Matt Lanza

In brief: We are pushing out a Stage 1 flood alert for today based on developments since this morning. Locally heavy downpours will almost certainly cause some street flooding around the area, primarily of the nuisance variety, so use caution the rest of the day if out and about.

Update: The flash flooding threat has mostly ended. We will go back to normal, ending the flood scale alert and referring you to our Friday AM post for the weekend outlook.

We’re going to update things today, as it appears we’ve got some sluggish movers out there. We’ve already seen a couple flood advisories this morning, and some chunks of the area have received 1 to 4 inches since Tuesday.

As such, we’re going to fire up the flood scale for Stage 1 today. I would bank on at least a few areas seeing flooded streets today that may inconvenience travel as the afternoon wears on. So, use caution out there today, particularly in areas of persistent downpours. Off and on rain and thunder is likely to persist and maneuver around the area through early evening before hugging the coast at times again overnight, possibly spreading inland a bit again as well.

So use caution out and about, and we’ll let you know if things should escalate further, though we don’t believe that to be so today. Our next update will be planned for Saturday morning unless the situation warrants otherwise.

In brief: Another round or two of showers and storms will pelt many parts of the Houston area today, with some locally heavy rain possible. Rain chances will start to slow this weekend into early next week before the next round of rain chances kicks off around midweek. There are no current tropical concerns for the Houston area.

Yesterday’s storms were relatively squirrely, especially down in Brazoria and southern Fort Bend Counties. There was a 66 mph wind gust reported from a CenterPoint weather sensor at Brazos Bend State Park. Fascinatingly enough, the radar looked rather innocuous with the storm at the time, but some strong wind gusts elsewhere, including nearly 50 mph just west of Damon seem to back that reading up. That’s just the thing with storms this time of year in Houston: If you catch one at the wrong point in its life cycle in the wrong way, it can produce some pretty quick, short-lived but nasty impacts.

Today

Already today we’ve seen plenty of thunder and some wind gusts up near 50 mph near San Luis Pass. As of this writing, the heavier storms are all offshore, with some isolated downpours and lightning outside the Beltway in western Harris County back through Sealy and Columbus.

As the day goes on, we may actually see things calm down a bit for a time before ramping back up again this afternoon or this evening. I’m not entirely confident on the timing of the next wave; some modeling is quick and quite aggressive with coverage of the next wave of showers as early as late morning. Others hang development back until late afternoon. But we do know a second wave of scattered downpours is likely later today. Expect a very sporadic pattern of coverage with some places seeing squat and others seeing as much as 2 to 3 inches in short order.

Weekend

A continued chance of showers and thunderstorms will be with us on both Saturday and Sunday, as is typical for August. We do think coverage and some of the intensity of the storms will wane a bit on both weekend days, with perhaps Sunday having even less coverage than Saturday. We may see another rude early wake up in spots on Saturday morning as some nocturnal storms could pop up after midnight between Houston and the coast. Then I think we’ll see a summer pattern of mid to late afternoon isolated to scattered downpours resume.

Look for highs in the mid-90s, with a few isolated upper-90s possible.

Monday and Tuesday

We think things will be similarly subdued like Sunday to start next week. Rain chances certainly are not zero, but they’ll remain lower. Highs should again be in the mid-90s.

Midweek next week

We should see another boundary drop in or develop over the region around midweek next week. This should mean an increase in shower and thunderstorm coverage once again. Look for cooler daytime highs as a result.

Total rainfall between today and next week is likely going to be around 1 to 3 inches near the coast, with lesser amounts inland. Isolated higher amounts are possible anywhere in the area, and yes, some isolated places will see lower amounts too.

Tropics

The map currently favors us for the most part.

Of the activity out there today that we’re monitoring, only Invest 99L is worth keeping an eye on. No reliable model guidance is bringing it to the Gulf, but just out of respect for the calendar and history, it’s important to just check in and see if southern tracking waves like this one heading for the Caribbean can survive enough to get closer. Even if it were to do that, I’m not sure that the upper pattern would allow it to come north much, if at all. So either way, this probably ends up buried in Central America ultimately. But we’ll babysit it anyway. Other than that, you can continue to assume the brace position as we navigate the final 5 to 6 weeks of our peak hurricane season. We’re all just trying to get to the finish line.

In brief: Invest 98L, the Gulf tropical disturbance, will bring an enhanced chance of showers or storms to Houston today and Saturday, but nothing much more than that. After that exits, we maintain typical August weather with heat, humidity, and daily shower and storm chances.

Today/Invest 98L

First off, let’s get the elephant in the room taken care of: Invest 98L, the tropical disturbance approaching the South Texas coast is becoming less likely to develop now, particularly because it’s quickly running out of runway to work with. Odds remain 50% per the NHC, though if it does develop, it would be a tropical depression for about 3 to 6 hours or less before reaching land in South Texas.

That being said, it looks somewhat interesting on satellite this morning, conversationally at least.

This may look a little scary, but in reality, there is no low-level circulation so while there are some heavy thunderstorms and heavy rain underneath this blob of clouds, the system is not organizing much. So you can disregard any meaningful tropical development (wind, coastal flooding) elements of this for the most part.

What we will watch for at least is rain.

We don’t expect a ton of storms here today. But as this blob of storms lifts toward the coast, watch for development coinciding with daytime heating from Matagorda Bay up through Galveston, quickly moving inland. The one thing that will probably limit flooding is that storm motion today looks pretty quick. Unless we end up seeing several storms in a row over the same area, expect a few places to see perhaps an inch or two in less than an hour, some quick, minor street flooding, and then hopefully calmer weather. It’s possible that we also see a localized stronger storm with gusty winds as well.

Overall, the impacts of the tropical disturbance should be for a slightly more active August afternoon today. Even on slightly active days, some neighborhoods may not see any rain at all, so that’s possible too.

It’s extremely humid outside this morning as some of that added moisture works into the area. We had some of our warmest overnight lows of summer in some parts of the region yesterday, and we’ll be close to matching or exceeding them today (Jamaica Beach has not fallen below 86 degrees as of this writing for example).

Saturday

With the tropical disturbance dissolving inland, we’ll be left with added moisture and onshore flow Saturday. For now, I’d say this is pretty typical August weather, but I wouldn’t be entirely shocked to see a few repetitive thunderstorms that cause some minor street flooding tomorrow. Otherwise, just look for high humidity and warm to hot temperatures in the 90s.

Sunday & Monday

We should see relatively calm weather here, with just a continued slight chance of afternoon thunderstorms. Coverage should be a little less than it will be today and Saturday however. Highs in the mid-90s.

Rest of next week

High pressure is going to flex and expand in the Rockies and central Plains. This should open the door to some rain and thunderstorm chances out of Louisiana into southeast Texas, combining with sea breezes in the area to keep us somewhat active. Look for mid-90s continuing.

In brief: Hot and humid weather with daily shower chances awaits Houston over the next several days, typical for August but perhaps encroaching on 100 degrees at times. Today, we also dive in deep on the tropical noise that’s been percolating on some weather models.

IAH hit 100 degrees again yesterday. Before you go stand outside Terminal B with pitchforks due to construction the perceived hot bias, there were a string of 99s and 100s yesterday recorded across the north and west side of town. Wednesday’s 100 felt a little less valid. But again, compare IAH to IAH, not to the rest of the city. We saw mid to upper 90s mostly, and we’ll probably do it again today. Nothing unusual for August.

Today

We’ll have one more slightly hotter than usual day today with highs approaching 100 degrees in spots, especially north of I-10. Isolated to scattered showers and thunderstorms are likely with daytime heating again, and any of those storms could produce some brief downpours and the potential for some gusty winds.

We may still have residual haze, especially this morning. That’s due to wildfire smoke from Canadian wildfires. This is a problem that much of the country has been dealing with at times in recent years.

Weekend

Both days should be fairly typical for August. We’ll see highs in the mid to upper-90s, possibly leaning more toward mid-90s on Sunday with slightly higher coverage of showers and storms. But, sunny, hot, and humid with daily isolated to scattered downpours and thunderstorms.

Next week

There’s nothing particularly notable about next week’s weather right now. It looks like we’ll have a few isolated to scattered showers or storms each day, especially on Monday or Tuesday. Temperatures may try to rebound back closer to the upper-90s again. But overall, it looks like very basic August.

Tropics

First and foremost, we’re good here for the next 7 to 10 days in Houston. We’ve got no concerns noted on modeling right now.

All that said, it’s getting to be the time of year where we do start watching more and more things, even some of the innocuous looking ones. We’ve had some deterministic (operational) model guidance (the GFS, the Euro, etc.) go crazy in the day 14 to 16 timeframe lately. This bears repeating. The day 14 to 16 timeframe. Deterministic modeling has virtually no skill at that timeframe. So, while we are certainly empathetic to people getting a little unnerved when they see bad things in that timeframe, Eric and I both are realists and recognize that those runs, even if 2 or 3 in a row show something similar, are somewhat meaningless. Put another way, if I had a buck for every time a deterministic model wrecked a major Gulf Coast city on days 14 to 16, I’d be getting wrecked on some tropical island somewhere far, far away living the dream. I’m just saying!

So what do we do instead? We look at ensemble guidance for clues. What can the ensembles tell us about the potential for a tropical system in a more distant timeframe? Ensemble modeling is where you take a single model and run it 30 to 50 times but tweak the initial conditions, or what the model starts from. We can’t get a perfect snapshot of the entire atmosphere over the entire globe, so we have to improvise a little. Ensemble guidance is that improv.

Okay, let me show you a perfect example of this. Here’s last night’s GFS operational model for hour 294, which is day 13.

That’ll get your attention! And it has been showing this for a few days, though it varies in location between the Caribbean, the Carolinas, and out to sea. But what do the ensembles show?

Not all lines on a spaghetti plot chart are created equal. Some of the lines above may be ensemble members that are slightly more skilled than others. That’s a tough lift to figure out specifically in every situation. But the point is this: Yes, the GFS operational model may be right! But according to the ensembles there are a bunch of other options too, including many that go out to sea and a handful that come into the Gulf.

I show you this for a couple reasons. First, I want you to recognize that the scary images you often see on social media are almost always from operational models. Second, when you look at the ensemble guidance, it offers a far more nuanced take on all this that suggests the operational models are just one possible solution of many. We go through this exercise every season. It’s the same culprits from the same places with the same intentions. They’re basically preying on people’s fears to drive engagement under the guise of “we’re not saying this is a forecast (it is), but we want to just let you know what’s out there!” In reality, the picture is nuanced, complex, and not at all straightforward. A deterministic model showing Armageddon on day 13 does not make that scenario any more likely than any of the possible outcomes on the ensemble chart I showed you above. Hurricane season is a months’ long marathon. We just want you to keep your sanity.

In this specific situation: Yes, we should keep an eye on this tropical wave as it comes west over the next 10 to 12 days. It is August, and we should keep an eye on all tropical waves this time of year. Rest assured, if there’s a threat that seems realistic to Texas, we’ll be talking about it here well before it happens. You can also use The Eyewall to follow along with more of the day-to-day details.