• SIOUX FALLS, S.D. (AP) -- It has been decades since parts of the Midwest experienced a deep freeze like the one expected to arrive Sunday, with potential record-low temperatures heightening fears of frostbite and hypothermia even in a region where residents are accustomed to bundling up.
• This "polar vortex," as one meteorologist calls it, is caused by a counterclockwise-rotating pool of cold, dense air. The frigid air, piled up at the North Pole, will be pushed down to the U.S., funneling it as far south as the Gulf Coast.
• Ryan Maue, of Tallahassee, Fla., a meteorologist for Weather Bell, said temperature records will likely be broken during the short yet forceful deep freeze that will begin in many places on Sunday and extend into early next week. That's thanks to a perfect combination of the jet stream, cold surface temperatures and the polar vortex.
• "All the ingredients are there for a near-record or historic cold outbreak," he said "If you're under 40 (years old), you've not seen this stuff before."
• The temperature predictions are startling: 25 below zero in Fargo, N.D., minus 31 in International Falls, Minn., and 15 below in Indianapolis and Chicago. At those temperatures, exposed skin can get frostbitten in minutes and hypothermia can quickly set in because wind chills could hit 50, 60 or even 70 below zero.
• Sunday's playoff game in Green Bay could be among one of the coldest NFL games ever played. Temperatures at Lambeau Field are expected to be a frigid minus 2 degrees when the Packers and San Francisco 49ers kickoff, and by the fourth quarter it'll be a bone-chilling minus 7, with wind chills approaching minus 30, according to the National Weather Service. Officials are warning fans to take extra safety measures to stay warm including dressing in layers and sipping warm drinks.
• Minnesota called off school for Monday statewide, the first such closing in 17 years, because of projected highs in the minus teens and lows as cold as 30 below. Milwaukee and Madison, Wis., students also won't be in class Monday. North Dakota Gov. Jack Dalrymple urged superintendents to keep children's safety in making

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