A potent winter storm threatened blizzard-like conditions, treacherous travel and power outages in parts of the Upper Midwest as other areas of the country braced Monday for plunging temperatures, strong winds and a mix of snow, ice, and rain.

A potent winter storm threatened blizzard-like conditions, treacherous travel and power outages in parts of the Upper Midwest as other areas of the country braced Monday for plunging temperatures, strong winds and a mix of snow, ice, and rain.