Dramatic warm-up happening in the Arctic and Nunavut
Atmospheric warming event is going to flip those extreme cold warnings on their head
Every winter I, along with most meteorologists, watch something really carefully — the polar vortex. High up in the atmosphere, this vortex is an area of low pressure that could simply be described as a huge swirling pool of cold, frigid air.
When people hear the words, they think cold and snow, and for good reason. If the polar vortex is strong, it stays together, spinning above the North Pole, and the cold air stays over the Arctic. But sometimes it weakens and wobbles and swirls every which way. When it does that, pieces break off and big weather events of cold and snow hit the southern parts of Canada, the northeast United States and regions of northwestern Europe.
Big warming event this week
This week there are a few things happening with the polar vortex that are mixing things up in the North.
One of those is a sudden stratospheric warming event. During these types of events, the polar vortex weakens substantially and temperatures increase up to 50 C in the upper atmosphere.
This warming often leads to lighter winds — sometimes they even change direction — in the upper atmosphere and erratic behaviour of the vortex. Energy is also transferred through different layers of the atmosphere. This energy transfer can quickly change weather conditions and lead to some big weather events including mild temperatures and tremendous blizzards.
Because of the weakening, the polar vortex is basically splitting in two, and one of those pieces is quickly dissipating over the territories leading to warmer temperatures.
The polar vortex brought cold air
In the North, we are used to cold temperatures and the polar vortex sitting around.
I have talked about it every day because it has been sitting over the Kitikmeot. Combined with clear conditions, extreme cold warnings were in effect for the first week of January in communities like Sanirajak, Kugaaruk and Taloyoak for temperatures in the - 40 C range as the vortex spun above them.
Kugaaruk broke its Jan. 5 low temperature record of -42 C from 1985, with a new low record of -47 C, while Sanirajak recorded wind chills on Jan. 6 of -57 C.
But again, as the polar vortex weakens this week, things are changing.
Warm-up from retreating polar vortex
Through the day Wednesday and into Thursday, the polar vortex is rapidly retreating away from Nunavut. Here comes the wobble and weakening!
This, combined with an influx of warm Pacific air, means that temperatures are set to soar across the North, but particularly in Nunavut.
And when I say soar, I mean upwards of 25 C warmer in a matter of 48 hours.
Taloyoak, Kugaaruk and Sanirajak are all set to be -18 C on Jan. 7. This is 26 C warmer than the high on Jan. 5.
Above seasonal temperatures expected across most of the North
Cold air was also locked in over areas of the N.W.T. and Yukon through late December and early January.
As the polar vortex retreats, temperatures are set to be above seasonal for the next week or so. Most communities from Inuvik to Kugluktuk to Dawson are set to see a significant warm-up this week.