Polar vortex splitting brings uncertainty to Canada’s winter outlook

Résumé détaillé

Typically at this time of year the polar vortex would be strengthening. But the early split could bring a flush of early-winter cold air to parts of Canada.

With a record-breaking El Niño and the earliest recorded splitting of the polar vortex duking it out, Canada could have a very unpredictable winter.

The split in the polar vortex, which occurs when the winds change directions in the stratosphere above the North Pole, was officially recorded on Nov. 10, two weeks earlier than ever before.

Typically at this time of year the polar vortex would be strengthening, building up cold air for later in the season. But the early split could bring a flush of early-winter cold air to parts of Canada.

Global News meteorologist Anthony Farnell said an early split in the polar vortex is particularly mind boggling considering we are currently experiencing the strongest El Niño on record.

Water surface temperature in the Pacific hit at least 0.5 C above average in El Niño years but this year, the temperature has hit 3.5 C above average.

“I guess the big question is, are these two separate occurrences, these two records happening all at once, or is there some sort of a correlation? And then as a meteorologist, what does that mean?” Farnell said.

Much of Canada typically experiences a milder winter in El Niño years, but Farnell said the disruption of the polar vortex could favour some very cold air for much of December.

If the cold air does come sweeping across Canada, he said it will take a few weeks.

“Some of our computer models are now starting to bring in some snow and some colder air at the end of November and early December so I think there’s going to be a lot of back and forth coming,” he said.

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