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.

A winter storm covered the Northeast and Midwest regions of the United States with snow and ice on Feb. 5-6 prompting school closures across the regions. Sightings of lightning and thunder snow have also been reported.