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September 19, 2017

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A blanket of fog covers Lake Michigan along the Chicago shoreline Monday, Jan. 6, 2014 as temperatures dove well below zero and wind chills were expected to reach 40 to 50 below.  A whirlpool of frigid, dense air known as a "polar vortex" descended Monday into much of the U.S.

Teresa Crawford / AP

A blanket of fog covers Lake Michigan along the Chicago shoreline Monday, Jan. 6, 2014 as temperatures dove well below zero and wind chills were expected to reach 40 to 50 below. A whirlpool of frigid, dense air known as a "polar vortex" descended Monday into much of the U.S.