Another large winter storm is set to impact the Plains, Midwest and Great Lakes this week. Significant accumulating snow across the Plains and Upper Midwest, to the threat for ice and sleet accumulations in the Great Lakes, and even thunderstorms to the south can be expected. Locally, it’ll be a mix of rain, freezing rain and sleet that’ll move in Wednesday afternoon and evening.

The timing of the storm has not changed too much from previous thinking: Light flurries/snow moving in near the state line late Tuesday evening, pushing north into Wisconsin by Wednesday morning. A brief break in precipitation Wednesday morning will be followed by what will most likely be rain showers mid to late morning, possibly mixed in with a little sleet and freezing rain. By the afternoon, we should begin to see more of a freezing rain, sleet, and rain mixture. Locations closer to the state line may see more freezing rain and sleet, while locations further south may see more rain and freezing rain.

There is a lot to look at when trying to forecast exactly what precipitation type will fall, and where. Warm air moving in just above the surface will be enough to completely melt anything frozen falling from the clouds. Temperatures at the surface, however, are going to be key. A shift in a degree or two could mean a big difference on whether or not your afternoon commute is icy or just a cold rain.

It still looks like the greatest risk for the rain, freezing rain and sleet mixture will occur from near Monroe to Janesville, south towards I-88. South of there, heavy rain is possible. Ice accumulations of over a tenth of an inch may occur, especially by Wednesday evening. Prolonged periods of freezing rain could cause accumulations to reach a quarter of an inch. The risk for that, at this moment, appears to be low. Should any significant icy take place Wednesday evening the threat for power outages would increase due to gusty northeast winds.

The majority of the mixed precipitation comes to an end Thursday morning, although there may still be some lingering through the morning. West/northwest winds will be increasing throughout the day.