An intense cold spell has seized an intense and prolonged cold spell, with temperatures hovering in the minus 20 to minus 40 Celsius range for multiple weeks. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, marking its chilliest December reading in nearly five decades.
Prolonged Freeze Below -40C
Similarly, the communities of Mayo and Dawson experienced sixteen nights in a row below -40C, with Mayo plunging to -50.4C at the start of the week. The capital, Whitehorse, likewise saw 10 nights when temperatures dropped below -30C.
The bitter chill extended its reach south during the holiday season. In Edmonton, the Christmas overnight low dipped under -28 degrees Celsius.
The day after Christmas was forecast to deliver minimum temperatures of at least minus 20C across many regions, from Edmonton in the west to Quebec in the east.
Forecast to Persist For Days to Come
The severe cold is forecast to persist for the foreseeable future. Authorities have cautioned about potential power failures in the Yukon soon, as the territory’s power grid comes under strain from record-high energy demand.
The prolonged chill has been caused by the Arctic vortex settling above Canadian territory through December, allowing bitter Arctic air to spill south. Next week, the cold air mass is expected to retreat north gradually, enabling milder Pacific air to move across America and reach into portions of southern Canada.
Pronounced Disparity to American Heat
In stark contrast, parts of the US experienced their warmest Christmas Day on record 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.
A number of states broke historical records for December 25th warmth. The capital of Oklahoma soared to 25C on Christmas Day, topping the prior high mark of 22 degrees established over forty years ago. Cities including Austin and Dallas, in Texas, and Charlotte, North Carolina were also among those that recorded temperatures above 25C.
Atmospheric Ridge Drives the Heat
Warmer-than-normal conditions are forecast to last through Boxing Day and the days ahead, with unseasonable heat forecast to sweep through the American Southeast soon.
This heat is being driven by a strong upper-level ridge extending from the desert south-west towards the north and east, which generates a heat-dome phenomenon. This pattern establishes a broad area of high pressure over a large portion of North America, trapping warm air near the surface. As air sinks through the atmosphere, it compresses and heats further, enabling abnormally high temperatures to develop.
