An unusually early split in the polar vortex could send cold air into parts of Canada heading into December, complicating a winter outlook already shaped by a powerful El Niño, according to Global News meteorologist Anthony Farnell.

Global News reported that the split was officially recorded Nov. 10, two weeks earlier than any previously recorded occurrence. The disruption involves winds changing direction in the stratosphere above the North Pole, at a time when the vortex would normally be strengthening and building up cold air for later in the season.

The competing weather patterns leave considerable uncertainty about how Canada’s early winter will unfold. Much of the country typically experiences milder conditions during El Niño years, but Farnell said the disrupted vortex could favour very cold air through much of December.

Any cold air sweeping across Canada would take a few weeks to arrive, he said. Some forecast models are beginning to indicate snow and colder conditions toward the end of November and early December.

“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,” Farnell told Global News.

The report described the current El Niño as the strongest on record, with Pacific surface water temperatures reaching 3.5 C above average. It contrasted that with the threshold of at least 0.5 C above average associated with El Niño years.

Farnell questioned whether the two unusual developments were separate occurrences or connected, without offering a definitive answer.

Meteorologists expect the polar vortex could begin recovering within a week as stratospheric winds strengthen, Global News reported. Farnell compared that recovery to a spinning figure skater regaining balance after a disruption, while cautioning that another loss of balance remains possible.

Sources