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The Polar Vortex: Filtering The Science Through The Hype

January 9, 2014

By WeatherBug Sr. Meteorologists, John Bateman and James West

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Sorry to break it to you, but the "Polar Vortex", the new weather buzzwords that have been sweeping social media, isn't a newly discovered weather phenomenon at all, or even rare. It does, however, get people talking, and watching, and clicking their mouse to get more information on the "Weather Disaster Du Jour."

What it is, is a well-understood, ever-present, large-scale weather pattern that occasionally brings very cold air down into the contiguous 48. Disappointed yet? Well, we`ll at least try to make it more interesting from this point on.

The polar vortex, also known as a polar low or cyclone, was first theorized back in the mid-1800s after scientists began really studying these persistent areas of very cold air circulating both the North and South Poles. Over the years, it is has been discovered that these vortices are generally weakest in the summer and strongest in the winter and winter's strong circulation tends to keep it bottled up well north of the U.S. border.

Every so often this circulation can weaken a bit, and if that happens to coincide with an active jet stream pattern, pools of frigid air can be pulled southward. The Polar Vortex and the dipping jet stream delivers the polar cold air, it doesn`t create the cold air that builds over the polar region every year. This is what happened this week when temperatures plummeted across the U.S., and it has happened many times in the past.

The Cold Wave of January 1994 killed more than 100 people in the U.S., with Pittsburgh bottoming out at its record -22 degrees. Shelbyville, Ky., dropped to -37 degrees to shatter a state record which still stands. Chicago was hit particularly hard, with a low of -24 degrees, closed schools, cancelled flights, and widespread power outages lead to no heat.

Nine years earlier the worst arctic blast in modern history was the Arctic Outbreak of January 1985, when at least 126 people died from the cold snap, and some 90 percent of Florida`s citrus crop was destroyed. Nashville, Tenn., dropped to -17 on January 21, 1985, with Atlanta hitting -8. Gainesville, Florida even sank to 10 degrees and Miami bottomed out at 30 degrees on the 22nd.

Less than 100 years earlier, the worst recorded cold snap in U.S. history slammed the central and eastern U.S., in February 1899. Records that still stand today are -16 degrees in Minden, La. (still an all-time state record), -15 degrees in Washington, D.C., -8 in Dallas, and -2 in Tallahassee (still the only subzero temperature reading ever observed in Florida).

This week`s big arctic blast and the "Polar Vortex" is nothing new.

American Meteorological Society`s President, Dr. J. Marshall Shepherd, in a blog earlier this week said: "In the end, a term is not new just because you are not familiar with it. Most meteorologists and atmospheric scientists have known about the Polar Vortex for some time. We also knew what El Nino was before the 1998 El Nino. Derecho was a term before Washington D.C. experienced one."

This week`s event did freeze a lot of the U.S., making for some good post-holiday water-cooler and social web banter. Remember, it will happen again, guaranteed.

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Story Image: In this Sunday, Jan. 5, 2014, file photo, a person struggles to cross a street in blowing and falling snow as the Gateway Arch appears in the distance, in St. Louis. (Jeff Roberson, AP File)

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