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The Yukon has been grappling with an extreme cold weather system that’s pushing the power grid to the brink because it can’t keep up with demand.

Communities like Faro, about 360 kilometres northeast of Whitehorse, and Carmacks, around 180 kilometres north of the territory’s capital, have been experiencing lows of –50 C since Monday.

Temperatures started to dip below –30 C earlier this month, and there’s been no relief since. Here’s what’s causing this inclement weather to stick around in the Yukon.

What’s behind these extreme temperatures?

“What we’re seeing in Yukon is an Arctic ridge of high pressure,” Environment Canada meteorologist Tanmay Rane told CBC News. “What happens is, once a cold front passes, all the cold air behind it follows the cold front.”

Since cold air tends to sink because it’s heavier than warm air, it sinks down to the surface, pushing the air surrounding it out of the way. 

“When it does that, when [cold air] clears the air underneath it, air from aloft comes down to fill that pocket,” Rane said. 

Air that’s aloft, or higher above the surface, is colder than the air that’s at the surface, so as it fills the pocket left behind, it creates cooler conditions, Rane said.

Alongside that sinking effect, skies have remained clear. Without clouds in the sky to absorb heat radiated from the Earth’s surface and send it back down, Rane said the heat escapes to space overnight, preventing temperatures from rising.

“So night after night, Yukon is getting colder and colder because of the clear skies, and a high-pressure system like that is pretty stagnant.”

How low have temperatures gotten?

Environment Canada issued yellow weather alerts to 11 Yukon communities, including Whitehorse. Here’s how low temperatures have gotten within the past 24 hours:

• Whitehorse: –44 C
• Pelly Ranch (Fort Selkirk): –48 C
• Faro: –50 C
• Dawson: –45 C
• Carmacks: –49 C

Environment Canada’s weather alert issued for Whitehorse has advised that extreme wind chill values can make temperatures feel as low as –50 C, but some moderation of temperatures are expected going into Christmas Day.

What effect does wind chill have on the cold?

Windier conditions tend to make you feel colder, according to Environment Canada. Wind chill values are different from recorded temperatures, because they can’t be measured by a thermometer. Rather, they’re measured by how cold your skin would feel in the wind. 

Wind chill values can tell you how cold you’ll feel outside, which can be different from the recorded temperature. 

It’s included in weather forecasting when wind speed is expected to be 5 km/h or more and when recorded temperatures are zero or below. 

Being exposed wind chill values between –48 C to –54 C comes with a severe risk of frostbite. According to Environment Canada, any exposed skin could freeze in less than five minutes and sometimes faster if winds stay consistently above 50 km/h.

How long could it last?

Although the cold isn’t going anywhere anytime soon, Rane said temperatures could gradually start to rise by next week.

“I don’t think it would get any colder,” Rane said. “This Arctic high that’s sitting over Yukon right now will slowly sink down into northern BC and then make its way out.” 

Once that happens, Rane said he expects that clouds will start coming in, leading to a slow increase in temperature.

Why could there be blackouts?

Yukon’s power grid is nearing capacity as electricity usage surged due to the cold. Demand reached a peak on Monday with 123 megawatts of power being pulled from a system that can accommodate 140 megawatts. 

Ted Laking, the minister responsible for Yukon Energy, said Tuesday that rolling blackouts may be enacted to alleviate the demand, though he added that Whitehorse hasn’t reached that stage yet. 

If rolling blackouts were to occur, they would happen by neighbourhood. To prepare, Laking has urged Yukon residents to compile emergency kits that would last 72 hours with supplies like flashlights, emergency blankets and food.