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.

More than 30 million people are under winter weather alerts across the Midwest and Northeast early this week with another storm threatening to upend travelers’ plans on what is expected to be one of the busiest travel days this holiday season.

As the Northeast recovers from a heavy snowstorm, a new system is already moving through the Rockies and is expected to sweep across the country.

A powerful winter storm is impacting parts of the U.S. with major snowfall, ice, and below zero wind chills. The conditions are disrupting holiday travel and could last through next week.

Officials urge residents to monitor local forecasts as the winter storm system may continue to impact additional regions.