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.

Thursday

At this point, we’d anticipate that whatever storms develop on Wednesday will again, to some extent, wind down Wednesday night. That leaves the question of where the best conditions for storms will set up Thursday. At this point, our best guess is they will develop somewhere to the south of Interstate 10, perhaps near the highway, or perhaps much further south. Frankly, it is hard to have too much confidence in any forecast, but certainly Thursday into Thursday night will likely be another wet period for some part of the Houston region.

Friday and Saturday

Unfortunately, our moist atmosphere isn’t going anywhere for the next several days. Forecast models have been suggesting that a somewhat stronger disturbance will push into the area later Friday and Saturday, likely leading to one final round of widespread heavy rainfall. As far as timings and bullseyes for the heaviest rain, sorry, we can’t help you there yet.

Overall, the National Weather Service is forecasting additional rainfall totals of 5 to 8 inches this week, with isolated areas of 9 to 12 inches through Saturday. These totals offer a reasonable guess, and are probably manageable for most areas if spread over the next four days. Unfortunately, for some locations (such as Kingwood and Sugar Land on Tuesday) these kinds of rains in May, with this kind of a moist atmosphere, often burst forth in just a few hours. So we expect more problems, and we’re going to be here with you throughout the next four days to try and stay on top of things.

Sunday and beyond

We still expect the rains to end by Saturday night or Sunday morning, giving us at least a day or two’s break from this, and some sunshine. It is not clear how long this will last, however, and given the uncertainty of the next four days, it seems like folly to try and confidently predict anything five to seven days from now.