Brutally cold” air is expected to settle in behind the storm that will affect a dozen states, from eastern Colorado to Maryland.

A mixture of freezing rain, sleet, and snow have been seen across the St. Louis region on Sunday. FOX 2 extreme weather specialist Chris Higgins explains the difference between freezing rain and sleet and the danger they bring to roadways.

A major winter storm began Saturday in the central U.S. and was forecast to move east over the next several days, producing heavy snow, significant ice and frigid temperatures, according to the National Weather Service.