A winter storm that brought snow, sleet and freezing rain to a large swath of the Midwest swept into the mid-Atlantic and Northeast on Thursday, causing treacherous travel conditions, prompting school delays and closures and potential power outages for millions of Americans.

Freezing rain could lead to hazardous travel conditions across the entire Chicago area, especially during "peak timing" of the winter weather system.

Starting with an ice and snow storm Thursday, a series of winter systems is forecast to slam parts of the Midwest, Northeast and Mid-Atlantic with dangerous travel conditions through the middle of next week,