Of all the precipitation types, freezing rain is by most measures the worst because it can weigh heavily on trees and power lines.

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.

An active weather pattern is delivering back-to-back winter storms through the weekend. Here's what to expect.