Warmest fall on record for many Kivalliq communities set to break next week as winds shift

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The unusually warm weather hanging over the Kivalliq region of Nunavut is poised to end this weekend, but the lingering effects of the warmest fall on record for many communities have yet to be seen.

October brought record-setting heat to many parts of the Arctic, prompting some people in Arviat to swap their winter boots for rubber ones and don shorts to go skating. Temperatures stayed higher than average in November as well.

Arviat, Baker Lake, Rankin Inlet and Cambridge Bay all had their warmest falls on record, while Resolute Bay had its second warmest.

That's all set to end after this weekend, when Terri Lang, a meteorologist with Environment and Climate Change Canada, says cold air is set to move in.

"That will hopefully break that pattern and get the bay frozen up as well," Lang said.

Jason Ross, a senior ice forecaster with the Canadian Ice Service, says the Kivalliq region is on the verge of a temperature shift.

Some areas, such as Rankin Inlet, are now under a blizzard warning. High winds from the north should sweep through the region this weekend, cooling the waters of Hudson Bay and pushing coastal ice outward, allowing new ice to form along the coast. As winds calm next week, he said he expects a "rapid freeze event" to happen.

Low ice levels

Harry Towtongie, the mayor of Rankin Inlet, says low ice levels in the region mean hunters have had to change the way they access the land. Lakes, rivers and the bay would usually be frozen before November, but that still hasn't happened in some areas.

"They've had to take long routes up the inlet and along on the land," he said. "That's the most impact we've noticed — we can't just cross the lakes and rivers."

Ross told CBC News the warm weather means just 13 per cent of northwestern Hudson Bay was covered with ice by the end of November  — compared to 70 or 80 per cent in an average year.

He could find just three other years on record where ice levels were so low: in 2016, there was 19 per cent ice coverage; in 2011, it was 16 per cent; and 17 per cent in 1998.

"We've seen a trend throughout the ice climatology, since the mid-90s, that we have seen quite a bit of decline in the ice — it forms later in the year and in general it's thinner," he said.

"These periods of low ice are happening more and more often.

Farewell to La Niña?

It isn't clear yet how or if the aftershocks of record-breaking heat will impact the rest of the season.

Lang said it's possible that heat could throw off predictions of a La Niña winter — that is, colder than average temperatures with more precipitation.

"With the Arctic waters as warm as they are, that might not pan out," she noted.

Open water affects weather patterns as well, she said. With so much of Hudson Bay open, it could "muck up" weather patterns across the country.

"When there's a big puddle, or a big source of warmer-than-average air, it actually affects the way the jet stream moves," she explained. "There's a lot of water in Hudson Bay, so a lot of what we call latent heat."

Ross says it's hard to say if the warmth will affect spring breakup. A deep freeze later this winter could compensate for the earlier warmer weather — or, if that doesn't happen, the ice will be thinner throughout the season and could break earlier.

He noted December should bring a return to average temperatures, and perhaps slightly colder than normal temperatures along the northwest coast of Hudson Bay.

On Friday, Chesterfield Inlet, Clyde River, Gjoa Haven, Naujaat, Taloyoak and the Rankin Inlet region including Whale Cove had weather warnings for winter storms.