Tropics update: Heaviest rains may remain east of Houston

Here’s an afternoon update based upon the latest model guidance for the tropical system, Invest 93L, now located in the southern Gulf of Mexico. A hurricane hunter is investigating the system this afternoon, and it may be upgraded into a depression or storm later today.

It’s best not to think of this system as a classical tropical storm or hurricane, but rather, as my colleague Matt Lanza puts it, “an atmospheric river” of moisture flowing from the south into the United States. In other words, we’re dealing with something that’s going to bring a lot of rain to someone along the Gulf of Mexico coast. Consider the following forecast, from the European model, for precipitable water values on Wednesday night.

Precipitable water values for Wednesday night. (Ryan Maue/Twitter)

Any value above 2 inches of precipitable watyer is quite high, and you can see that although the center of this storm is near the Texas coast, it is funneling a massive amount of moisture from the Gulf of Mexico into Louisiana. That spells a heavy rainfall event.

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Tropical system moving into Gulf, likely aiming toward Texas or Louisiana

The heat is on for Houston. Sunday’s official high temperature reached 96 degrees, and we’re going to have a couple of more days in the mid-90s, with isolated to scattered showers and thunderstorms, before our weather may change significantly by Wednesday due to a tropical system. Or not. Here’s the latest on what we know about Invest 93L, the system moving toward the southern Gulf of Mexico.

Organization

The storm remains very large and disorganized, producing fairly heavy rains on its eastern side. The best estimate as of Monday morning is that its center is now moving across the northern tip of the Yucatan Peninsula, and will emerge into the southern Gulf of Mexico later today.

“X” denotes approximate center of circulation. (NOAA)

A hurricane hunter is scheduled to investigate the system this afternoon to better characterize its organization, and the National Hurricane Center still rates it as a 90 percent chance of becoming a tropical depression or storm this week.. But as we’ve been suggesting, it’s unlikely to find overly favorable conditions to strengthen in the Gulf of Mexico, so the primary threat from the system will be heavy rains.

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Tropical system nearing southern Gulf definitely worth watching

We’re continuing to watch the development of a tropical disturbance in the Caribbean Sea, near the Yucatan Peninsula, that is moving toward the Gulf of Mexico. This system could play a major role in the Houston region’s weather later this week—or very little. But it’s something I think is definitely worth paying attention to.

Will it develop?

At present the system is a broad area of low pressure, but a lot of forecast models are bullish on its development into something akin to a relatively weak tropical storm over the next few days. The National Hurricane Center believes this, too, giving it a 90 percent chance of development into a tropical depression or storm during the next five days. (A hurricane hunter may investigate the storm later today). Although we can’t rule it out, this tropical system appears unlikely to reach hurricane strength, and therefore the primary threat will be a lot of rainfall.

Satellite image of the tropical system on Sunday morning. (NOAA/Space City Weather)

Where is it going?

This is the key question, and one that remains difficult to answer. We can be reasonably confident the tropical system will slowly move across the Yucatan Peninsula today and Monday, and thne find itself in the southern Gulf of Mexico. But this is the easy part of the forecast.

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Hot, quiet weekend ahead, but forecast headaches loom

Hot, hot, hot! Thursday was the hottest day of the year so far in Houston. We hit 95°, which is right about average for our first 95° day of the year. Typically, our first 95° day occurs about June 13th (based on records back to the 1880s). Fun fact: In 1899, we didn’t hit 95° for the first time until August 8th! If only…

Today & Weekend

With our first 95° in the books, we’ll try and tack on at least one more this weekend. High pressure should dominate the next two to three days, keeping us mostly dry and hot. I suppose we can’t entirely rule out a stray downpour Friday, Saturday, or Sunday, but for the most part, the only detriment this weekend will be the heat. If you’re outside, make sure you stay hydrated, wear sunscreen and find some shade when possible. It’s very basic, common sense stuff, but it’s always worth a reminder.

NWS forecast highs are once again close to the middle 90s today. (Weather Bell)

 

All three days should see low to mid-90s for highs. Nighttimes will be sultry, with upper 70s in Houston and about 80 degrees along the Southeast Texas coast. Galveston will offer limited relief at night this weekend.

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