Late season storm targeting Wisconsin, Minnesota

More than a foot of wet snow is headed for southern Minnesota Friday into Saturday. But, other areas of the Midwest are targeted as well. Heavy 4-8” totals are predicted to extend into sections of southern and central Wisconsin. Low dewpoints, indicating exceptionally dry low level air ahead of this storm, present a forecast challenge. As precipitation falls into a layer of such dry air, it evaporates—a process known as evaporative cooling. Many a March storm has produced accumulations south of the area initially predicted despite above-freezing temperatures at the start. Rain may arrive in the Chicago area late Friday. But, precip is to mix with or change to wet snow near the Wisconsin line toward morning, then continue as snow or a rain/snow mix Saturday. Should this switch occur sooner or farther south, snowfall could cover more than just the northern half of the metro area.