Deep freeze grips U.S.

Frigid weather descended on much of the United States on Wednesday, thanks to a split in the polar vortex. Officials from Montana to Maine and as far south as Georgia urged residents to take precautions amid the freezing cold. The Midwest bore the brunt of the freeze, with the temperature hitting minus 20 degrees in Chicago by Wednesday morning, breaking the previous record low for the day set in 1966. The U.S. Postal Service suspended mail delivery on Wednesday in parts or all of Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Nebraska, North Dakota, South Dakota, and Wisconsin.

“These [conditions] are actually a public health risk and you need to treat it appropriately,” Chicago Mayor Rahm Emanuel said Tuesday. “They are life-threatening conditions and temperatures.” Many schools shut down as far south as Atlanta, where a predicted winter storm never materialized. But like much of the country, the city was not spared a hard freeze.

The frigid weather resulted when a rush of warm air from the South split the polar vortex—the cold air that normally swirls above the North Pole—into pieces, causing a rise in temperatures in the Arctic and leaving sections of the vortex to wander south, bringing cold air with it.