Arctic Blast Tightens Hold on the Great White North as US Records Most Unseasonably Mild Christmas on Record.
An intense cold spell has seized a severe and lengthy Arctic outbreak, with thermometers lingering from 20 to 40 degrees below zero for weeks. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, representing its most frigid December day in half a century.
Consecutive Nights in the Deep Minus Forties
Meanwhile, Mayo and Dawson endured 16 consecutive nights below -40C, with Mayo experiencing a low of -50.4C at the start of the week. Whitehorse also recorded 10 nights when temperatures dropped below -30C.
The deep freeze spread farther south during the holiday season. Christmas night saw Edmonton's temperatures plummet below minus 28C.
Boxing Day was expected to bring minimum temperatures of at least minus 20C across many regions, including Edmonton, Montreal, Ottawa and Quebec.
Likely to Linger For Days to Come
The severe cold is forecast to persist through the start of January. Authorities have cautioned about potential power failures in the Yukon in the coming days, as its energy infrastructure faces unprecedented demand from historically high electricity consumption.
The lengthy cold snap originates from the Arctic vortex settling over Canada for much of December, allowing bitter Arctic air to spill south. In the coming week, forecasts indicate this cold air will pull back northward gradually, enabling milder Pacific air to move across America and reach into portions of southern Canada.
Pronounced Disparity to American Heat
Conversely, sections of America recorded historically high temperatures for Christmas as the mercury climbed roughly 15 to 30 degrees above typical averages. For numerous locations, the weather resembled a spring day in April or May instead of the heart of winter.
Multiple states established new Christmas temperature highs. In Oklahoma, Oklahoma City hit 25C on Tuesday, surpassing the previous peak of 22C set in 1982. Urban centers like Austin, Dallas, and Charlotte, North Carolina were also among those that recorded temperatures above 25C.
Heat-Dome Effect Drives the Heat
Above-average warmth is expected to continue for the remainder of the week and beyond, with unseasonable heat forecast to sweep through the American Southeast soon.
This heat is being driven by a powerful high-altitude ridge extending from the desert south-west towards the north and east, which generates a heat-dome phenomenon. This setup creates an extensive zone of high atmospheric pressure blanketing a significant part of the landmass, trapping warm air near the surface. Sinking atmospheric air undergoes compression and additional heating, fostering the buildup of exceptional warmth.
