Dane Co. breaks state record for heaviest rainfall in 24 hours

Published: Aug. 21, 2018 at 6:10 AM CDT
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Rains in western Dane County broke a Wisconsin state record for heaviest amount to fall in a 24 hours period, according to the County of Dane Emergency Management.

"We talk about 100 year events normally, now what we're witnessing — hopefully, is a 500 year event and not more frequently," Madison Mayor Paul Soglin said at the Madison Water Utility Tuesday afternoon.

The National Weather Service in Milwaukee estimates the areas west of Madison could have received between 11 and 13 inches overnight on Monday into Tuesday morning.

"I don't think anybody envisioned the storm would get stuck over the western half of Dane County for as many hours as it did and give us, not just us — but the state a record rain. No one could have predicted that," Soglin said.

According to the National Weather Service, the previous record was 11.72 inches in a 24 hour period. That record was set on June, 24th 1946 four miles northeast of Mellen in northern Wisconsin.

"We've seen snowstorms. We've seen ice storms. We've seen tornadoes. Obviously, we've never seen a rain like this with so much damage. It's really important people understand how destructive flowing water can be, even if it's only a foot or 18 inches deep. It's so serious," Soglin said. "Its just amazing some of those cars made it through. There is nothing that cannot wait in terms of finding an alternate route and just simply staying put."

NBC15's Emily Blume met with the National Weather Service to find out what made Monday night's storm so unusual.

"It is definitely very difficult to predict more than 5 inches. But we were concerned and that is why we had out that flash flood watch," said Mark Gehring, lead forecaster for the National Weather Service in Sullivan. "We certainly didn't think it would be ten inches or more."

There have been multiple reliable reports of 15 inches in Cross Plains, said Gehring, who says the reports cannot yet be confirmed.

"Those aren't considered official sites for reported rain," Gehring said. "But it is very believable and we do believe it."

Because of this, the NWS can't announce a broken record — yet. It will take some time to get these measurements verified.

Note: Before any records are declared, there will be a thorough review of historical records on rainfall across...

Posted by US National Weather Service Milwaukee/Sullivan Wisconsin on Tuesday, August 21, 2018

The National Weather Service made this note about reporting records:

"Before any records are declared, there will be a thorough review of historical records on rainfall across Wisconsin. This could take a while to determine."

Record or near record one day rainfall for Wisconsin may have been broken just west of Madison. See graphic for details. This is a radar estimate of rainfall, so it is imperfect, but it is a good depiction of the heaviest rainfall areas. Detailed gauge reports will begin rolling in after 6 am this morning."

"If there's another rainfall, we have reason to be concerned because the ground is so saturated and the lakes are as high as they've ever been," said Soglin.

A release from Dane County Emergency Management states that Black Earth Creek hit a new record high flood stage.

Evacuations were underway throughout Tuesday in the Villages of Black Earth, Cross Plains, and Mazomanie. Black Earth residents are going to Heights Lutheran Church while residents in Mazomanie and Cross Plains are going to their community's respective fire stations, according to the release.