El Niño winters are typically mild. What’s driving extreme cold in Canada?

globalnews.ca:

After the warmest December on record, an extreme cold wave is sweeping through Canada bringing heavy snowfall and strong winds that are forecast to continue this week.

Special weather statements and extreme cold or snowfall warnings were in place Monday in all the provinces and territories, according to Environment and Climate Change Canada.

Over the weekend, several cold temperature records were broken in Alberta, British Columbia, Saskatchewan and the Northwest Territories.

Global News meteorologist Ross Hull said “much of the country is experiencing the deep freeze” due to the cold Arctic air drifting south with the polar vortex descended.

The polar vortex is a large area of low pressure and cold air surrounding both of the Earth’s poles, according to the U.S. National Weather Service.

It’s not unusual for Canada to get episodes of polar vortices during winter, flooding down a burst of Arctic air from high latitudes that can result in a cold snap once or twice every winter, experts say.

But this current extreme cold wave, which is expected to continue in parts of the country this week, seems all the “more significant” when contrasted with how mild December was, said Geoff Coulson, a warning preparedness meteorologist with Environment Canada.

December was warmer than any previous year, European climate agency Copernicus said in its annual report released last week, confirming 2023 as the hottest year on record.

Coulson said the “mildness of December” in many parts of Canada makes this current cold outbreak “stand out.”

“What’s really noteworthy about this particular outbreak of Arctic air is just the amount of the country that’s being influenced by it in one way or another,” Coulson said in interview with Global News