Storms spawned at least one tornado, sent creeks over their banks and caused flash flooding Thursday in portions of West Virginia and Kentucky, while a wintry mix coated trees and roads in ice and even dropped “thunder ice” in several states.

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.