Record-setting snowfall in February across southern Minnesota has increased the risk of spring flooding.
According to the National Weather Service, there is an above normal flood risk for "the main-stem Mississippi River and some of its tributaries," with a "greater than 50 percent chance for flooding" along the Mississippi.
You can see in the map below, which is interactive on the National Weather Service website, there are six purple squares in Minnesota and numerous others just across state lines. They represent river locations that have a greater than 50 percent chance of major flooding this spring.
- Mississippi River at St. Paul - 65 percent chance
- Mississippi River at Hastings - 76 percent chance
- Mississippi River at Red Wing - 51 percent chance
- Minnesota River at Savage - 57 percent chance
- Cottonwood River at New Ulm - 70 percent
- Minnesota River at Montevideo - 66 percent chance
Flooding risks decrease when there is less precipitation in March and April along with a slower snow melt. The risk increases with more precipitation and a faster snow melt.
Playing into the increased flood risk is that the month of March is expected to have below normal temperatures, meaning we could go from cold to warm in a shorter period of time, which would lead to a more rapid snow melt.
Significant river ice and deep frost will also play a role in spring flooding threats, according to the La Crosse office of the National Weather Service.
Another key factor is how much liquid is in the snowpack, and the NWS Twin Cities reports that there is 3-6 inches of liquid in the snowpack around the headwaters of the Mississippi River, upper and central Minnesota River, and St. Croix and Chippewa rivers in Wisconsin.
"This is higher than we've seen recently, and in most areas is well above 'normal' for the end of February," the NWS Twin Cities says.