Prolonged Chill Grips Canada as America Sees Most Unseasonably Mild Christmas on Record.
A prolonged deep freeze has enveloped a bitter and extended period of frigid weather, with thermometers lingering between -20C and -40C for weeks. On Tuesday, Braeburn in the Yukon recorded -55.7C, marking its chilliest December reading since 1975.
Prolonged Freeze in the Deep Minus Forties
In addition, the locales of Mayo and Dawson suffered through over two straight weeks of nights dipping under the minus 40 Celsius threshold, with the temperature in Mayo bottoming out at -50.4 degrees Celsius on Monday. Whitehorse also recorded 10 nights when temperatures dropped below -30C.
This Arctic air mass pushed further southward through Christmas week. Christmas night saw Edmonton's temperatures plummet below minus 28C.
The day after Christmas was forecast to deliver minimum temperatures of at least minus 20C through a wide swath, encompassing cities from Edmonton to Quebec.
Likely to Linger For Days to Come
The severe cold is forecast to persist through the start of January. Officials have warned that the Yukon could face electricity outages soon, as the territory’s power grid comes under strain 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. 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.
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. For numerous locations, the weather resembled a spring day in April or May than late December.
Multiple states established new Christmas temperature highs. The capital of Oklahoma soared to 25C on Christmas Day, 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 Fuels Warmth
Warmer-than-normal conditions are forecast to last 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 powerful high-altitude ridge extending from the desert south-west towards the north and east, establishing a classic heat-dome pattern. 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, enabling abnormally high temperatures to develop.
