A forecast map from the National Weather Service (NWS) shows which states can expect the coldest conditions, with a fresh arctic blast expected this weekend. “Another shot of arctic air is on the way ...

A fresh blast of Arctic air is poised to spill across a wide swath of the United States, and the latest polar vortex map makes clear which regions are most exposed. Forecast models show a sharp ...

The stratospheric polar vortex, the winter engine that traps Arctic cold high above the North Pole, is entering its seasonal collapse. What's left is the lower-level polar vortex core, lingering over ...

Michigan and the Great Lakes are bracing for another cold shot later this month — down to single digits in places — as a polar vortex split in the stratosphere nudges frigid Arctic air southward.