Black ice is a thin layer that forms on surfaces such as roads, sidewalks and driveways when temperatures are 30 degrees or lower.

Texans in northern portions of the state are in the midst of a powerful winter storm Thursday, and road conditions near major metropoles are already getting dicey. Video of a highway near Dallas shows cars making their way gingerly through the storm,

North Texas is experiencing light slow, freezing drizzle and slick road conditions, causing road closures and traffic delays across the Metroplex.A winter storm advisory is in effect for certain areas until 12 p.