By several measures, Tuesday’s rains were exceptional for parts of the Houston metro area. According to the Harris County Flood Control District, one gauge in Sugar Land recorded 5.16 inches of rainfall in 1 hour and 15 minutes, and multiple other parts of the city saw rainfall rates nearly that extreme, which will quickly overwhelm the capacity of urban roadways. Tuesday’s commute was an absolute mess. Moreover, unofficially, an estimated 400 homes flooded in Kingwood. The Brazos River at Richmond has already reached a minor flood stage. Because of the unexpected intensity of Tuesday’s precipitation, and the potential for more heavy rainfall over the next four days, we are raising the expected impacts from these storms to Stage 3 (out of five levels) on our new flood scale.

Fortunately, the storms finally died down between 9pm and midnight on Tuesday, allowing the area a reprieve during the overnight hours. This allowed several creeks and bayous near the tops of their banks to begin receding, although many remain higher than normal. So let’s discuss what happens next.

Wednesday

The unstable, very moist atmosphere that produced widespread heavy rainfall on Tuesday more or less remains in place today, and this should fuel at least some scattered showers and thunderstorms throughout the daytime in the city. We do not believe these storms will be as widespread as on Tuesday, but certainly with some of the more slow-moving systems some areas could pick up a quick 1 to 3 inches of rainfall. Overall, however, most of the city will probably receive less than 1 inch of rain today.

Our other concern stems from an upper-level disturbance and cold front now bringing storms to west and central Texas. This should move toward the region this afternoon and evening, bringing with it the potential for severe thunderstorms toward Houston. While most of the action will probably remain north of Houston, NOAA’s storm prediction center has brought the region where there is a “slight” chance of damaging winds, hail, and potentially tornadoes down to about the Interstate 10 corridor. This will be worth tracking.

Basically, today is a day of “potential.” The unstable atmosphere could produce a very wet day, almost like Tuesday for some areas. Or showers could be much more scattered in nature—our high resolution models have performed so poorly of late it’s just hard to say for sure. Similarly, the upper-level disturbance could remain far enough north of the metro area such that it will not cause major problems—or not. We’ll be monitoring throughout the day for you.

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Earlier, we posted that we expected the heavy rainfall to wane between 6pm and 9pm this evening. Unfortunately, the storms have sustained themselves as the sun has gone down and continued to pile on rain totals—especially to the southwest of Houston in areas such as Sugar Land and Richmond. Regions there have now recorded 8 to 10 inches, nearing the exceptional amounts recorded in Humble and Kingwood earlier today and this afternoon.

So what happens now? With the sun now falling below the horizon, the rain cooled atmosphere will have less energy to sustain itself, and from a pure physics point of view, these heavy rain showers really should really ebb over the next 3 to 6 hours. But it is hard to have overly much confidence in this forecast given how much we’ve missed already today. We’re hoping for a break later tonight and perhaps Wednesday morning.

Where does this leave us? Quite frankly, we didn’t anticipate that the rains would be as intense as they were today. Certainly, we didn’t expect 10 inches of rain for any part of metro Houston, nor the need for high water rescues as are presently ongoing in southwest Houston. Yet here we are on the first day of a multi-day event, with soils now thoroughly sodden; some bayous near bank full; river concerns; and more.

Forced to guess, I’d say we’ve got two more major rounds of storms to worry about after this evening. There likely will be widespread showers on Wednesday night and Thursday, and then some kind of mess on Friday and Saturday. If those rounds are as bad as we’ve had today, then we’re going to see a much worse situation than now, but I don’t think we can quite say that yet.

We’ll be back with a full report in the morning.

It’s been a day in Houston, with some very heavy rainfall across parts of the city. If you live in Kingwood, congratulations, so far you’re the big winner with about 6+ inches of rain. With lots of street flooding in the area, it’s a mess trying to get home this evening along I-59 north, as well as I-59 south toward Sugar Land.

Most of the high-resolution model forecasts indicate that the current widespread activity should die down this evening, by 6 to 9 pm, which should coincide with the loss of daytime heating. From that point on, we will hopefully see a reprieve from heavy rainfall during the overnight hours.

Wednesday is a bit of a crapshoot. There is a scenario, which I’d probably lean toward, that keeps most of the heavy rain away from Houston as a cold front remains north of the metro region—including away from Kingwood and surrounding areas hard hit on Tuesday. But frankly, given the intensity and widespread nature of the storms Tuesday I don’t have great confidence in the forecast for Wednesday. Hopefully the forecast is a bit more clear in the morning.

From now through Saturday it’s going to be a day-to-day thing.

The radar is mostly quiet this morning across the region, but that will soon change with the onset of showers and thunderstorms later today. From there on we will enter a very wet, and somewhat unpredictable period, during which rainfall should peak from Thursday evening through Saturday. Below, we do our best to assess this mess, and use our new flood scale for the first time.

Tuesday

Generally, we expect rain showers and thunderstorms to develop south and west of Houston this morning, and then migrate north of I-10 later today. But admittedly, that is just a guess. The high-resolution models we use to predict the development of these small-scale storm systems have been failing us of late, so we don’t have great confidence in these storms. Accumulations of 0.5 to 1.5 inches are possible for some areas today, while parts of the region are likely to see no rainfall at all. Highs will only reach about 80 degrees. Lighter rain will be possible Tuesday night, but most of the region should see a break.

Wednesday

The weather story for Wednesday will be the propagation of an upper-level system across northern Texas, which will drive the potential for severe weather over parts of Texas, including Austin, and East Texas (see map above). It remains to be seen how close these storms come to the Houston metro area, but Waller, Walker, and Montgomery counties could well see damaging winds and hail in addition to 1 to 2 inches of rainfall. Southern parts of the Houston region may not see too much rain Wednesday.

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