Eric Berger

In brief: Our confidence is increasing in the likelihood of heavy rain across the Houston metro area on Thursday morning, perhaps around sunrise or a few hours later. Flash flooding is possible in the strongest storms.

The overall forecast from the post we published this morning remains more or less on track. However, our confidence is now very high in impactful storms pushing into, and through, the entire Houston region on Thursday morning. Although we still have some questions about timing and placement, it is clear that a serious line of storms will go through.

Tomorrow morning, before dawn, there may be some isolated or scattered showers and thunderstorms across the western half of the Houston metro area. However, the main event is likely to be a line of storms that forms northwest of the region and sweeps into the city. In terms of timing, we think this mass of storms will impact areas such as College Station around 5 am to 8 am, before pushing into central parts of the region (including the area inside Beltway-8/Sam Houston Tollway) between 8 am and noon. After this the line will likely continue down to the coast and exit the area to the east.

The models disagree on where the most impactful rains will be: Brazos County, Montgomery County, or Western Harris County are all possibilities, for example. But the bottom line is that we are going to mix a potent disturbance with an atmosphere with a lot of moisture. This is fertile environment for high rainfall rates, which can quickly back up streets and lead to flash flooding.

As a result of this we are elevating our flood alert to Stage 2 for areas along and west of Interstate 45.

Although we cannot entirely rule out other forms of severe weather, flooding is the main threat from these storms. Most of the region will likely pick up 1 to 4 inches of rain in a couple of hours, but there will almost certainly be higher bullseyes where 5 to 8 inches could fall in a very short period of time. In short, be prepared for disruptions to travel plans on Thursday morning, and be weather aware. We will have a full update for you early tomorrow morning.

In brief: Today and Thursday should bring the region our heaviest rains yet this month, with the potential for very high rainfall rates. We are concerned about the potential for street flooding, and have an ongoing Stage 1 flood alert for the entire region. We will monitor today for the need to escalate to Stage 2.

Overall pattern remains wet

The Houston region has experienced rounds of showers and thunderstorms on Monday and Tuesday of this week, but our confidence is increasing in the heaviest and most widespread rainfall arriving today and Thursday in the current pattern. It looks like the best chances for this will be during the morning hours on both days, so let’s dive in deeper to the forecast.

Wednesday and Thursday

Both of these days look to have a similar setup, and at this point probably will play out similarly. In the pre-dawn hours we will see a mass of storms develop to the west of the Houston metro area, and then this system will move through the city during the morning and early afternoon hours. In addition to the potential for heavy rainfall, especially on Wednesday there is the additional threat of damaging winds in Harris County and surrounding counties within stronger thunderstorms.

This morning, looking at the radar, we can see a large cluster of storms to the southwest of Houston, near Matagorda Bay. High-resolution modeling indicates that this mass of storms will move to the northeast, pushing through the Houston region from 9 am to 3 pm. This is the period when we are most concerned about lightning, street flooding, and damaging winds. In terms of storms, our weather may turn more quiet later this afternoon and evening, but there will still be the possibility of some sporadic flare-ups.

Similarly, on Thursday, a mass of storms will likely congeal west of the Houston area after midnight and then move into the city during the morning hours. Whether this occur before dawn, or during the mid-morning hours, it is difficult to say right now. But the overall threat remains the same: heavy rainfall and flooded streets, with lesser odds of damaging winds and other severe weather.

In terms of rainfall totals, they’re going to vary widely. I believe most parts of Houston and surrounding areas will pick up 1 to 3 inches. However, in these kinds of storms in the past, at this time of year, we’ve seen very high rainfall rates. So it would not surprise me to see locations with 5+ inches of rain over the next two days. Matt and I will be watching closely for the need to escalate to Stage 2 on our flood scale. We’re not there yet, but we’re concerned about some of the high-end rainfall rates. We will, of course, update as needed.

Mostly cloudy skies and rain-cooled air should keep temperatures in check over the next two days. I would anticipate highs in the upper 80s to possibly 90 degrees, with lots of humidity. Outside of thunderstorms winds should be fairly light. Nights will be warm and muggy.

Friday, Saturday, and Sunday

Each of these days will carry a healthy chance of rain showers, probably on the order of 50 percent or higher. But as of now we don’t see storms being quite as organized or intense—think pop-up storms rather than large systems moving through. As a result outdoor activities will probably be hit or miss. Days will see a mix of clouds and sunshine, and high temperatures will probably get into the lower 90s for the most part.

Next week

The pattern described above for this weekend should persist into Tuesday or Wednesday of next week: warm, muggy, with a solid chance of showers but probably nothing on the order of flooding. The second half of the weekend could go two ways: clearing skies and higher temperatures, or an ongoing wet pattern. I just don’t have enough confidence to predict one outcome or another.

A Galveston hurricane?

My daughters inform me that, on TikTok, “everyone” is talking about the possibility of a hurricane or tropical storm hitting Galveston next week. I won’t rule anything out during the Atlantic hurricane season, but suffice it to say in the world I live in, there is no model support for any such idea. So, probably not. I’m sure there is great weather forecasting on TikTok, but apparently the algorithm is feeding slop. Caveat emptor.

In brief: The rest of this week will see the potential for storms in the Houston region, and as of right now Wednesday looks to have the most widespread activity. Due to the possibility of heavy rainfall within stronger thunderstorms, and the cumulative effect of multiple rounds of rainfall, we have put a Stage 1 flood alert in place for this week.

Unsettled pattern

As we’ve been discussing on the site, Houston remains in a pattern where the absence of high pressure leaves us open to passing atmospheric disturbances. We will continue to see these systems sweep through our region every 18 to 24 hours or so, bringing a chance of widespread showers and thunderstorms. Not everyone is going to get hit with storms every day, but the threat of heavy rainfall and lightning is going to be part of our weather story at least through the weekend.

We can count on daily rain chances of 50 percent, or higher, through Sunday. Due to the potential for isolated flooding with each round of of showers, and the cumulative effect of all this by the weekend, we have put a Stage 1 flood alert into place until further notice. This is to cover the potential for (mostly minor) street flooding issues.

Tuesday

The radar is quiet this morning, and I expect things to likely remain quiet until around noon. However, after that there is about a 50 percent chance of showers and thunderstorms, with perhaps the best chances in the central Houston area and to the far north of the metro region: i.e. Conroe and points north. Skies will otherwise be partly sunny with highs in the low- to mid-90s. Actual highs will depend on the timing and coverage of the rainfall. Winds will generally be light, except in thunderstorms. Lows tonight will be in the upper 70s with a slight chance of rain.

There is a slight chance of “excessive rainfall” on Wednesday in our region. (NOAA)

Wednesday

High resolution models are indicating that a particularly potent disturbance will sweep through on Wednesday. I’d put rain chances in the 70 or 80 percent ballpark, with a slight risk for excessive rainfall. The timing is tricky, but right now the most impactful rains and thunderstorms are likely to fall during the middle of the day. Highs will probably top out in the vicinity of 90 degrees.

Thursday, Friday, Saturday, and Sunday

Overall the pattern is not likely to change much over the second half of the week, and into the weekend. Days will be partly cloudy, with highs in the vicinity of 90 to 93 degrees, with plenty of humidity. Each day will bring perhaps a 50 to 70 percent chance of rain, with isolated, strong thunderstorms. If you have outdoor plans, there’s a chance you can squeeze them in, as it certainly will not be wall-to-wall rain. But you probably want to have a backup plan.

Next week

This overall pattern now seems likely to extend into the middle of next week, perhaps through about Tuesday or Wednesday, before we see more sunshine and warmer temperatures, along with a diminution in rain chances.

In brief: Good afternoon. Matt and I have seen enough data to put a Stage 1 flood alert into place beginning today, and to remain place until further notice. In truth we can probably expire it Wednesday or Thursday, but we want to see how the pattern evolves before setting an end date.

Essentially, with high pressure having departed, the region now lies open to a series of disturbances that will bring rounds of showers into the region for much of this week. The first of these can be expected later this afternoon and into the early evening, and the next one after that by either late morning on Tuesday or into the early afternoon. Then we will continue to see the potential for additional rounds of showers, thunderstorms, and potentially severe weather (perhaps hail) for a couple of more days.

The threat level here is not super high. But with this Stage 1 flood alert we want to call attention to the possibility of intermittent heavy rainfall that may briefly back up streets and lead to some mobility issues. Not everywhere is going to see rain every day, or as every round passes through. However, with each passing system there are likely to be some pockets of heavier rain, and we want you to take a little extra time and care in such storms.

We will, of course, have a comprehensive update on all of this Tuesday morning.