An unusual spring storm will bring moderate to heavy rainfall, wet snow, and cold temperatures to the Great Lakes, with higher terrain of western and north-central Upper Michigan expected to see significant snow accumulation.

A developing spring storm will impact the Upper Midwest from Saturday through early next week. The storm will bring periods of moderate to potentially heavy rainfall and moderate to potentially heavy wet snow into western and north-central portions of Upper Michigan.

Strong north gales are expected over western Lake Superior on Sunday, with the potential for high-end north-northwest gales to possibly storm-force gusts on Monday into Tuesday. Strong winds combined with below-average temperatures will make it feel unusually cold for this time of year. Wind chills are forecast to be in the 30s Friday and Saturday, dropping into the 20s by Sunday and Monday.

The expected snowfall amounts will vary depending on the location, but moderate to heavy wet snow accumulation is likely at times over the higher terrain of western and north-central Upper Michigan, northeast Minnesota, and Wisconsin. However, the higher spring sun angle and associated heating may limit accumulation during the daytime.

The combination of new rain and snowmelt of new and old snow will increase flood risk across northeast Minnesota and northern Wisconsin, including cities like Duluth, Minn. Runoff from the rain and snowmelt may result in rising river levels and flooding in flood-prone locations. A flood watch is in effect through Sunday evening.

The unusual aspect of this weather event is the timing, as it is happening during the spring season when such strong winter weather patterns are not as common. While snowfall in the Upper Midwest in late April is not unheard of, it is still considered to be relatively unusual. Typically, by late April, the region is experiencing warmer temperatures and the onset of spring, with most areas having already transitioned out of the winter season.

In fact, we’re getting close to the latest recorded date of accumulating snowfall for the region. For example, the latest recorded date of accumulating snowfall in Marquette, Mich., was on May 9, 1970, when 0.2 inches of snow was recorded.