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Cooler temperatures, lingering snow raises risk of flooding along Mississippi River, other waterways

Heavy snowpack in northern Wisconsin could cause moderate to major flooding if there's a sudden warm-up

Mississippi River flooding in Mississippi in 2017
Rogelio V. Solis/AP Photo

Lingering snow in northern Wisconsin and Minnesota could mean significant flooding along the Mississippi River and other waterways this spring.

The potential for flooding along the main stem of the Mississippi River is well above normal from Minneapolis down to Keokuk, Iowa, according to the National Weather Service’s North Central River Forecast Center.

Mike Welvaert, service coordination hydrologist for the forecast center, said current snowpack across northern Wisconsin and Minnesota is equivalent to 5-8 inches of water, with as much as 10 inches of water content in some parts of the northwestern corner of the state.

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“Once that water eventually melts, it’s going to be coming downstream and passing into the larger watersheds,” Welvaert said. “If it gets in at the wrong timing … we could be looking at the potential for water rising to levels we haven’t seen in quite a number of years.”

Cooler temperatures this spring have delayed the spring snow melt across much of the region. Welvaert said the prolonged warmup is similar to 2019, when many Mississippi River communities in Illinois, Iowa and Missouri saw major flooding.

“The longer we tend to linger with a heavy snowpack with a lot of water content, the greater the likelihood that at some point, we’re going to see temperatures jump up into the 50s and 60s,” he said. “Of course, throw rain on top of that … it could be a worse case scenario for generating a big flood.”

Welvaert said the best situation would be if temperatures swing above and below freezing, allowing melting during the day but refreezing at night to slow the water’s progress.

He said the forecast center is also expecting flooding along the St. Croix River this spring. He said officials are keeping an eye on the Wisconsin and Chippewa Rivers as well, which start in northern Wisconsin.

The potential for flooding in eastern and southern Wisconsin are at normal levels, according to the forecast center. Periods of warm weather over the last month has melted much of the snow in these areas. But wet soils mean there’s some potential for flooding in those ares if there’s precipitation in coming weeks.