Deep Freeze Envelops Canada as United States Experiences Most Unseasonably Mild Christmas in History.
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 weeks. On Tuesday, Braeburn in the Yukon recorded -55.7C, marking its chilliest December reading in half a century.
Consecutive Nights of Extreme Cold
In addition, the locales of Mayo and Dawson suffered through 16 consecutive nights below -40C, with Mayo plunging to -50.4C at the start of the week. The capital, Whitehorse, likewise saw 10 nights when readings fell to minus 30 degrees or lower.
The bitter chill extended its reach south over the festive period. On Christmas Day, overnight temperatures in Edmonton fell below -28C.
Boxing Day was expected to bring minimum temperatures of at least minus 20C across many regions, including Edmonton, Montreal, Ottawa and Quebec.
Forecast to Persist into the New Year
This harsh winter weather is expected to continue into the new year. There are warnings of possible electrical grid strain in Yukon territory over the next several days, as the system endures record-high pressure from peak power usage levels.
This extended freeze is the result of the Arctic vortex settling above Canadian territory through December, which funnels frigid northern air southward. Next week, the cold air mass is expected to retreat north slowly, permitting warmer Pacific winds to flow over the United States and penetrate southern Canadian regions.
Dramatic Difference with US Warmth
Meanwhile, in a dramatic contrast, areas of the United States saw the hottest December 25th in their history as the mercury climbed roughly 15 to 30 degrees above typical averages. In many areas, conditions felt more typical of April or May than late December.
A number of states broke historical records for December 25th warmth. In Oklahoma, Oklahoma City hit 25C on Tuesday, topping the prior high mark of 22 degrees established over forty years ago. Metropolitan areas such as Austin, Dallas, and Charlotte were also among those that recorded temperatures above 25C.
High-Pressure System Fuels Warmth
Above-average warmth is expected to continue on December 26th and into the weekend, with abnormal warmth projected to move through the American Southeast soon.
The warmth has been fuelled by a strong upper-level ridge reaching from the arid southwest across the continent, establishing a classic heat-dome pattern. Such a configuration results in a widespread high-pressure system over a large portion of North America, trapping warm air near the surface. Descending air compresses and adiabatically warms, allowing unusually warm temperatures to build.
