(NBC News) A blast of winter weather pushing down from Canada is bringing the coldest air of the season to much of the country.
The enormous, brutal mass of arctic air is shoving south over most of the united states, threatening 32 million people for the rest of the week with snow, ice, wind and extraordinary drops in the temperature.
Some of the country's biggest cities are being hit.
Ice threatens to knock out power in Dallas; Denver could get almost a foot of snow, and Chicago could plunge from the mid-50s on Wednesday to the low teens by Friday night.
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