This map shows forecast temperature departures from average modeled by the American GFS. (WeatherBell.com)

The coldest air of the season so far is set to descend over the Upper Midwest and Great Lakes next week, with temperatures falling more than 30 degrees below average beneath Arctic high pressure.

Chicago could spend more than 80 hours below freezing, starting Monday night as the pocket of frigid air lingers overhead before relief finally arrives next weekend. Signs point to another potentially significant shot of cold toward the middle of the month.

The air mass responsible for the deep freeze is already consolidating over Canada’s Northwest Territories near the Beaufort Sea, 2,500 miles or more away from Chicago. Computer models depict an initial batch of cold arriving across the Northern Tier on Sunday before a reinforcing blast of cold sweeps south Monday night into Tuesday. Anomalous warmth will stream east ahead of the approaching cold front, helping cities like Washington, Philadelphia, Baltimore and Richmond hit 60 on Tuesday. Raleigh, N.C., could flirt with the 70-degree mark.

But well to the northwest, it’ll be a different story. Bismarck will first experience the icy burn Sunday, dropping below zero Sunday night with a hint of snow in the forecast. The chill will build Monday with highs in the teens. But that’s balmy, compared with Tuesday and Wednesday, when highs in the North Dakota capital won’t rise out of the single digits. “Overnight lows 10 to 15 below zero” are possible, according to the National Weather Service.


Lows predicted by the National Weather Service overnight Tuesday into Wednesday. (WeatherBell.com)

The cold front plows through the Twin Cities on Monday. Highs will be capped in the upper teens, with temperatures falling throughout the day and stiff northwesterly winds. Snow is also anticipated preceding the front, which could total three to five inches in Minneapolis by Monday evening. By Tuesday, the high temperature may be only 3 or 4 degrees, with lows more than 10 degrees below zero.

Minneapolis is no stranger to bone-chilling, bitter cold, so managing to snag a record low there is a challenge. But there’s a chance it could be done on Wednesday morning. The current National Weather Service forecast is minus-12 degrees. The record low for December 11 is minus-14, set in 1972. The city “could get within a couple degrees of record lows if we can clear the clouds out,” the National Weather Service wrote; that could allow for additional radiational cooling.

In Chicago, Tuesday’s high of 25 is forecast to be 20 degrees colder than the high Monday. Many locations will see a 20-degree swing in temperatures from Monday to Tuesday, as shown in the map below.


These are 24-hour temperature changes forecast by the National Weather Service. Many folks in the Midwest and across the Corn Belt will awaken Tuesday to temperatures 20 degrees cooler than the same time Monday morning. (WeatherBell.com)

Tuesday could feature the coldest night in the Windy City, at 9 degrees. That’s cold but nowhere close to a record. Record lows for this stretch of December are minus-10 to minus-15 degrees.

The cold will even bleed east into the northern Ohio Valley, although the air mass will moderate as it sloshes east toward the Appalachians. While upper 20s or lower 30s are possible in both Indianapolis and Columbus on Wednesday and Thursday, the cold will lose the bite it will have brought to places farther north and west.

Even so, the Interstate 95 corridor from Washington to Boston should see temperatures drop 20 degrees on Wednesday relative to Tuesday, where rain showers associated with the advancing Arctic front may change to a period of wet snow.

Milder air should begin to return to the freezer-burned areas of the north central U.S. briefly Friday and early Saturday.

Quickly thereafter, however, another shot of exceptionally cold air will surge down over the Dakotas and possibly the western Great Lakes. At more than a week in advance, however, confidence in the timing, placement and magnitude of the second wave of cold remains very low.