How the Polar Vortex Will Impact Weather Across the United States This Winter

From December 1, 2013, to April 10, 2014, a powerful polar vortex caused temperatures to plummet 20 to 30 degrees below average throughout Canada and the United States. At least 21 people died in weather-related incidents during this North American cold wave.

Unfortunately, another polar vortex is forming over the North Pole and may strengthen rapidly as this winter approaches. There is growing concern that a repeat of the 2014 event may be on the horizon for much of the United States once again.

What Is a Polar Vortex?

A polar vortex is a large area of low-pressure and cold air that usually remains at Earth's poles. It lies in the stratosphere above the troposphere, which is where day-to-day weather occurs. While the polar vortex always exists, it usually strengthens and becomes more defined in the wintertime.

The coldest air within this vortex typically stays contained near the poles. However, sometimes it weakens. If the polar vortex weakens significantly or entirely collapses, this cold air will spill southward, impacting large portions of the United States, Canada and Europe.