Northern Canada has been gripped by a severe and lengthy Arctic outbreak, with readings persisting in the minus 20 to minus 40 Celsius range for weeks. On Tuesday, Braeburn in the Yukon recorded -55.7C, representing its most frigid December day since 1975.
Prolonged Freeze Below -40C
Similarly, the communities of Mayo and Dawson experienced over two straight weeks of nights dipping under the minus 40 Celsius threshold, with Mayo plunging to -50.4C earlier this week. Whitehorse also recorded a series of ten nights when readings fell to minus 30 degrees or lower.
This Arctic air mass pushed further southward during the holiday season. In Edmonton, the Christmas overnight low dipped under -28 degrees Celsius.
December 26th was anticipated to usher in lows of at least -20C across many regions, including Edmonton, Montreal, Ottawa and Quebec.
Forecast to Persist 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 soon, as the system endures record-high pressure from peak power usage levels.
This extended freeze is the result of a stationary polar vortex across the northern part of the continent this month, 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 United States and penetrate southern Canadian regions.
Dramatic Difference Compared to Stateside Temperatures
In stark contrast, parts of the US experienced historically high temperatures for Christmas as temperatures soared about 15-30C above the seasonal average. Across wide regions, the atmosphere was more akin to late spring than late December.
Several states set Christmas Day temperature records. Oklahoma City, Oklahoma, reached 25 degrees Celsius on Christmas, exceeding the old record of 22C from 1982. Cities including Austin and Dallas, in Texas, and Charlotte, North Carolina similarly saw thermometers rise past the 25C mark.
High-Pressure System Fuels Warmth
Unseasonable heat is predicted to persist on December 26th and into the weekend, with atypical high temperatures expected to spread into the south-eastern states later in the week.
The unseasonable temperatures are powered by a robust atmospheric ridge reaching from the arid southwest across the continent, creating a heat-dome effect. 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. Descending air compresses and adiabatically warms, fostering the buildup of exceptional warmth.
