The NWS says that, during winter in the Northern Hemisphere, the polar vortex often expands, carrying cold air southward ...

South of the Arctic’s polar vortex is the jet stream, a river of west to east air that flows five to nine miles above ground, and helps keep the pole’s cold air confined to the Arctic.

This week, the heart of Canada’s polar region will be milder than cities like Toronto, Hamilton, Ottawa, and Sault Ste. Marie, Ont.

Maps show where and when the cold front will arrive. The polar vortex is a large area ... During the winter months and when ...

If the upcoming vortex disruption weakens the jet stream, it may release cold air from polar regions into North America or Eurasia. “We are predicting a displacement of the polar vortex on the ...