Michigan is experiencing frigid temperatures and heavy snow due to a dip in the jet stream, not the polar vortex. The polar vortex is a large-scale cyclone of cold air that typically stays far north ...

When the polar vortex stumbles, the weather at ground level can pivot from mild to brutal in a matter of days. A circulation that usually spins quietly above the pole can suddenly send lobes of Arctic ...

Add Yahoo as a preferred source to see more of our stories on Google. Michigan is set for several days of frigid temperatures and heavy lake-effect snow as Arctic air continues its slow march across ...