Today, We Passed the Record for All-Time Wettest May By a Wide Margin

At least if you go by the gage at my house. With six days left in the month, the Lake Houston Area has already broken the record for the all time wettest May. The official gage, of course, is at Bush Intercontinental Airport, but the NWS doesn’t release monthly data until the month is over.

This afternoon, my back yard rain gage recorded 17.24 inches for May. The previous record was 14.39 inches set in 1970. (See chart below.) That’s a 20% increase! With more rain on the way tonight and later this week.

From National Weather Service.

Effect on Area Streets

We also recorded 4.11 inches this afternoon in a four-hour period. That’s pushing the limits of storm drains. And predictably, people reported street flooding all over the area.

Ford Road in Porter on 5/24/2021 after 4 inches of rain in 4 hours. Photo courtesy of Nicole Black-Rudolph. Ford Road is one of the main evacuation routes from Kingwood when Northpark and Kingwood Drives are cut off by high water. Now upstream development is flooding it too.
Photo of street flooding in Atascocita, courtesy of Jennifer Zorn. Atascocita received more than 7 inches of rain in a 3-4 hour period.according to television news reports tonight. That qualifies as approximately a 50-year rain.
The City’s long-running sewer repair project in Kingwood Lakes has created a dam across the main lake, artificially raising the water level. Photo courtesy of Anna Mitchell.

Flash Flood Watch Till 9PM

A flash flood watch remains in effect for the Houston area until 9pm tonight. The four inches that fells this afternoon in about 4 hours rates as about a 5-year rain. Last weeks 5.5 inches in a little more than 3 hours was a 10-year rain. No wonder we’ve had the wettest May!

It’s important to remember that these statistics are averages. Just because you get a ten-year rain one week does NOT mean you are immune to another for 9.99 more years.

Effect of Five-Year Rain on Bens Branch

Before the recent rehabilitation project on Ben’s Branch, parts of this channel were down to a two-year level of service. Below, you can see how it handled a 5-year rain today. Room to spare. Quite an improvement for a maintenance project!

Looking downstream over Bens Branch toward Kingwood Town Center. Photo taken 5.24.21.
Looking downstream toward Lake Houston along Ben’s Branch.
Where Ben’s Branch crosses under Kingwood Drive, the City has yet to work out some kinks. Harris County Flood Control District does not maintain under City bridges. In fairness to the City, the Bens Branch rehab project was completed just last month.

Overall, ditches and streams in Kingwood seem to be within their banks.

Wider-Area Stream and Lake Report

However, warning signs are popping up all around the Lake Houston Area.

Harris County Flood Warning System 5.24.21 at 7PM.

At this hour, Lake Conroe seems under control. Luckily, the highest rainfall totals in the Lake Conroe area today were less than one inch.

But Lake Houston is approaching two feet above normal despite constant releases by the Coast Water Authority.

Posted by Bob Rehak on 5/24/21 with thanks to Nicole Black-Rudolph and Jennifer Zorn.

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