Forecast comes into better focus as tropical system will soon emerge into Gulf

Space City Weather
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Originally published at: Forecast comes into better focus as tropical system will soon emerge into Gulf – Space City Weather

In brief: We expect widespread showers and thunderstorms today, particularly south of I-10, where flash flooding is possible. Our current thinking is that a tropical disturbance expected to track across the Western Gulf on Wednesday will remain far enough offshore to spare Houston from significant flooding, but we’re going to watch things closely.

Behold, the tropics

As of this morning a low pressure system located over South Texas is starting to move toward the Gulf. On Wednesday it should move to the northeast, just off the Texas coast, toward Louisiana. At this time it may have a brief period during which it can spin up into a tropical depression, or possibly a named storm (it would be called Arthur). The National Hurricane predicts there is a 60 percent chance this occurs. Although certainly there would be a lot of noise around a tropical storm forming in the Gulf so close to Texas, we’re here to tell you the impacts from this system are going to be similar regardless of its development in the coming days.

And there’s some good news in the forecast. Remember how we’ve been talking about the boom or bust potential later this week, on Wednesday and Thursday, due to heavy rains from this tropical system? As of Tuesday morning we are leaning toward bust. Put another way, after today and this evening, our rain chances will probably trend down somewhat. And we think the likelihood of very heavy rainfall (i.e. bullseyes of 10 inches or above on Wednesday and Thursday) in the Houston metro area is low. It’s not zero yet, but things are trending in the right direction. There will be some winds and tides to contend with, but nothing too significant. More on that below.

Tuesday

In terms of heavy rainfall, conditions will be most favorable today across the Houston region with rich tropical moisture spreading into the area. There is a thick band of heavy rainfall offshore the Texas coast this morning, spreading all the way from Corpus Christi to Port Arthur. The key word there is offshore. Some of this activity is spreading inland this morning, and we expect rains to move into the Houston area today. Due to the tropical nature of this airmass, rainfall rates could be quite high, quickly leading to street flooding (and hence, our Stage 2 flood alert).

Rain accumulations today should be highest along and to the south of Interstate 10. In these locations 2 to 4 inches of rain will be possible, with some isolated areas of 6 inches possible. Further north totals should be less. Due to the rain-cooled air mass temperatures today for most locations should be in the 80s, with lower 80s likely near the coast. Rain chances should slacken somewhat overnight, but there will still be pockets of activity.

Wednesday

The aforementioned tropical system should pass closest to Houston on Wednesday. At this time we think it will track southeast of our region, remaining off the coast. In this case it should keep the heaviest rains offshore. The major risk at this time is if the system tracks more to the north, and moves inland into the Upper Texas coast. This would mean more rain over the Houston metro area. To be clear, we don’t think this will happen, but we are watching for this possibility and will of course keep you informed.

Anyway, our best-guess forecast at this time for Wednesday is for about a 60 percent chance of rain showers, with better chances and higher accumulations closer to the coast. For now rain totals look fairly manageable, with 1 to 2 inches, but again this would change if the tropical system took a more northerly route.

We are also likely to see some coastal wind gusts of about 30 mph, starting early Wednesday morning. I’m not sure how far inland these will extend, but it’s possible they could reach areas such as Pearland or League City. (Again this is dependent on the tropical system’s track). Water levels will also be 1 to 3 feet above normal tide levels, so there could be some minor coastal flooding. High temperatures on Wednesday should be in the upper 80s.

Thursday and Friday

At this time we expect rain chances to step back on Thursday and Friday, likely back into the 40 percent range. These likely would be more of your typical summertime showers and thunderstorms rather than anything too serious in terms of flooding potential. Highs will likely reach the lower 90s with more sunshine.

Saturday, Sunday, and beyond

The weekend looks to be partly to mostly sunny, with high temperatures in the lower 90s. There probably is about a 40 percent chance of rain on Saturday (hard to have too much confidence one way or other here), with lower chances on Sunday. Most of next week will probably see highs in the lower 90s, with the potential for scattered showers but fairly low chances overall. Basically it should be a return to normal programming for June in Houston.

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arthur
arthur900×506 113 KB

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This isnt directed to space city weather, but its incredibly frustrating that in 2026, the accuracy of forecasting storms is incredibly low.

I have a staff i have to take into account as to whether they should come into the office or not, and more often then not, doomsday forecasts of torrential rains never happen. I have staff at home and i feel completely foolish for listening to the forecast.

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Welcome to our quiet tropical El Nino year…

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Thanks for the update, good job with these tricky forecasts. I like how you repeated that it could be a yes or no, boom or bust. Never attach a 100% to any forecast, no one has complete control on weather. :victory_hand:t3:

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Those Flooding rains north of I-10 going gangbusters.

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Honestly, I don’t expect that will ever change. As long as I’ve been alive, I can remember rainfall forcasts either being overblown or underblown. Forcasting what the weather is going to do to with percision accuracy is a very difficult thing to do even for the best technology.

Short of a magic ball, it is nearly impossible to perfectly predict the intricate workings of an atmosphere that can change on a dime with the slightest bit of a whim. However, sometimes weather forcasts can be near spot on. For example, Harvey and Alison are 2 events I remember them being pretty accurate on. So every once in a while weather forecasting can hit the bullseye. But in large part, weather focasting is good enough to give you a general idea of what to expect in the short term with average run of the mill weather. It just seems to have trouble with the extreme events.

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As a lifelong resident of the gulf coast, I reached a point many years back that I simply refuse to alter any plans I did or didn’t have based on a weather forecast. They are simply not accurate enough. When I got my private pilots license, I learned that aviation weather forecasts don’t go out further than 24-36 hours. I questioned my instructor why, and was told the validity of anything beyond that window is too low to base your life on while piloting a plane. Well said, sir.

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Yep. Weather is a classic example of a chaotic system, where extremely minor variations in starting conditions can have wildly compounding effect on ending conditions. Predicting it, at least with the tools currently available, is a matter of running sophisticated computer models over and over again with small variations and seeing if all the different runs roughly cohere, then deciding on a way to average them out and wring a forecast out of it. We’re limited both by the computing power available and also the accuracy of the models, which even at their best can only approximate the behavior of physical systems made up of trillions of interacting molecules all doing their own things.

And even with all the computing power in the universe available, perfect forecasting would still be impossible because you can never sample the full exact state of the atmosphere and all its components to give you a “true” starting point. And, if the initial state can never be molecule-exact, you’ll always have deviations between the prediction result and the end result.

Without some way to get around thermodynamics and the “butterfly effect”—and nothing like that is in the cards!—weather prediction more than a couple of days out will always be uncertain. It’s just kinda how it is, thanks to fundamental properties.

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That was beautifully stated! :clap: :+1:

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Keep in mind the current admin’s attacks on science and funding to exactly the tools we use to forecast weather.

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