Updated: 4:30 p.m. | Posted: 11:50 a.m.
National Weather Service forecasters said Thursday the risk of major spring flooding is increasing across Minnesota.
The flood threat has risen in the past two weeks, as snow on the ground increased to near historic highs.
"The main story, here, is the above- to much-above-normal flood potential across southern Minnesota, Wisconsin, Iowa, Illinois, Missouri and extending down the Mississippi River," said North Central River Forecast Center hydrologist Corey Loveland.
This winter's heavy, wet snowfalls — including more in the forecast this weekend — piled on top of already wet and frozen soil has increased the risk.
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Outlooks like the one released today compare this year's conditions to those of past years. Forecasters then develop a range of flood risks based on previous experience and what might happen in the next few weeks. It offers them a general, early picture of potential flooding risk.
Flooding potential depends largely on how fast the snow melts.
But Loveland added that cold temperatures forecast for March are likely to delay the spring snow melt in Minnesota, making the region vulnerable to future storms and a rapid warm-up in temperatures.
The National Weather Service will begin issuing specific flood forecasts once the snow melt begins.
Add central and southern Minnesota and western Wisconsin to the snow-packed regions where forecasters are warning of possible spring flooding.
The weather service estimates at least a 50 percent chance of major flood stage on the Minnesota, Crow, St. Croix and Mississippi rivers.
The Mississippi threat is from St. Paul southward.
The flood risk is rising across southern Minnesota, because of heavy snow and the likelihood of a late spring snow melt.
The weather in February, Loveland said, didn't help.
"Due to the very wet and or high water content conditions, the region is pretty vulnerable right now to future storm systems and of course any rapid warm up in temperatures," he said.
Western Minnesota and the Red River Valley
Forecasters say the threat for major spring flooding is increasing in the Red River Valley of North Dakota and Minnesota, where the neighboring cities of Fargo and Moorhead have been on alert since a record flood 10 years ago.
The National Weather Service says there's a 50 percent chance the river will reach 35 feet in Fargo-Moorhead, which is considered major flood stage. That's up 4 feet from the last flood outlook issued in February.
The two cities have taken several measures such as home buyouts and levees since the record flood in 2009, when the river crested at about 41 feet and the cities were protected by a massive sandbagging effort.
So while flooding along the Red River could be significant this spring, it will also likely be manageable for most cities along the river.
Elsewhere in the Midwestern plains
Officials say extremely wet conditions throughout the Missouri River basin means an increased risk of flooding.
The U.S. Army Corps of Engineers said Thursday that it expects 112 percent of the normal amount of runoff water to flow into the Missouri River reservoirs this year. The full flood storage space is available in those reservoirs.
Several rivers in South Dakota and Iowa below the Gavins Point Dam have a higher risk of flooding this spring. The rivers with higher flood risks include the James, Big Sioux, Floyd and Little Sioux rivers.
Iowa officials say they have prepositioned pumps, sandbags and other flood-fighting equipment throughout the state, so they can be ready to respond quickly to flood concerns.