Arctic Blast Tightens Hold on the Great White North as America Sees Most Unseasonably Mild Christmas on Record.
An intense cold spell has seized a severe and lengthy Arctic outbreak, with temperatures hovering between -20C and -40C for weeks. On Tuesday, Braeburn in the Yukon recorded -55.7C, representing its most frigid December day in half a century.
Enduring Chill Below -40C
In addition, the locales of Mayo and Dawson suffered through 16 consecutive nights dipping under the minus 40 Celsius threshold, with Mayo plunging to -50.4C earlier this week. Whitehorse similarly reported a series of ten nights when readings fell to minus 30 degrees or lower.
The deep freeze spread farther south during the holiday season. On Christmas Day, overnight temperatures in Edmonton fell below -28C.
The day after Christmas was forecast to deliver readings no higher than -20 Celsius across many regions, encompassing cities from Edmonton to Quebec.
Forecast to Persist Through Early January
This harsh winter weather is expected to continue for the foreseeable future. There are warnings of possible electrical grid strain in Yukon territory over the next several days, as the system endures record-high pressure from record-high energy demand.
The lengthy cold snap originates from the Arctic vortex settling over Canada for much of December, 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.
Stark Contrast Compared to Stateside Temperatures
Conversely, sections of America recorded the hottest December 25th in their history as temperatures soared about 15-30C above the seasonal average. Across wide regions, the atmosphere was more akin to late spring rather than the end of December.
Multiple states established new Christmas temperature highs. In Oklahoma, Oklahoma City hit 25C on Tuesday, exceeding the old record of 22C from 1982. Cities including Austin and Dallas, in Texas, and Charlotte, North Carolina also logged readings above 25 degrees Celsius.
Heat-Dome Effect Sustains High Temperatures
Warmer-than-normal conditions are forecast to last on December 26th and into the weekend, with unseasonable heat forecast to sweep into the south-eastern states later in the week.
The warmth has been fuelled by a robust atmospheric ridge stretching from the southwestern deserts northward and eastward, establishing a classic heat-dome pattern. This pattern establishes a broad area of high pressure across much of the continent, effectively capping warm air at lower altitudes. As air sinks through the atmosphere, it compresses and heats further, fostering the buildup of exceptional warmth.
