How bad will spring flooding be in Minnesota? 5 key questions answered — and a silver lining

Rivers will rise across Minnesota next week as the snowpack piled up from one of the state's snowiest winters begins to melt in force.

By Tuesday, temperatures are expected to climb into the 70s in parts of the state. The warm-up, so soon after a late winter storm dumped more than a foot of heavy, wet snow, raises the likelihood of flooding in cities along just about every major river in Minnesota.

St. Paul preemptively declared an emergency as it plans for road and park closures along the Mississippi River; Stillwater has built a wall of sand that's 2,000 feet long and 6 feet high to keep its downtown safe from the St. Croix River; and Fargo, Moorhead, Grand Forks and other cities in the Red River Valley have started to plan sandbagging operations.

Here are some things to keep in mind about the flood risk this spring.

Why is the risk so high?

The short answer: snow.

This was one of the state's 10 snowiest winters on record, with high amounts in every river basin. The snow was particularly wet, too, holding an usual amount of moisture, especially in northern Minnesota. The cold spring kept it on the ground longer than normal, raising the risk that it would melt all at once.

The predicted warmup on Tuesday will hit the entire state at the same time, sending water into every river basin, said Craig Schmidt, hydrologist with the National Weather Service. That makes the risk particularly high in the state's biggest rivers, as more and more water from high tributaries feeds into them.

When is flooding expected to start?

The Weather Service still expects most rivers to crest in mid-April, but that could change depending on rainfall. The warm weather next week could also speed things up, Schmidt said. Smaller rivers will likely hit their peak as soon as the end of the week, while larger ones, such as the Mississippi River in the St. Paul area, may keep rising until late in the month.

What should we watch for?

Rain. Rivers will almost certainly be high, but adding any more precipitation over the next two weeks will compound the problem.

"We know we're going to have warm temperatures and we know we're going to have snowmelt that will put us in this flood threat," Schmidt said. "What would make it a really really bad flood would be adding rain to it at the wrong time."

The Weather Service expects skies across the state to be mostly clear over the next week, with chances of rain Wednesday in Duluth, Thursday in Minneapolis and Friday in Fargo.

Is anything working in our favor?

One of the few positives of the drought that lingered in Minnesota over the past two years is that most of the state has dry, thirsty soil ready to soak up quite a lot of water.

The heavy snowpack also kept the ground insulated from freezing temperatures. That's important because if the soil is frozen, it can't accept water. The thawed dry ground could help alleviate some of the worst of the flooding.

Is there a silver lining to this?

For the first time in two years, no parts of Minnesota are in severe drought. All the snow and water that's been raising the risk of floods has essentially erased one of the state's driest spells since the 1980s. The much-needed water will help alleviate stressed aquifers and trees, lakes and trout streams across the state.