Grab your waders, Minnesota, it's going to get wet.

If the weather turns warm and wet in coming weeks, flooding along the Mississippi River could reach levels not seen in the Twin Cities in more than a half century, a National Weather Service (NWS) meteorologist said Friday.

Speaking at a flood briefing in St. Paul attended by Sen. Amy Klobuchar and Gov. Tim Walz, meteorologist Dan Luna pointed to a map showing a 15 percent or greater chance of major flooding along the Mississippi, Minnesota, St. Croix and Red Rivers this spring.

"Just for a little context here, at St. Paul, there's a 15 percent chance we could see levels as high or higher than what we saw in 1965 — which is the flood of record," Luna said, before adding a note of optimism.

"We had similar numbers — not to get everybody alarmed — in 2013, and we had the perfect melt in 2013 so we never saw major flooding in most places."

That's the nature of flood forecasting. It's affected by air temperature, soil moisture, snow, rain and topography. But this year, it's a no-brainer.

Star Tribune, Star Tribune
The Sand Creek in Jordan has flooded its banks due to a large ice jam and cut off access to the Valley Green Trailer Park. This was the view of Syndicate Street with a few cars and trucks stranded in the water.

"We will see spring flooding. There is no doubt about it," Luna said.

A perfect melt occurs when temperatures rise above freezing during the day, then drop slightly below freezing at night to constrain drainage into the rivers, Luna said. If there's a fast melt, where daytime temperatures shoot into the 50s and drop only into the 40s at night, "most likely we will see flooding everywhere," he said. Add an inch or more of rain to that scenario and Minnesota could see "terrible flooding" statewide.

Luna said Minnesota is in the midst of one of the wettest decades ever. The state set a record for precipitation last year; the previous record was set in 2016.

Although a recent rainstorm and warmer weather have melted a lot of the snow, Luna said, the runoff is sitting on top of frozen ground with nowhere to go, and there's still between 3½ and 7 inches of water left in the snowpack.

Fortunately, the forecast for the next week or so looks favorable for a slow melt. Beyond that, forecasting lacks accuracy.

But even if Minnesota experiences ideal melt conditions for a while, Luna said, the threat of flooding will persist through April and possibly into May because there's so much snow on the ground across the river basins.

Guard ready to help

Friday's briefing was convened by the Minnesota Department of Public Safety (DPS). Besides Walz, Klobuchar and Luna, others attending were Reps. Betty McCollum and Jim Hagedorn; Col. Sam Calkins, commander of the St. Paul District of the U.S. Army Corps of Engineers; Joe Kelly, director of the DPS division of Homeland Security and Emergency Managment; Phil Hansen, CEO of the American Red Cross-Minnesota Region, Ceil Strauss, floodplain manager with the Minnesota Department of Natural Resources; and Lt. Gov. Peggy Flanagan.

Walz said that local, state and federal authorities are coordinating flood mitigation efforts, adding that he already has authorized the National Guard to be prepared to assist, if needed.

"We have never seen a winter like this one," Klobuchar said.

She said improvements have been made over the years on how state and federal agencies handle flood relief, but there still is a bureaucracy to wade through. A state must have $7.96 million in damages to trigger federal disaster aid, she said, and then each county must show damages of $3.78 per capita to qualify. If that happens, federal aid will pay 75 percent of the damages. If counties don't meet the threshold, however, they still might get state money, she said.

"We hope we won't be qualifying for federal funding because that would mean we don't have as much damage," Klobuchar added.

Kelly said the last time Minnesota had a major spring flood was 2011. At present, the state is mostly seeing localized snowmelt flooding, he said, but the main flooding event will come from the rivers.

The city of Jordan, for example, is dealing with an ice dam in a creek that backed up and prompted the voluntary evacuation Thursday of 300 households from the Valley Green mobile home park.

Officials were unsuccessful in removing the dam with a backhoe Friday, City Administrator Tom Nikunen said, but the dam seemed to be shifting late in the day.

"Like it or not, we're in the land of 10,000 lakes and every once in a while, the water turns on us," Kelly said.

The NWS Friday also reported minor flooding along the Zumbro River in Goodhue and Wabasha counties. Other areas experiencing minor flooding included the Cannon River in Northfield, the Redwood River in Marshall and the Cedar River in Mower County.

"The main problem has been ice jamming combined with the increased runoff we had with the rain and the snow melt over the last 48 hours," said Tyler Hasenstein, an NWS meteorologist in Chanhassen.

Other than that, the biggest problems Kelly said he's seen are township roads. Add a bit of rain, he said, "and they're mush."

Calkins said he declared a flood emergency on Monday, authorizing the Army Corps of Engineers in Minnesota to help where they're needed. He sent eight engineers out on the Red and Minnesota rivers. They also have gone to Stillwater, Afton and Winona.

The corps also has been draining reservoirs so they will have maximum storage capacity when the big meltdown arrives, which Calkins estimated would come sometime in the next two to four weeks. He said Minnesota towns are better prepared than ever to deal with a flood because they've put so much money and time into mitigation projects and training.

Staff Writer John Reinan contributed to this report. Dan Browning • 612-673-4493