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An intense cold spell has seized a severe and lengthy Arctic outbreak, with readings persisting in the minus 20 to minus 40 Celsius range for an extended duration. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, representing its most frigid December day since 1975.

Consecutive Nights 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 Mayo plunging to -50.4C at the start of the week. The capital, Whitehorse, likewise saw ten separate nights when the cold dipped under -30 Celsius.

The deep freeze spread farther south during the holiday season. Christmas night saw Edmonton's temperatures plummet below minus 28C.

The day after Christmas was forecast to deliver lows of at least -20C through a wide swath, from Edmonton in the west to Quebec in the east.

Likely to Linger into the New Year

The severe cold is forecast to persist through the start of January. Authorities have cautioned about potential power failures in the Yukon soon, as its energy infrastructure faces unprecedented demand from record-high energy demand.

The lengthy cold snap originates from a stationary polar vortex above Canadian territory through December, which funnels frigid northern air southward. 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.

Dramatic Difference to American Heat

Conversely, sections of America recorded historically high temperatures for Christmas as readings skyrocketed 15 to 30 degrees Celsius above normal. Across wide regions, the atmosphere was more akin to late spring instead of the heart of winter.

Multiple states established new Christmas temperature highs. In Oklahoma, Oklahoma City hit 25C on Tuesday, topping the prior high mark of 22 degrees established over forty years ago. Metropolitan areas such as Austin, Dallas, and Charlotte similarly saw thermometers rise past the 25C mark.

Atmospheric Ridge Fuels Warmth

Warmer-than-normal conditions are forecast to last through Boxing Day and the days ahead, with unseasonable heat forecast to sweep across the southeastern US in the coming days.

The unseasonable temperatures are powered by a robust atmospheric ridge reaching from the arid southwest across the continent, creating a heat-dome effect. This pattern establishes a broad area of high pressure across much of the continent, effectively capping warm air at lower altitudes. Descending air compresses and adiabatically warms, enabling abnormally high temperatures to develop.