This upper-level temperature animation shows a deep trough plunging Arctic air south from Canada, allowing the polar vortex to funnel the coldest air of the season into the eastern United States.

Michigan is set for several days of frigid temperatures and heavy lake-effect snow as Arctic air continues its slow march across the eastern U.S. When Arctic air surges into the U.S., the polar vortex ...

Michigan is set for several days of frigid temperatures and heavy lake-effect snow as Arctic air continues its slow march ...