An outbreak of Arctic air is likely to bring bitter cold temperatures to the central United States by early next week, before plowing east midweek.
Temperatures may drop to levels at least 20 to 30 degrees below normal in parts of the Montana, the Dakotas, Minnesota, and Great Lakes between Monday, Dec. 9, and Wednesday, Dec. 11. This means subzero cold in many areas, and even lower wind chills.
To the east, temperatures are likely to take a big and sudden plunge Tuesday and Wednesday as the Arctic front sweeps through, but the shot of cold will be somewhat less intense compared to areas to the northwest.
That Arctic front will bring the first wave of chill late Sunday into Monday across the northern Rockies, High Plains and Upper Midwest, paving the way for reinforcing blasts of cold to sweep down from the icy Canadian prairie.
The core of the piercing cold will likely focus between central Montana and Wisconsin.
Great Falls, Montana, likely won't escape the 20s on Sunday, while Glendive looks to hold in the 20s Monday through Wednesday at least. Snow is likely preceding the cold Sunday and Monday.
In Bismarck, North Dakota, there's nothing to fend off the cold. The Peace Garden State's capital is forecast to plummet below zero Sunday night, with highs struggling to reach the teens on Monday and single digits Tuesday. Overnight lows could be 5 degrees or more below zero. According to the National Weather Service, "wind chills may approach 20 to 25 below at time."
It's a similar story in Sioux Falls, South Dakota, Monday and Tuesday nights could approach or dip below zero, with highs in the teens.
For the Southern Plains, it's a question of whether the initial shove of cold air has enough oomph to push all the way down to the Texas and Oklahoma Panhandles. However, odds are that temperatures won't make it much above the upper 40s or lower 50s on Tuesday.
"Wednesday is a toss up at this point" wrote the National Weather Service in Amarillo, Texas, expressing uncertainty as to exactly where the nudge of cold air ends up.
Farther east, Minneapolis is bracing for a downright frigid start to the workweek. Highs in the single digits are possible Tuesday and Wednesday. Lows in some of the outlying areas may drop to minus-10 or minus-15 Wednesday morning.
For the Great Lakes, the cold front arrives later Monday into Tuesday. After a cloudy and rainy day Monday with highs in the lower to middle 40s, Chicago will fall into the lower 20s for highs on Tuesday. A high temperature of just 18 is forecast for the Windy City on Wednesday, with lows in the single digits. Arctic high pressure will park overhead.
In Detroit, relatively temperate conditions stick around for one more day on Tuesday. Highs will be near 40. Cold air will rush in with gusty winds Tuesday night; highs will stick only to the mid-20s on Wednesday.
In Indianapolis and Columbus, the core of the cold arrives Wednesday. Highs in the 20s are likely, with lows potentially in the teens.
Predicting just how far south the cold will make it is a tricky game. When the cold splashes south, its leading edge can be very finicky. It's sort of like cruising down the highway, abruptly slamming your brakes on, and trying to guess beforehand which little white dash you're going to end up stopped next to.
New Orleans is predicted to hit only 58 degrees Wednesday, while Atlanta will hover about 50.
Some marginal severe weather risk may materialize over the immediate Gulf Coast during the Monday and Tuesday time frame as the cold front passes.
Unseasonable warmth will precede the blast of cold. A sprawling area of low pressure will scoot east over the Great Lakes into southern Ontario and Quebec early next week. Warm air will surge north ahead of it, before encroaching cold air from the north gets a helpful tug toward the Appalachians in its wake. The warm weather will spread over the Mississippi and Ohio Valleys Monday before becoming confined to the Eastern Seaboard on Tuesday.
Highs could approach 15 degrees above normal in spots, likely topping 60 in Washington, D.C., reaching into the upper 50s in Boston, and perhaps climbing to near 65 in Raleigh, North Carolina. The weather will be unsettled on Monday and Tuesday though, with intermittent showers and gray skies as the cold front draws near.
But then temperatures will fall sharply, around 20 degrees between Tuesday and Wednesday. Washington, D.C., may top 60 degrees Tuesday, then hover in the lower 40s Wednesday.
Models disagree on the specifics of the weather pattern after around Thursday. The American (GFS) model predicts reinforcing shots of Arctic air in the northern Plains and Great Lakes whereas the European model predicts the cold will retreat with normal to above normal temperatures covering much of the nation for the weekend of Dec. 14 and 15.
This article was written by Matthew Cappucci and Jason Samenow, reporters for The Washington Post.