Global warming changed the behavior of the jet stream, and a new pattern is now clear: sapping moisture from the West Coast and freezing the East.

A procession of winter storms is forecast to bring snow, sleet, ice and potentially flood-inducing rain to sprawling bands of the U.S. this week.

Two thousand miles east, in the heartland of America ... Then in January 2018, the eastern United States plunged into another deep freeze while the West remained stubbornly warm and dry.