Now that we are in December, we are entering the coldest couple of months for temperatures on average in North America. That means the lack of any sunshine around the North Pole allows the true arctic air to develop over the next few weeks. Well, as we know, every so often, this air is dislodged from northern Canada and heads south into the Upper Midwest. Well, it looks like that is about to happen for the first time this season.
Mild air will hang around the Upper Midwest into Thursday, but the first of two shots of cold air is expected. This first though is a glancing blow, which will drop temperatures a few degrees below average, but then are likely to quickly rebound over the weekend.
But then early next week, a much larger and colder surge of air can be expected as it comes straight out of far northern Canada and the Arctic Ocean just a day or two earlier. It will slide across snow-covered ground, which helps insulate it from any warming short wave or long wave radiation, allowing it to maintain its true Arctic characteristics all the way into Minnesota. This air mass will easily be cold enough to bring the first subzero readings of the season to the Twin Cities IF it indeed makes it this far south.
We will update the forecast as it closes in, but right now, I would expect a much colder week next week.