.

Thursday

Today’s weather will be a lot like Wednesday’s, which is to say hot and sunny, with high temperatures in the mid- to upper-90s. With slightly drier air in the region, conditions won’t feel quite so humid this morning or this evening, but as an easterly, and southeasterly wind develops this afternoon we’ll feel the beginnings of an onshore flow. A few stray showers may develop near the coast today. Low temperatures will fall into the mid- to upper-70s.

Friday, Saturday, and Sunday

Honestly, we don’t anticipate a whole lot changes with our weather and this August-like pattern, except that the onshore flow will return more humidity at the surface. We’re going to see hot days in the mid-to-upper 90s with oodles of sunshine and only very slight rain chances with coastal counties the most likely areas to see precipitation.

Next week

Our weather next week will depend to a large extent on Invest 97L, but the bottom line is that we may see increasing rain chances by Monday or Monday night. This is probably a good time now to talk tropics.

Invest 97L

This system has become slightly better organized overnight, and forecasters now give 97L high odds of becoming a tropical depression or storm within the next 48 hours as it moves toward the Yucatan Peninsula. Before we talk about the track forecast, it’s important to remember that before a well defined center of circulation forms, overall confidence is low. With that said, probably the most significant change today is that the potential for 97L to take a right-ward turn toward the northern Gulf of Mexico coast is lessening.

To understand why, here’s a forecast for overall steering currents by this weekend. A high pressure system over the Atlantic will be expanding westward. Meanwhile, a trough of low pressure begins to pull away, to the north. If this trough hangs on long enough, it will pull 97L toward the uppper Texas coast, or Louisiana. If the high pressure system builds faster to the west, it will push 97L into south Texas or Mexico.

Because of these competing features, and lack of a well defined center, we just don’t have great confidence in track forecasts. However, the global ensembles do seem more confident in a track toward Mexico or Texas next week. Here’s the European model forecast for the position of 97L by Tuesday evening. We’ll talk more about Tropical Depression 13 below, so ignore that for now.

So if Invest 97L may be coming toward Texas or Mexico, how strong will it get? None of the models seem particularly bullish on anything more than a tropical storm, and that is probably because wind shear may be fairly high in the western Gulf of Mexico early next week. Let’s hope for shear, because otherwise the Gulf of Mexico is plenty warm to support strengthening into a strong tropical storm or even a hurricane.

In any case, moisture should begin to arrive in Texas by Monday, leading to elevated rain chances. Beyond this it’s difficult to say much about impacts from 97L given the uncertainty surrounding its track and intensity.

Tropical Depression 13

The system behind Invest 97L became a depression on Wednesday night, and should become a tropical storm within the next day or so. (The next named storm, whether this one or 97L, will be named Laura). This depression is expected to track west-northwest toward Florida this weekend.

While it probably will be a problem for that state and possibly the eastern Gulf of Mexico, we cannot entirely rule out a more westward track that brings a storm to Texas late next week. But for now it’s probably best to focus on 97L as that has a higher likelihood of affecting Texas.