Well, it’s over. The remains of Beta are crossing Galveston Bay this morning, and with all of the storm’s heaviest precipitation far to its east, we are done. Houston should begin to see some rather fine weather later today and Friday, on the backside of Beta with a northerly flow. And then, while we cannot absolutely promise this, our confidence is fairly high in a robust, fall-like cool front arriving in about one week’s time. Before the forecast, however, I wanted to share a few quick thoughts about our not so dearly departed tropical storm.

It could have been much worse

Let me tell you, if you would have told me a tropical cyclone was going to make landfall about 120 miles down the coast from Galveston, in mid-September, I could envision all manner of nightmare scenarios.

But we had two big allies over the last week; moderate wind shear to prevent Beta from strengthening, and dry air over the state from a weak front that disrupted its circulation and prevented the formation of several, thick bands of rainfall. Instead, if you watched the radar closely, there was only ever really one strong band that was perhaps 10 to 15 miles across. This just happened to set up over Houston on Monday and Monday night, hitting the communities of Friendswood, Pearland, Sugar Land, and more.

Here is a map of the three-day rain totals that show this narrow corridor of 10 to 16 inches of rain over south and southwest Houston. The vast majority of the rest of the upper Texas coast saw 6 inches of rain, or less, from this storm.

While Beta was not as long a duration event as Hurricane Harvey (which, by the way, dropped 40-60 inches of rain over much of the area in yellow and green above), three days of potentially heavy rainfall is a long time. Slow-moving tropical systems are no joke. With Beta, not only was there just one main band, but its rainfall rates were not particularly high. I believe this was due to dry air, but I am not sure and will look forward to a post-storm analysis. In any case, we generally saw rainfall rates of 0.5 to 1.5 inches under this band, with a few exceptions, versus rates of 3 to 6 inches that tropical storms often produce.

We have not done nearly enough

Three years have now passed since Harvey, and a tropical storm that we discussed above as pretty moderate, brought the area’s flood systems to its knees. Only the Clear Creek watershed south of Houston, which received 7 to 16 inches of rain across much of its extent, really flooded in a significant way. But a lot of other bayous, like White Oak, Cypress, Buffalo, came up to the top of their banks or briefly spilled over them. A tropical storm that brings a range of 5 to 15 inches rain across Houston, with rainfall rates below 2 inches per hour, is a fairly common event. We will see more like this, and more that are much worse in years ahead.

I know the community has done some nice things, like work on Brays Bayou, since Harvey. But it is not nearly enough. Local, state, and federal officials need to work together to develop and implement a broader flood management plan. I know that is difficult in our nation’s political climate, but the desirability of living in Houston is at stake. Who enjoyed the stress about flooding over the last three days?

I missed Matt

Matt’s wife delivered a son early on Sunday night, so I was flying solo on the site for a couple of days amidst the height of the storm. It sure made me value the fact that I normally have someone to share the load with, and talk through the forecast. Clearly, we need to chain Matt to his desktop when future inclement weather threatens.

Houston’s forecast

There is not a whole lot to say about our weather ahead. All heavy rainfall from Beta has exited the area, and by this afternoon we should start to see some sunshine across Houston. High temperatures will probably get to around 80 degrees. All of the bayou flooding issues we’ve seen, including Clear Creek, should end by this afternoon. Northerly winds will bring slightly drier air into the region, so temperatures tonight may drop into the upper 60s tonight.

Friday and the weekend

The weekend looks outstanding for late summer. I think we can generally expect lots of sunshine, highs ranging from the mid-80s to 90 degrees, and lows around 70. It will be humid, yes, but not as humid as it can get in Houston. We’re definitely entering the end stages of summer in Houston. Rain chances remain low.

Next week

This warm, but not too warm trend will likely continue until about Wednesday of next week when there is fairly good agreement among the global models in a cold front passage. Since this is still a week away it remains too early to say definitively that this will happen, but the signal is pretty strong, and the overall flow pattern in the atmosphere is supportive. I think at least part of the Houston region will have a good shot at lows in the 50s during the second half of next week.

10:15 pm CT Tuesday: The remnants of Beta are continuing to trudge toward the east-northeast, and that’s good news for the greater Houston area. The strongest, outer band has already moved well east of the city, and now lies mostly north of Harris County. And it should keep right on going thanks to Beta’s progressive movement.

We’ve seen some strong storms this evening that have dropped 2 to 5 inches of rain over north and northwest Harris County, including areas such as Cypress Creek. This has brought the creek to near bankfull at some locations. But these storms appear to be moderating somewhat, and slowly lifting out of the area. The heaviest rains are now moving into areas such as The Woodlands, Kingwood, and Liberty that have largely been untouched, heretofore, by Beta’s heavy rains. Some of these locations may pick up 2 to 4 inches, but that’s probably about the top end of things tonight because the storms seem to be moving through at a reasonable clip.

There is a secondary circulation near Beta’s center this evening, and this is producing some light to moderate showers over Pearland, Sugar Land, League City, and other areas hard hit by Beta on Monday night. However, we have no expectation that this inner circulation will “blow up” as it moves through these areas and into Houston. These storms may put down a few tenths of an inch of rain, perhaps as much as one inch in a few areas, and then move on.

Generally, we still expect any heavier rain to move east of Interstate 45 by around midnight, or shortly after; and for the messy stuff to move beyond Harris County by around sunrise on Wednesday. From there the focus moves into East Texas, where places like Lumberton or Silsbee may see some very heavy rain on Wednesday morning. We are close to the end of this one, folks, and damn if it doesn’t feel good.

Our next post will come on Wednesday morning, after I’ve had some sleep.

4 pm CT Tuesday update: We’re starting to get a better handle on the forecast for the rest of today, tonight, and Wednesday when it comes to the potential for heavy rainfall. The good news is that we’re reasonably confident that this mess will begin to clear out of here by Wednesday morning, if not sooner for some areas. The bad news is that we’ve got to get through later today and tonight.

Beta synopsis

Beta is now a depression, with sustained winds of 30 mph. In its 4 pm CT advisory on the system, the National Hurricane Center notes that its speed to the northeast has increased a little bit today, from about 2 mph to 5 mph. This speed should increase further over the next 24 hours. The storm’s “center” will pass across the Houston area on Wednesday, probably before noon. Its passage should be imperceptible.

Tuesday evening and Wednesday morning

As anticipated, the radar cleared out over much—although not all—of the Houston metro area earlier this afternoon providing a reprieve for southern regions after more than a full day of rain. Aside from Clear Creek on the southern side of Houston, most bayous are within banks at this time. The Clear Creek watershed, by contrast received some of the heaviest rains and some home flooding in Pearland and Friendswood has been reported today. Based upon current levels, it looks like flooding along Clear Creek can be classified as a 10-year flood, although that will have to wait for a post-storm analysis.

As the remains of Beta move northeast, we anticipate the storm’s circulation will draw additional moisture in from the Gulf of Mexico, and form new rain bands. These will likely produce training over the region (at 4pm CT we’re seeing this from downtown Houston up Highway 290). Most model guidance suggests 2 to 6 inches of rain over these areas, but the National Weather Service has indicated a risk of some areas seeing 10 inch bullseyes.

At this time it appears the heaviest rains tonight will probably miss hard-hit areas in Fort Bend, Brazoria, and Galveston counties—they may go further north. However, it’s going to be close. For example, and take this with a grain of salt, here is a 12-hour rainfall forecast from the HRRR model showing accumulations from 4pm Tuesday through 4am Wednesday.

Beta is a messy storm and unpredictable, so this is just one forecast and far from gospel. Still, this model (and others) indicate the heaviest rains during the next 12 hours will probably stay north, and current radar trends support the idea that high rainfall rates will be most prominent across north, northeastern Harris County and into Liberty County.

Were such rain totals to come further south into Harris County they would pose a big risk to areas like Meyerland and Westbury, which have recorded in excess of 10 inches of rain over the last 24 hours. However, we have seen some good falls in Brays Bayou today which are continuing. So a few inches, which is our current expectation, are probably manageable, but 10 inches would be pretty bad.

As Beta continues to slog to the northeast, most model guidance shows the precipitation exiting the western half of the metro area by around midnight, or the wee hours of Wednesday morning; and exiting Harris County by around sunrise or shortly thereafter. By the middle of Wednesday morning the focus of heavier rainfall will probably shift toward the Beaumont area. So it looks like we have about 12 to 18 more hours to battle with Beta. Is anyone else sick of this storm?

Our next update will come by or before 8 pm CT Tuesday.