22 June 2014 Polar Vortex and Winter Weather

Arctic's Influence on Weather

The winter of 2013 - 14 brought record breaking weather to the U.S.

Weather patterns, including this past winter's weather, circulate around the world because of the jet stream. The jet stream is a band of fast moving air about 10 km (6 miles) above Earth's surface. In the U.S., the jet stream generally blows from west to east. Pilots use the jet stream to their advantage. A flight between San Francisco and New York, flying with the jet stream, takes less time than the reverse trip, against the jet stream.

Location of the northern hemisphere jet stream is determined, in part, by the difference in temperatures between Arctic and tropical zones. As the polar regions warm, scientists are watching how this will effect weather patterns.

This past winter, an area of high pressure became stationed over the Arctic, pushing cold Arctic air deep into the U.S. This is known as a polar vortex. Much of the east coast had colder weather than usual, with some states being 30ºF below average temperature. Several areas had over 200% of typical snowfall.

An Arctic high pressure zone also stalled a wet weather system over the United Kingdom, bringing record rains to most of the U.K.

Follow the link below to a NASA animation of the jet stream movement over North America. The animation shows how far south the polar vortex extended. The red bands show areas of high moisture. Also notice how the jet stream is moving over the west coast. Storms stayed north, bringing rain to the Pacific northwest but leaving California and the southwest dry. California experienced its third year in a row of low rainfall and snowfall. Precipitation amounts were two-thirds the expected amount.

Whether you live on the east coast or west coast, you can blame your past winter weather on the Arctic!

Animated Jet Stream (http://www.weather.com/news/science/environment/how-wavy-jet-stream-splits-countrys-weather-apart-20140623