How likely is Minnesota to have a mega-rainfall event?

How likely is Minnesota to have a mega rainfall event?

Minnesota is 2.5 times more likely to have widespread heavy rainfall today than it did compared to before the year 2000. That's?according to officials with the Minnesota Department of Natural Resources, who call these?"mega-rain events."

MINNESOTA (FOX 9) - Minnesota is 2.5 times more likely to have widespread heavy rainfall today than it did compared to before the year 2000.

That's according to officials with the Minnesota Department of Natural Resources, who call these "mega-rain events." There have been 16 of these mega-rainfalls in Minnesota since 1973. 

Some mega-rain events, such as the recent floods in Texas, can be deadly.

What is a mega-rain event?

Big picture view:

Mega-rain events can be catastrophic, with the last one in Minnesota happening in 2020 near Mankato.

A mega-rain event is when at least six inches of rain covers more than 1,000 square miles within 24 hours, with at least one location receiving more than eight inches. That’s roughly the size of Hennepin and Scott counties combined. 

The Minnesota DNR says it's something they are always monitoring.

"It's hard to predict exactly where the next one will be. All we know is they do happen. They're fairly rare at any point on the landscape. But looking at an area the size of Minnesota, which is a pretty big area, you know, we've sometimes had two in one year," said DNR Climatologist, Peter Boulay. 

"Duluth has been hit by them. Northwest Minnesota has been hit and Rochester has been hit by them," Boulay added.

Mega-rain events in Minnesota

What they're saying:

Minnesota has had 16 of these mega-rains since 1973, but 11 of those have occurred since the year 2000. 

One of these was also responsible for setting the state 24-hour rainfall record, with more than 15 inches of rain falling on August 19, 2007, in Houston County, in Southeastern Minnesota. DNR Climatologist Peter Boulay explains why there has been an increase in these big rainfall events over the past 25 years.

"Because of climate change, we're seeing more rainfall. In general, more precipitation. Our rainfall amounts, as you look every 10 years, where we calculate normal for the Twin Cities, have been going up. So we're seeing an increased frequency of more rain overall," said Boulay.

How Minnesota tracks rainfall

Dig deeper:

The Minnesota Department of Natural Resources tracks all of this data with more than 200 gauges throughout the state, measuring rainfall as well as river and stream levels. 

All of these gauges have been around since 1973, which is why they use them as the starting point for this statewide study.