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Insider Insights: Articles

Reporter's Notebook: Arctic Outflow

By Chris St. Clair
Weather Broadcaster
Wednesday, February 5, 2014, 9:18 AM

FOLLOW US IN B.C.: Chris St. Clair will be in British Columbia all week. Tune in for TV dispatches, and check back year for more of his insights. 

An Arctic Outflow is a weather phenomenon that occurs when High Pressure from the Arctic sags southward and situates itself over the Peace river region. The clockwise circulation of this air mass funnels dry cold air from the far north into the valleys of British Columbia. 

Cold air is dense, so it sinks rather rapidly to the surface. When combined with the topography of British Columbia an outflow pattern develops. Simply, rivers of very cold air rush through the valleys, westward towards the Pacific. 

You cold feel the cold winds rushing westward today at the Cypress Mountain Olympic venue. It made your eyes tear and nose run. Even at an elevation just 1500 metres above Vancouver, it was 7 degrees colder - and it was a cold day in Vancouver! 

Here on the coast, extra shelters have been opened for the homeless and less fortunate. The coldest days so far this winter will occur from now until Friday.  

Over Howe Sound this afternoon we watched whitecaps on the water illustrate the rush of cold air from the east. Given ideal circumstances, that plume of dry cold air will draw up moisture from the strait as it rushes westward toward Vancouver Island. When this stream of air meets the mountains it will rise higher into the atmosphere and cool even further, producing sea effect snow on the east side of the island.

More from Vancouver Island next time, plus the story of how much snow you can make on one cold day if you have the right equipment!

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