Prolonged Chill Tightens Hold on the Great White North as US Records Most Unseasonably Mild Christmas in History.
Northern Canada has been gripped by a bitter and extended period of frigid weather, with readings persisting between -20C and -40C for an extended duration. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, marking its chilliest December reading in half a century.
Enduring Chill Below -40C
Meanwhile, Mayo and Dawson endured over two straight weeks of nights below -40C, with Mayo plunging to -50.4C on Monday. Whitehorse similarly reported ten separate nights when temperatures dropped below -30C.
This Arctic air mass pushed further southward over the festive period. On Christmas Day, overnight temperatures in Edmonton fell below -28C.
Boxing Day was expected to bring lows of at least -20C through a wide swath, including Edmonton, Montreal, Ottawa and Quebec.
Forecast to Persist into the New Year
The severe cold is forecast to persist through the start of January. Authorities have cautioned about potential power failures in the Yukon soon, as its energy infrastructure faces unprecedented demand from historically high electricity consumption.
The lengthy cold snap originates from the polar vortex remaining anchored above Canadian territory through December, enabling a surge of icy Arctic winds to descend. The frigid dome is projected to gradually withdraw north slowly, permitting warmer Pacific winds to flow over America and reach into portions of southern Canada.
Pronounced Disparity to American Heat
In stark contrast, parts of the US experienced historically high temperatures for Christmas as the mercury climbed roughly 15 to 30 degrees above typical averages. Across wide regions, the atmosphere was more akin to late spring instead of the heart of winter.
Several states set Christmas Day temperature records. The capital of Oklahoma soared to 25C on Christmas Day, topping the prior high mark of 22 degrees established over forty years ago. Urban centers like Austin, Dallas, and Charlotte, North Carolina were also among those that recorded temperatures above 25C.
High-Pressure System Fuels Warmth
Unseasonable heat is predicted to persist through Boxing Day and the days ahead, with atypical high temperatures expected to spread through the American Southeast soon.
The unseasonable temperatures are powered by a strong upper-level ridge extending from the desert south-west towards the north and east, establishing a classic heat-dome pattern. This setup creates an extensive zone of high atmospheric pressure over a large portion of North America, effectively capping warm air at lower altitudes. As air sinks through the atmosphere, it compresses and heats further, enabling abnormally high temperatures to develop.
