Prolonged Chill Tightens Hold on Canada as America Sees Warmest Christmas in History.
An intense cold spell has seized a bitter and extended period of frigid weather, with temperatures hovering in the minus 20 to minus 40 Celsius range for weeks. This week, the Yukon community of Braeburn saw the mercury drop to -55.7C, representing its most frigid December day in nearly five decades.
Enduring Chill in the Deep Minus Forties
Similarly, the communities of Mayo and Dawson experienced 16 consecutive nights below -40C, with the temperature in Mayo bottoming out at -50.4 degrees Celsius at the start of the week. Whitehorse similarly reported ten separate nights when temperatures dropped below -30C.
The bitter chill extended its reach south over the festive period. Christmas night saw Edmonton's temperatures plummet below minus 28C.
The day after Christmas was forecast to deliver readings no higher than -20 Celsius across many regions, including Edmonton, Montreal, Ottawa and Quebec.
Likely to Linger Through Early January
This harsh winter weather is expected to continue into the new year. Officials have warned that the Yukon could face electricity outages in the coming days, as the system endures record-high pressure from historically high electricity consumption.
The prolonged chill has been caused by a stationary polar vortex over Canada for much of December, which funnels frigid northern air southward. In the coming week, forecasts indicate this cold air will pull back northward gradually, enabling milder Pacific air to move across the US and into parts of southern Canada.
Pronounced Disparity with US Warmth
In stark contrast, parts of the US experienced historically high temperatures for Christmas as readings skyrocketed 15 to 30 degrees Celsius above normal. Across wide regions, the atmosphere was more akin to late spring instead of the heart of winter.
Several states set Christmas Day temperature records. Oklahoma City, Oklahoma, reached 25 degrees Celsius on Christmas, surpassing the previous peak of 22C set in 1982. Metropolitan areas such as Austin, Dallas, and Charlotte were also among those that recorded temperatures above 25C.
Atmospheric Ridge Drives the Heat
Warmer-than-normal conditions are forecast to last on December 26th and into the weekend, with unseasonable heat forecast to sweep 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, creating a heat-dome effect. This pattern establishes a broad area of high pressure blanketing a significant part of the landmass, which holds warm air close to the ground. Descending air compresses and adiabatically warms, allowing unusually warm temperatures to build.
