High above the North Pole, in a slice of atmosphere rarely noticed and even less understood, a transformation is underway. Over the next 10 days, changes in the stratosphere will upend weather ...

Frigid temperatures are expected to impact much of the central and eastern United States in the coming weeks. The first of three polar vortex systems is expected this month, according to AccuWeather.

January is shaping up to be the coldest in a decade as the polar vortex dips south across the eastern half of the United States — shocking a nation that has enjoyed an unusually balmy end of the year.