The chance of major flooding remains high along the St. Croix River and Mississippi River south of St. Paul, thanks to deep snowpack and cool spring temperatures, according to a National Weather Service flood outlook issued Thursday.
The report showed few changes from the forecast issued two weeks ago, with chances of major flooding slightly higher in Stillwater and Red Wing and slightly lower in St. Paul.
The forecast contained a bit of good news amid the alarms: Rainfall and temperature patterns for the next seven to 10 days should promote slow melting that could ease the flood threat, said National Weather Service meteorologist Craig Schmidt. The severity of any flooding will depend on what happens with rain and temperatures in April, he added.
The chance of major flooding fell to 47% in St. Paul and rose to 81% in Stillwater and 69% in Red Wing.
Sandbagging begins Monday in downtown Stillwater, where city crews have shut down riverfront parking lots in preparation for the construction of a dike stretching several blocks. The city has also closed the bike and pedestrian path across the Stillwater Lift Bridge.
In northern Minnesota, deep, wet snow threatens to create spring flooding across much of the region, the Weather Service said. The chances of major flooding along the St. Louis River at Scanlon were still relatively low at 10%, but that number could rise depending on temperatures and rainfall in the coming weeks.
If a home, basement or road in the Duluth area has flooded in past springs, it probably will again this year, meteorologists warned.
The problem isn't just how much snow Minnesota has gotten — it's how much water is in the snow, said Ketzel Levens, National Weather Service meteorologist based in Duluth.
"We've had very wet snow this winter," she said. "The amount of water in the snow is extreme; it's near a record high."
It's also staying on the ground longer than normal: There are still areas in the region with up to 46 inches of snow depth. The longer it stays on the ground, the more likely it becomes all that snow will melt at once under a heavy rain.
"It has to melt eventually," meteorologist Joe Moore said. "But the longer we put this off, the bigger the potential that it all melts at once."
One of the simplest things people can do to prepare is shovel snow away from the sides of a house or building before it melts, he said.
Red Wing has started to prepare sandbags and other barricades for some playgrounds and park areas in the flood plain. Fortunately, few homes in the city are at risk, said Lynn Nardinger, deputy public works director.
"We just don't have residential areas along the river here," he said. "The road to our water treatment plant can close and we'll have to boat out to it, but operations can continue."
Some of the city's roads closest to the Mississippi start to flood when water levels reach 14 feet. The river is all but certain to reach that high, according to the Weather Service. The flooding is predicted to be at its worst during the week of April 17.
"We're monitoring it and will plan accordingly and will decide on Monday how far we need to go," Nardinger said.
St. Paul has started to prepare its sewage and drainage systems for high water. City staff will start contacting homes and businesses in areas that typically flood first, spokeswoman Lisa Hiebert said.
If water levels creep up to moderate or major flooding stages, the city will build temporary levees and shut down roads if necessary. The first road to be shut down is almost always aptly named Water Street, Hiebert said.
"We're in the planning and monitoring stages right now," she said. "St. Paul is a river town and we are no strangers to flooding."