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John Wheeler, WDAY, Published January 08 2014

Weather Talk: Polar vortex usual cause of long-term cold wave

The term “polar vortex” has been tossed around by the National Media all week like it is some new thing. It is not.

Actually, when our weather turns very cold like it has the past few weeks, it is usually because of the polar vortex. Although it has an impressive name, the polar vortex is a semipermanent low-pressure area thousands of feet in the air at the jet stream level of the atmosphere over the polar regions.

Occasionally, the jet stream pattern causes a piece of this circulation to drop southward, causing arctic air southward into the mid-latitudes. Ironically, as the polar air goes south, warmer air moves poleward, resulting in the situation in which the weather here in North Dakota is temporarily colder than it is at the North Pole.

Although it does not happen every winter, this situation is not at all unusual. It happens virtually every time our region has a long-term cold wave in the winter.

Have a weather question you’d like answered? Email weather@wday.com,

or write to WDAY Stormtracker, WDAY-TV, Box 2466, Fargo, ND 58108

Read the blog at a href="http://stormtrack.areavoices.com/">http://stormtrack.areavoices.com/.