Tropics sizzling, but Houston threats seem manageable. Probably.

A solid round of showers and thunderstorms rolled through Houston on Monday during the daytime, dropping 0.5 to 2.0 inches of rain for most of the area. It now seems likely that the radar will quiet down for most of this evening, before heavier showers being to develop along the coast on Tuesday morning like on Monday morning. The National Weather Service has prudently kept a Flash Flood Watch in place for coastal counties, and the inland tier including Harris County, through noon Tuesday (Note: after this post was published Monday afternoon, the flood watch was extended until 6pm CT Tuesday. Our forecast remains unchanged.) The best hope is that the heaviest precipitation stays just offshore, rather than migrating on shore during the next 24 hours or so.

Area of flash flood watch. (National Weather Service)

Unfortunately, rain chances are not going to go away on Wednesday and Thursday. Although rain showers should be more scattered in nature, and perhaps less intense, we definitely can’t rule out locally heavy rainfall due to the tropical air mass and overall stagnant pattern. Given all of this, we expect accumulations of 1 to 3 inches for inland areas from now through Thursday, with 2 to 5 inches more likely for areas immediately along the coast (with higher isolated totals). The primary threat should be street flooding rather than significant stream and bayou flooding.

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Between rain and the tropics, Houston’s weather will be pretty lousy

Man, I hate this time of year. Invariably, the tropics reach their crescendo, and this year is no different. In fact, this is only the 11th time on record that three hurricanes have been active in the Atlantic simultaneously, Florence, Helene, and Isaac. This week, Hurricane Florence will rightly suck up a lot of the national oxygen—Matt did a commendable job of summarizing the risks to the Carolinas and beyond, and they are tremendous in terms of flooding, wind, and surge—but we have some homegrown threats to consider as well.

Tropics as of 7am CT on Monday. (National Hurricane Center)

For this post we are going to focus on the near-term threat of heavy rainfall on Monday and Tuesday, and then the late-week threat from a nascent tropical system. Did I mention that I hate this time of year?

Monday and Tuesday flood watch

The National Weather Service has issued a Flash Flood Watch for the coastal and inland tier of counties for 1pm Monday through Tuesday morning, and they admit they may have to extend it. Basically, we have a lot of low pressure hanging around and a super-moist atmosphere. I think at best we can hope for scattered, heavy rain showers; and at worst we probably will see some spots of 3 to 6 inches over the next two days. Most likely the hardest hit areas will be along the coast, and if we’re lucky the heaviest rains will fall offshore.

Area of flash flood warning in effect through Tuesday morning. (National Weather Service)

Both Monday, Monday night, and Tuesday will probably be similar in this regard. We’ll just have to watch radar trends and if you have to drive for more than a short errand, you should probably check road conditions at your destination. This shouldn’t be anything more than street flooding, but we can’t guarantee that.

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Locally heavy rain for Houston early this week; watching late week tropical wave

Sorry for a later update than I would have hoped. Cable/internet outage due to storms and daddy duty called!

Lots of rain in and around the Houston area today, so we want to provide you a quick refresh on what’s going on with this rain, the tropics, and what to expect to start your week.

Monday & Tuesday rain

Radar as of this evening shows rain winding down across the area. Total rainfall over the last two days has been variable, with some places seeing minimal amounts and others seeing 2-3″ or even a little more.

Total rainfall since Saturday has been on the order of a half inch or less to three inches or more depending on your location. As usual, Houston rains are quite variable. (Harris County Flood Warning System)

Expect a mostly quiet night tonight. But, as we go into tomorrow, a number of things may come together to produce another round of heavy rainfall in the area. Eric will have more on the timing and the where tomorrow morning, but I would have the umbrella by the door tonight at the ready before you head out for work or school.

Look for more showers and thunderstorms in the area Monday night or Tuesday. It’s tough at this timescale to narrow down specifics, but suffice to say, locally heavy rainfall will be possible. A Flood Watch isn’t posted for the area, but depending on how we do tomorrow, we may need one Tuesday. Street flooding is the main concern with this event.

Total rainfall from tonight through Tuesday evening is expected to average about 1-3″ across the area. Some may see more, others less, however. (NWS)

How much rain? On average, we expect most folks will see another 1-3″ on top of what’s fallen. Since “average” is just a combination of extremes, that means some folks may see less than an inch and others may see four or five inches of rainfall. Again, we don’t expect widespread problems and street flooding is the biggest concern right now.

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Soggy at times this weekend; watching tropics

As Eric has been conveying, this weekend is not going to be the most optimal for the Houston area. We’ve got rain chances in abundance. Thankfully, we don’t anticipate any serious problems from the rain, but if you have outdoor plans this weekend, you may need some alternative options. Let’s walk through it.

Today

Yesterday saw a good bit of rain mostly south of the metro area, down toward Wharton and Angleton and west toward Brookshire, with a few storms here and there elsewhere.So far, quiet this morning, with just a few showers down in Matagorda County. As the day goes on, I would expect scattered showers and storms to fire up with daytime heating, beginning at the coast and spreading inland. Not everyone will see rain, but those that do could pick up a quick half-inch to inch of rain in a cooling downpour.

Expect highs near 90°, but a little cooler if it happens to rain a bit more at your location.

Weekend & Monday

So, let’s start with this: I don’t think this weekend will be a complete washout. If you have outdoor plans, I might not completely abandon them. But I would absolutely have an alternative in place. I think Saturday may be a better day than Sunday, unless you live northwest of Houston. It won’t rain all the time and everywhere this weekend, but where it does rain, it may be heavy at times with some patchy street flooding possible.

Who are we expecting to see the most rain on which day? There will be a weak cold front draped inland over Texas. No, it won’t usher in cool, dry air, but it will act as a focal point for the rains. On Saturday it may be well north and west of the city, out toward Columbus and north to College Station and over into Walker or Madison Counties. By Sunday, it creeps closer to Houston.

The NWS rainfall forecast through Sunday evening is just shy of 1″ on average in most of the Houston area, but there’s a better chance at over an inch both along the immediate coast and northwest of the city. (Weather Bell)

I still think the focus of showers on Sunday may be to the northwest of Houston, but perhaps out toward Katy and up to The Woodlands and toward Livingston, so a bit closer. So it’s conceivable that both days, the majority of the rainfall stays northwest of the Houston area. We’ll still see some scattered showers and storms regardless though.

On Monday that front may creep through the area while falling apart. So, again, scattered to numerous showers and storms with daytime heating, now across the Houston area. Look for temperatures to top off in the upper-80s most days on average (90+ if you don’t see rain, cooler if you see a good deal of it), with lows in the mid-70s.

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