Arctic Blast Tightens Hold on Canada as United States Experiences Warmest Christmas Ever.
An intense cold spell has seized a severe and lengthy Arctic outbreak, with thermometers lingering from 20 to 40 degrees below zero for weeks. On Tuesday, Braeburn in the Yukon recorded -55.7C, its coldest December temperature since 1975.
Consecutive Nights Below -40C
Meanwhile, Mayo and Dawson endured sixteen nights in a row dipping under the minus 40 Celsius threshold, with Mayo experiencing a low of -50.4C earlier this week. The capital, Whitehorse, likewise saw 10 nights when the cold dipped under -30 Celsius.
This Arctic air mass pushed further southward through Christmas week. On Christmas Day, overnight temperatures in Edmonton fell below -28C.
The day after Christmas was forecast to deliver lows of at least -20C through a wide swath, encompassing cities from Edmonton to Quebec.
Expected to Continue Through Early January
The frigid conditions are predicted to linger into the new year. Officials have warned that the Yukon could face electricity outages over the next several days, as the territory’s power grid comes under strain from historically high electricity consumption.
This extended freeze is the result of the polar vortex remaining anchored over Canada for much of December, allowing bitter Arctic air to spill south. The frigid dome is projected to gradually withdraw north allowing more temperate air from the Pacific to sweep across America and reach into portions of southern Canada.
Stark Contrast to American Heat
Conversely, sections of America recorded historically high temperatures for Christmas as temperatures soared about 15-30C above the seasonal average. In many areas, conditions felt more typical of April or May rather than the end of December.
A number of states broke historical records for December 25th warmth. Oklahoma City, Oklahoma, reached 25 degrees Celsius on Christmas, topping the prior high mark of 22 degrees established over forty years ago. Metropolitan areas such as Austin, Dallas, and Charlotte also logged readings above 25 degrees Celsius.
High-Pressure System Sustains High Temperatures
Warmer-than-normal conditions are forecast to last on December 26th and into the weekend, with unseasonable heat forecast to sweep across the southeastern US in the coming days.
The warmth has been fuelled 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 over a large portion of North America, which holds warm air close to the ground. Sinking atmospheric air undergoes compression and additional heating, fostering the buildup of exceptional warmth.
