Sunday update on this weekend’s heavy rain and the tropical threat

In regard to rainfall and the Houston metro area, we have two separate issues to discuss. There is the potential for heavy rainfall on Sunday, Monday, and Tuesday; and then the renewed potential for heavy rain toward next weekend, as a tropical disturbance—perhaps Tropical Storm Gordon—brings rainfall to the northern Gulf of Mexico coast.

A satellite image from Sunday morning showing both systems. (NOAA/Space City Weather)

Labor Day Weekend

A weak low pressure system over southern Louisiana and the northern Gulf of Mexico will drift westward over the next few days, bringing an excellent chance of rain to the Houston metro area on Sunday, Monday, and Tuesday. The National Weather Service will issue a “Flash Flood Watch,” and there is a general expectation of 1 to 4 inches of rainfall, with isolated areas seeing as much as 8 inches. The best chance for heavy rainfall will come on Sunday night, and throughout Labor Day. If you have travel plans on Monday, please to check conditions before venturing out. For the most part we expect street flooding, but can’t rule out some more serious effects in areas where the storms establish themselves and don’t really move.

Synopsis of Labor Day weekend rain. (National Weather Service)

We have reasonable confidence that after this system clears the area, we should see somewhat drier conditions on Wednesday and Thursday for Houston, with partly sunny skies and more scattered showers. Which is a good thing, because …

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Some kind of tropical system likely in the Gulf next week

Houston continues to face the prospect of a wet Labor Day Weekend—but we’re not concerned about anything more than the potential for some street flooding and spoiled outdoor barbecues with intermittent showers and thunderstorms.

However, we did want to update you on the potential for tropical mischief in the Gulf of Mexico next week. Some forecast models have become a little more bullish on low pressure forming in the northern Gulf next week, which could lead to development of a tropical storm. As of Saturday morning, the National Hurricane Center predicts a 40 percent chance that a tropical depression or storm will form during the next five days.

Tropical Weather Outlook. (National Hurricane Center)

There are a lot of uncertainties with this system, and forecast models are having a difficult time resolving them. Of course, everyone will want to know where this will go. However, that’s simply impossible to say without a reasonably well defined low pressure system, and that probably won’t exist for a couple of days.

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Wet weekend at times, tropics “noise” continues

Thursday saw another mixed bag of weather, with some folks seeing heavy rainfall and others seeing not much of anything. We should replay that program today before better odds of rain and storms return this weekend.

Today

Expect at least a handful of showers and thunderstorms today. Not everyone will get rain, but those that do could see some heavier downpours. In terms of coverage, it will probably be similar to or less than what we saw yesterday, with the best chances the closer you get to the coast. Today probably carries the lowest rain chances of the next several days.

Temperatures will range from the upper-80s where you see showers to the low-90s further inland with drier weather more likely.

Holiday weekend

We’ll see another disturbance about 20,000 feet up migrate toward us this weekend. What does that mean? It means gradually increasing rain and storm chances again. Saturday shouldn’t be a washout, but there will be a few more showers and storms than we saw yesterday and will see today. Sunday may be when the more widespread showers and storms impact us. Some of the rain on Sunday could be locally heavy. Additional widely scattered showers and storms will remain with us for Labor Day.

Rainfall through Sunday evening should average close to a half-inch, with higher amounts likely in spots, especially south and east of Houston. (NWS)

Best course of action this weekend? Have a rain plan ready to implement if you’ve got any outdoor activities. In some cases, you won’t need to use it, but given the erratic nature of rainfall in these setups, it would be good to have a plan to turn to. We don’t expect any serious flooding this weekend, but as is almost always the case in Southeast Texas storm setups, locally heavy rainfall could lead to brief, localized street flooding in areas of poor drainage.

Also worth noting, the tropical thunderstorms this weekend could be capable of producing funnel clouds or brief waterspouts, especially in the morning near the coast. Just something to keep in mind if you’ll be at the beach this weekend.

Expect temperatures in the upper-80s most days, with low 90s inland if rainfall doesn’t materialize quite as much as anticipated.

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Lots of moisture in store for Texas, but no specific threats

Some parts of the greater Houston region received heavy showers on Wednesday, with several readers reporting upwards of 3 inches of rainfall in an hour. Other areas within the metro area saw no rain at all, just distant lightning. Rain coverage should back off a little bit today and Friday before more widespread showers likely return this weekend. As moisture moves into the Gulf, this pattern should continue.

Rainfall accumulations on Wednesday in Houston. (Harris County Flood Warning Service)

Thursday and Friday

Some slightly drier air has moved into the atmosphere, and this may help dampen—oops, wrong word there, I should probably say reduce—shower chances for the next two days. That is not to say it won’t rain, but rather that instead of 50 to 60 percent rain chances, it probably will be more like 30 to 40 percent, with the lower likelihoods inland, and slightly better chances near the coast. Highs will depend on local conditions, but will probably range from 90 to 95 degrees.

Saturday

By Saturday, the pattern will begin to shift toward wetter weather again, a the upper air pattern again favors the movement of more moisture into the Texas coast. Saturday doesn’t appear to be too waterlogged at this point, and it should be at least partly sunny. However, especially during the afternoon hours, there probably will be a healthy amount of showers and thunderstorms popping up across the Houston area. Highs in the low 90s.

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