It's something very weird and nuanced going on right now,’ says one expert about the potential reasons for the snow blanketing much of the southern U.S.

A major winter storm slammed the southern US Tuesday, blanketing parts of the Gulf Coast with record-breaking snowfall in a region largely unaccustomed to extreme winter weather.

A historic winter storm swept across the Gulf Coast on Tuesday, bringing heavy snow and icy conditions to the Southeast while most of the country was facing dangerously cold temperatures from an arctic blast that arrived over the weekend.