Forecast temperatures ten thousand feet into the air whcih makes it easier to "see" where the coldest air is located at the ground. On Friday, it is likely over south central Canada and the Upper Midwest
Our first shot of cold air warms a little bit as it pushes east leaving much of the area seasonably chilly by the latter half of the weekend.
Our second shot of cold air arrives sometime on Monday. The southward extent of this cold air is currently unknown, but the current forecast keeps the coldest air in Canada. Temperatures in Minnesota though would still be well below average.
A reprieve from the winter-like air likely going into the middle of next week as a more mild Pacific air mass crosses the Rockies and enters the Upper Midwest.
The river of air at the top levels of the atmosphere, known as the jet stream, will dive southward Friday into the Ohio Valley. This allows very cold air locked up in Canada to surge southward and enter the northern U.S.
The cold air fans out a little bit across much of the northern U.S. making it a little less potent. However, the broad trough keeps our seasonably chilly air around through the weekend.
Another shot of cold air set for early next week and the jet stream tightens up and dips into the southern U.S.
By the middle of next week, temperatures are likely to start climbing again as the jet stream heads north allowing for a far more mild pattern for much of the U.S.