An intense cold spell has seized an intense and prolonged cold spell, with readings persisting between -20C and -40C for multiple weeks. This week, the Yukon community of Braeburn saw the mercury drop to -55.7C, its coldest December temperature in nearly five decades.
Consecutive Nights in the Deep Minus Forties
In addition, the locales of Mayo and Dawson suffered through sixteen nights in a row below -40C, with Mayo experiencing a low of -50.4C on Monday. Whitehorse also recorded ten separate nights when temperatures dropped below -30C.
The bitter chill extended its reach south over the festive period. In Edmonton, the Christmas overnight low dipped under -28 degrees Celsius.
The day after Christmas was forecast to deliver readings no higher than -20 Celsius across many regions, including Edmonton, Montreal, Ottawa and Quebec.
Forecast to Persist into the New Year
The severe cold is forecast to persist through the start of January. There are warnings of possible electrical grid strain in Yukon territory in the coming days, as the system endures record-high pressure from historically high electricity consumption.
This extended freeze is the result of a stationary polar vortex over Canada for much of December, enabling a surge of icy Arctic winds to descend. In the coming week, forecasts indicate this cold air will pull back northward allowing more temperate air from the Pacific to sweep across America and reach into portions of southern Canada.
Pronounced Disparity with US Warmth
In stark contrast, parts of the US experienced the hottest December 25th in their history 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 rather than the end of December.
Multiple states established new Christmas temperature highs. The capital of Oklahoma soared to 25C on Christmas Day, 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.
Atmospheric Ridge Drives the Heat
Above-average warmth is expected to continue on December 26th and into the weekend, with unseasonable heat forecast to sweep into the south-eastern states later in the week.
The unseasonable temperatures are powered 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 over a large portion of North America, trapping warm air near the surface. As air sinks through the atmosphere, it compresses and heats further, enabling abnormally high temperatures to develop.
