An intense cold spell has seized an intense and prolonged cold spell, with readings persisting from 20 to 40 degrees below zero for weeks. This week, the Yukon community of Braeburn saw the mercury drop to -55.7C, its coldest December temperature in half a century.
Enduring Chill of Extreme Cold
Meanwhile, Mayo and Dawson endured sixteen nights in a row colder than minus 40 degrees, with the temperature in Mayo bottoming out at -50.4 degrees Celsius at the start of the week. Whitehorse also recorded a series of ten nights when temperatures dropped below -30C.
The bitter chill extended its reach south through Christmas week. On Christmas Day, overnight temperatures in Edmonton fell below -28C.
Boxing Day was expected to bring readings no higher than -20 Celsius across many regions, including Edmonton, Montreal, Ottawa and Quebec.
Likely to Linger For Days to Come
This harsh winter weather is expected to continue into the new year. Officials have warned that the Yukon could face electricity outages over the next several days, as the system endures record-high pressure from historically high electricity consumption.
The prolonged chill has been caused by a stationary polar vortex above Canadian territory through December, which funnels frigid northern air southward. The frigid dome is projected to gradually withdraw north gradually, enabling milder Pacific air to move across the US and into parts of southern Canada.
Dramatic Difference with US Warmth
In stark contrast, parts of the US experienced the hottest December 25th in their history as temperatures soared about 15-30C above the seasonal average. In many areas, conditions felt more typical of April or May than late December.
Several states set Christmas Day temperature records. Oklahoma City, Oklahoma, reached 25 degrees Celsius on Christmas, 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.
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 across the southeastern US in the coming days.
The unseasonable temperatures are powered by a robust atmospheric 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 blanketing a significant part of the landmass, 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.
