Strength: The polar vortex strengthens in winter due to the deeper contrast between polar and equatorial temperatures and weakens in summer as temperature differences diminish. Normal Position ...

A developing area of upper-level arctic cold air will swing into much of the northern and eastern United States from Canada and will promote dangerously cold temperatures for central Kentucky and ...

A polar vortex is currently hitting the United States, with schools closed in many areas and at least four deaths caused by treacherous conditions.

Recent forecasts suggest some Americans might be getting a much-needed break from the freezing temperatures that have gripped much of the country.

The polar vortex of ultra-cold air usually spins around ... That could create treacherous road conditions. A Kentucky truck stop was jammed Monday with big rigs that had been forced off of snow ...

The University of Wisconsin-Madison faced a frigid start to the semester, with the polar vortex expected to bring more icy ...

Some 60 million people are under weather alerts across 30 states. Seven of them have declared emergencies: Maryland, Virginia, West Virginia, Kansas, Missouri, Kentucky and Arkansas ...

Elsewhere, a displaced lobe of the polar vortex has brought an unrelenting chill to large parts of the contiguous United States. About 30 states have experienced temperatures well below average ...

The polar vortex of ultra-cold air usually spins around ... More than 50,000 customers were without power on Wednesday in Indiana, Kentucky, Louisiana, Virginia and West Virginia, according ...

The polar vortex of ultra-cold air usually spins around ... More than 50,000 customers were without power on Wednesday in Indiana, Kentucky, Louisiana, Virginia and West Virginia, according ...

The polar vortex of ultra-cold air usually spins around ... according to forecasters. A Kentucky truck stop was jammed Monday with big rigs that had been forced off of snow-covered Interstate ...