Prolonged Chill Envelops the Great White North as America Sees Most Unseasonably Mild Christmas in History.
A prolonged deep freeze has enveloped a severe and lengthy Arctic outbreak, with thermometers lingering in the minus 20 to minus 40 Celsius range for weeks. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, marking its chilliest December reading in nearly five decades.
Prolonged Freeze Below -40C
Meanwhile, Mayo and Dawson endured 16 consecutive nights below -40C, with Mayo experiencing a low of -50.4C on Monday. Whitehorse also recorded 10 nights when the cold dipped under -30 Celsius.
The deep freeze spread farther south through Christmas week. Christmas night saw Edmonton's temperatures plummet below minus 28C.
Boxing Day was expected to bring minimum temperatures of at least minus 20C through a wide swath, including Edmonton, Montreal, Ottawa and Quebec.
Forecast to Persist For Days to Come
The severe cold is forecast to persist for the foreseeable future. Authorities have cautioned about potential power failures in the Yukon soon, as its energy infrastructure faces unprecedented demand from historically high electricity consumption.
The prolonged chill has been caused by the polar vortex remaining anchored above Canadian territory through December, which funnels frigid northern air southward. Next week, the cold air mass is expected to retreat north allowing more temperate air from the Pacific to sweep across the US and into parts of southern Canada.
Pronounced Disparity to American Heat
In stark contrast, parts of the US experienced 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 than late December.
Several states set Christmas Day temperature records. 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 Sustains High Temperatures
Above-average warmth is expected to continue for the remainder of the week and beyond, with atypical high temperatures expected to spread into the south-eastern states later in the week.
The warmth has been fuelled by a robust atmospheric ridge extending from the desert south-west towards the north and east, which generates a heat-dome phenomenon. Such a configuration results in a widespread high-pressure system over a large portion of North America, effectively capping warm air at lower altitudes. Descending air compresses and adiabatically warms, fostering the buildup of exceptional warmth.
