Deep Freeze Envelops the Great White North as America Sees Warmest Christmas in History.
A prolonged deep freeze has enveloped a severe and lengthy Arctic outbreak, with thermometers lingering from 20 to 40 degrees below zero for weeks. On Tuesday, Braeburn in the Yukon recorded -55.7C, its coldest December temperature in half a century.
Enduring Chill Below -40C
Similarly, the communities of Mayo and Dawson experienced over two straight weeks of nights below -40C, with Mayo experiencing a low of -50.4C at the start of the week. Whitehorse also recorded 10 nights when the cold dipped under -30 Celsius.
The bitter chill extended its reach south over the festive period. On Christmas Day, overnight temperatures in Edmonton fell below -28C.
The day after Christmas was forecast to deliver lows of at least -20C across many regions, including Edmonton, Montreal, Ottawa and Quebec.
Forecast to Persist into the New Year
The severe cold is forecast to persist for the foreseeable future. Authorities have cautioned about potential power failures in the Yukon soon, as the system endures record-high pressure from record-high energy demand.
The prolonged chill has been caused by the Arctic vortex settling over Canada for much of December, allowing bitter Arctic air to spill south. Next week, the cold air mass is expected to retreat north allowing more temperate air from the Pacific to sweep across the US and into parts of southern Canada.
Stark Contrast with US Warmth
In stark contrast, parts of the US experienced the hottest December 25th in their history 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, surpassing the previous peak of 22C set in 1982. Urban centers like Austin, Dallas, and Charlotte, North Carolina were also among those that recorded temperatures above 25C.
Heat-Dome Effect Sustains High Temperatures
Warmer-than-normal conditions are forecast to last through Boxing Day and the days ahead, with abnormal warmth projected to move through the American Southeast soon.
The unseasonable temperatures are powered by a powerful high-altitude ridge extending from the desert south-west towards the north and east, which generates a heat-dome phenomenon. Such a configuration results in a widespread high-pressure system over a large portion of North America, which holds warm air close to the ground. As air sinks through the atmosphere, it compresses and heats further, fostering the buildup of exceptional warmth.
