The weather outside is frightful thanks to climate change and the polar vortex

The weather outside is frightful thanks to climate change and the polar vortex
http://www.cbc.ca/news/canada/weather-winter-holiday-outlook-1.3885241?utm_content=buffera58ac&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

Climate change may, in fact, be to blame for this oh-so-Canadian winter.  

"Doesn't global warming mean that we're going to get warmer, shorter winters? Well, in some areas, yes, but it actually could mean we could see colder episodes," Environment Canada senior climatologist David Phillips told CBC News.

It's all part of a bigger puzzle that has to do with melting Arctic ice, extreme ocean temperatures, a travelling polar vortex and a weird, roller-coaster-shaped jet stream.

Goodbye El Nino, hello La Nina

The Weather Network's seasonal outlook says 2016 marks "a return to the classic Canadian winter" after last year's exceptionally warm one.
That's because last year's winter was tempered by El Nino, a period of uncharacteristically warm ocean temperatures in the equatorial Pacific.  This year, however, we get the opposite: La Nina.

That means near or below seasonal temperatures in every province and an active winter storm season — the beginning of which we're already seeing, even though winter doesn't officially kick off until Dec. 21.
Expect plenty of snow in the West Coast, the Prairies and central Canada, with a mix of snow, rain and ice in Atlantic Canada, and storms for everyone.
Only northern Canada — places like Labrador and the territories — can potentially expect lower-than-average temperatures.

Jet stream 'dips and dives'

Much of the winter will be punctuated by bitterly cold Arctic winds, travelling to us on the jet stream, a strong air current that flows several kilometers above the Earth.

"The jet stream is really the boundary between the warm air in the south and the cold air in the north," says Phillips. "What happens is the weather systems, they hook a ride on the jet stream. The jet stream is our weather-delivery system."

Usually, it moves from west to east across the country in a fairly predictable fashion. But in recent years the jet stream has undergone a transformation, Phillips says.