'Polar vortex' to blame for U.S. freeze

Residents braves 15 degrees in Manhattan on January 3, 2014.
Residents braves 15 degrees in Manhattan on January 3, 2014.

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    'Polar vortex' to blame for U.S. freeze

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CNN meteorologist Chad Myers explains how a "polar vortex" is causing record low temperatures in the U.S.