• The polar vortex is a large area of low pressure and cold air surrounding both of the Earth’s poles.
  • It ALWAYS exists near the poles, but weakens in summer and strengthens in winter.
  • The term “vortex” refers to the counter-clockwise flow of air that helps keep the colder air near the Poles.
  • Many times during winter in the northern hemisphere, the polar vortex will expand, sending cold air southward with the jet stream
  • This occurs fairly regularly during wintertime and is often associated with large outbreaks of Arctic air in the United States.
  • The one that occurred January 2014 is similar to many other cold outbreaks that have occurred in the past, including several notable colder outbreaks in 1977, 1982, 1985 and 1989.
  • There are several things the polar vortex is NOT. Polar vortexes are not something new.
  • The term “polar vortex” has only recently been popularized, bringing attention to a weather feature that has always been present.
  • It is also not a feature that exists at the Earth’s surface.
  • Weather forecasters examine the polar vortex by looking at conditions tens of thousands of feet up in the atmosphere; however, when we feel extremely cold air from the Arctic regions at Earth’s surface, it is sometimes associated with the polar vortex.
  • This is not confined to the United States. Portions of Europe and Asia also experience cold surges connected to the polar vortex.
  • By itself, the only danger to humans is the magnitude of how cold temperatures will get when the polar vortex expands, sending Arctic air southward into areas that are not typically that cold.

Tell us more about it

  • A polar vortex is an area of low pressure—a wide expanse of swirling cold air—that is parked in polar regions.
  • The one up north can cause some pretty wild weather and sub-zero temperatures in the United States.
  • But it’s not a new thing—this low-pressure system is almost always up there.
  • Sometimes this low-pressure system, full of cold Arctic air, strays a little bit too far from home. Part of it can break off and migrate southward, bringing all of that cold air with it.
  • Just like that, areas as far south as Florida get to experience their own little taste of life in the Arctic.
  • The breaking off of part of the vortex is what defines a polar vortex event. But it actually occurs when the vortex is weaker, not stronger.
  • That might sound weird—but it actually makes sense.
  • Normally, when the vortex is strong and healthy, it helps keep a current of air known as the jet stream traveling around the globe in a pretty circular path.
  • This current keeps the cold air up north and the warm air down south.
  • But without that strong low-pressure system, the jet stream doesn’t have much to keep it in line.
  • It becomes wavy and rambling.
  • Put a couple of areas of high-pressure systems in its way, and all of a sudden you have a river of cold air being pushed down south along with the rest of the polar vortex system.
  • That’s what happened in early 2014.
  • The polar vortex suddenly weakened, and a huge high-pressure system formed over Greenland.
  • The high-pressure system blocked the escape of all that cold air in the jet stream, and allowed part of the polar vortex to break off and move southward.
  • Places as far south as Tampa, Florida experienced the wrath of this wandering polar vortex. Most of Canada and parts of the Midwestern United States had temperatures colder than Alaska at the height of this cold snap!
  • It’s important to remember that not all cold weather is the result of the polar vortex.
  • While the polar vortex is always hanging out up north, it normally minds its own business.
  • It takes pretty unusual conditions for it to weaken or for it to migrate far south, and other things can cause cold arctic air to travel our way, too.