I have to admit, I enjoyed Eric’s somewhat euphoric post at midnight. Though as the parent of a toddler and infant that slept — how can I say this? — poorly, for lack of a better word, it was a long night. I’m sure many of you with kids and pets can relate!

But seriously, although it was a wild evening, the city of Houston and most of the metro area are doing fine this morning.

Flood Scale remains Stage 2

That said, I am going to hold our flood alert at Stage 2 out of an abundance of caution. Based on model data, I think most areas north of I-10 are realistically down to Stage 1 concerns going forward, as most rain is projected to fall south of I-10 today. Given some heavier rains already this week south of Houston (and east of Houston), I just think we should hold at Stage 2 and watch the next cluster of storms later this morning and afternoon that may graze those areas, and just make sure tonight looks to avoid anything serious in Houston. Forecasting this has been and remains tricky, and as expected, the evolution of the storms has not gone quite as modeling suggested even 1 to 2 days ago.

The NWS intends to keep Flash Flood Watches going through midday Thursday for the entire area.

Water levels

A look at the Harris County Flood Control map of water levels as of 6 A.M. shows only a handful nearing bankfull or out of their banks.

Expect just some minor lowland flooding in spots.

We will need to watch some primary river levels in the coming days, particularly southwest of Houston (though the Brazos looks to remain below flood stage in our area for now), as well as the Trinity River east of the city, which is currently forecast to approach major flood stage at Liberty by the weekend.

This would yield significant lowland flooding and some house flooding potentially as well. We’ll keep you posted on this, as there could still be some changes to river forecasts as the future rainfall forecasts are revised.

Today

Rain continues in the Houston area this morning, but it’s falling at the rate of about a quarter-inch or less an hour. That is manageable and should not cause any additional serious trouble.

Our attention will focus to another cluster of storms developing over Mexico this morning. The good news is that this seems to be lined up to stay well south of virtually the entire Houston area. We’ll probably see rain or showers continue through mid-morning, and there will continue to be a chance of showers through the afternoon. But any organized, heavy rainfall likely stays well south of Houston.

The Weather Prediction Center arm of NOAA continues a moderate risk of excessive rainfall, essentially from I-10 south to the coast. And this may even be skewed a bit far north given trends on models this morning. The biggest problems will most likely be from Matagorda County south past Corpus Christi. But if current trends hold, even Matagorda County may not be too bad. But they have seen 3 to 4 inches of rain since midnight south of Bay City.

Tonight and Thursday

The good news is that it appears that models have tapped the brakes a bit on significant, widespread heavy rainfall in this timeframe. That doesn’t mean it won’t rain. It also doesn’t mean we’re entirely out of the woods with respect to flooding risk. But at this point, there seems to be a lack of model data arguing for serious rainfall tonight or tomorrow.

So, let’s call it a chance of showers and thunderstorms at virtually any time tonight or tomorrow. If a storm does develop it will be capable of producing heavy rainfall. But at this point we don’t expect significant, widespread rainfall. We’ll continue to monitor for any changes.

Friday

There are some indications on models that the atmosphere may recharge a good bit by Friday, with more available atmospheric moisture. This could lead to another round of heavy rain and storms, but details are fuzzy. This might be a period to keep an eye on though. Improving conditions will arrive this weekend.

Eric will have our next update before 2 P.M.

A ferocious line of storms roared through Houston on Tuesday night, producing a biblical amount of lightning, threatening with tornadoes, throwing down some hail, and dropping buckets of rain. But there was a silver lining—a silver lining that if I’m being honest I did not fully anticipate—with these storms. Rather than slowing to a crawl as they moved into Houston, these storms kept right on trucking. Yes, the storms produced intense rainfall rates as high as 4 inches per hour, but as the heaviest bands of rainfall kept moving on there simply was not enough time for serious flooding.

Can I get an amen?

Seriously, I’m not sure I’ve ever been so happy to observe a radar absolutely lit up by bright red hues, indicating intense rainfall rates, as I was tonight. Because those storms kept on moving through. Instead of slow-moving storms that trained over our areas, we got a freight train. Choo-choo!

If I sound a bit loopy tonight it’s because I’m just so tired of writing about horrendous floods in Houston. Tax Day floods. Memorial Day floods. Halloween floods. Hurricane Harvey. Tropical Storm Imelda. Beta. It goes on, and on, and on. So tonight it feels amazing to write that Houston did not flood. I can write that this line of storms, which could have been very, very bad for the region, was by-and-large not bad. We had an hour of fire and brimstone, most everyone got 1 to 3 inches of rain, and then this system moved along.

So what comes next? The rainfall and threat of severe storms is moving to the east, and offshore, for the night. Some light to moderate rainfall may persist across Houston during the overnight hours, but this will not pose a significant flooding threat. Going to work, school, or other activities on Wednesday morning should be fine.

It looks as though we may see some additional rounds of showers and thunderstorms coming through later on Wednesday, after the atmosphere has a chance to recharge, and then again on Thursday. Given that I still have some slight concerns about areas just east of Houston on Thursday, I’m going to leave our flood scale alert at Stage 2 for now. But given more data by the morning we may be able to ratchet that back a bit. Matt will have an update by around 7 am or before on Wednesday.

Storms are absolutely hauling their way into the Houston area tonight, faster than most of us expected earlier today. Good news, as you’ll see below. But they are intense. Rain is falling at a rate of 3 to 4 inches per hour on average in that intense red portion of the line bowing across Rosenberg, Cinco Ranch, and Cypress at 9:45 P.M.

These types of rain rates will almost certainly produce street flooding across many parts of the region through Midnight, spreading east and south.

In addition, there have been multiple tornado warnings issued with these storms, including one storm that may have well produced a tornado just north of Brookshire earlier. Stay alert and aware, and seek shelter if a tornado warning is issued in your area. As of this writing, there is a tornado warning for the northwest side of the city through 10:15 P.M. Even with no tornado, strong, damaging winds are possible.

Strong winds of 55-66mph along this entire line. Seek shelter in an interior room #houwx #txwx pic.twitter.com/sVrvNO6PGL

— Jeff Lindner (@JeffLindner1) May 19, 2021

So, some good news about all this at least: That the storms are moving quickly is positive because, while it’s going to rain much of tonight, the super-intense, “floody” 2 to 4+ inch per hour rates will be short-lived over a given area. We can manage a steady rain. It’s when you get that overly intense stuff for more than an hour or two that things get out of hand.

Beyond tonight? Truthfully, I don’t have a great feel on what to expect tomorrow at this point. I think some of that will depend on how these storms evolve over the next several hours, and what happens back to our west overnight. Some models redevelop storms in parts of the area. Others give us a nice break between storm chances. It’s a tough call right now, so you’ll need to be fairly flexible and adjust with the forecast tomorrow. We do know that there will be more storms, but how intense and exactly where they hit matters a lot, and we just aren’t sure yet.

Eric will have an update on what’s happening here after midnight tonight.

Ok everyone, take a deep breath. The greater Houston region has experienced a nice reprieve from heavy rainfall today. That’s the good news. The bad news is that our atmosphere has recharged, and we are about to experience the worst of this potential flooding evening tonight and on Wednesday. The timing of all this remains in flux, but what follows is our best assessment for now.

Tuesday night

A pretty serious block of showers and thunderstorms are massing just to the west of Houston this afternoon, and we expect them to move toward our region this evening and during the overnight hours. These storms are being juiced by a slow-moving upper-level low pressure system, and they will have plenty of moisture to work with tonight.

We think most of Houston and the surrounding counties will see 2 to 5 inches of rainfall between now and sunrise on Wednesday, with higher isolated totals. These storms will be capable of producing intense rainfall rates above 2 inches per hour, which will quickly back up streets. Almost certainly some part of our region will see 10 inches of rainfall, or more, during the overnight hours. For now we are maintaining a Stage 2 flood alert, but this threat may need to be adjusted upward later this evening.

Although rainfall is the primary threat, some of these thunderstorms may bring severe weather as well. The National Weather Service has published a tornado warning that will remain in effect for the western half of our region until at least 9 pm CT tonight.

Wednesday

It looks like tonight’s storms may work over the atmosphere, and if this happens we would expect to see a break in storms on Wednesday morning, possibly lasting into the afternoon hours. After this point it’s really difficult to say what will happen with confidence, but I think it’s reasonable to expect another round of storms Wednesday evening or during the overnight hours. Where this sets up, and whether it’s as intense as Tuesday night, is something I just don’t really feel comfortable predicting.

Thursday and beyond

We think the focus of these storms will begin to swing eastward on Thursday. For the overall event, most areas will probably see an additional 4 to 8 inches of rainfall, on average, from now through Thursday. This means some areas will see more, and it is in those locations we are most concerned about flooding.

The map below shows NOAA’s best guess for rain accumulation totals from now through Thursday night, but this should not be taken as gospel.

Matt and I will be continuing to work this event, and will update again by around 10pm CT Tuesday night.