The ripening flood conditions have been caused by higher-than-usual snowfall and frost depths nearing 8 feet in some places.
"If the melt comes too quickly, we could see some pretty good flooding. It's still far away, but we see the conditions are laid out," said Steve Buan, the senior hydrologist for the National Weather Service's North Central River Forecast Center in Chanhassen, Minn.
The frost can cause problems because water will have trouble seeping into the ground, and that forces the runoff into the rivers, Buan told the Wisconsin State Journal. The frost is particularly hard, too, because of adequate moisture in the soil going into the winter. That makes it even more impenetrable, he said.
Unlike most years, there was not a warm stretch in January or February to help melt some of the snow.
He warned that cities along the Wisconsin, Rock, Fox, Pecatonica and other state rivers should prepare for flooding. The Portage area is the biggest concern because of an expected overload from melting snow in northern Wisconsin flowing down the Wisconsin River.
Heavy snow also covers southern Wisconsin, around the Rock and Fox rivers. And marshes and other areas that handle overflow from those rivers are already saturated from floods of the past few years, he said.
Another problem is when heavy ice in the rivers and streams breaks off during the melt and causes ice jams, which can cause flooding "in places where you're not expecting it," Buan said.
Flooding could also impact urban areas away from rivers. There is a potential for flooded basements, said Ken Potter, a civil and environmental engineering professor at University of Wisconsin-Madison.
Homeowners should move snow away from the foundations of their homes, especially if it has piled up significantly, Potter said.
"There's a lot of water that has to move. It's a little unprecedented," Potter said. "And if it can't move away from my house, it will end up in my house."
A forecast of warmer, rainy weather has led the state Department of Agriculture, Trade and Consumer Protection to ask farmers to avoid spreading manure over the next week because there's a high risk for it to run off into surface and groundwater.