Arctic Blast Tightens Hold on the Great White North as America Sees Most Unseasonably Mild Christmas in History.
A prolonged deep freeze has enveloped a bitter and extended period of frigid weather, with readings persisting in the minus 20 to minus 40 Celsius range for an extended duration. On Tuesday, Braeburn in the Yukon recorded -55.7C, its coldest December temperature in half a century.
Consecutive Nights Below -40C
Meanwhile, Mayo and Dawson endured sixteen nights in a row colder than minus 40 degrees, with Mayo plunging to -50.4C earlier this week. Whitehorse similarly reported a series of ten nights when temperatures dropped below -30C.
The deep freeze spread farther south during the holiday season. On Christmas Day, overnight temperatures in Edmonton fell below -28C.
Boxing Day was expected to bring minimum temperatures of at least minus 20C through a wide swath, from Edmonton in the west to Quebec in the east.
Likely to Linger into the New Year
This harsh winter weather is expected to continue 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 peak power usage levels.
This extended freeze is the result of the polar vortex remaining anchored above Canadian territory through December, enabling a surge of icy Arctic winds to descend. 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.
Pronounced Disparity Compared to Stateside Temperatures
In stark contrast, parts of the US experienced their warmest Christmas Day on record 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.
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. Urban centers like Austin, Dallas, and Charlotte, North Carolina were also among those that recorded temperatures above 25C.
High-Pressure System Drives the Heat
Warmer-than-normal conditions are forecast to last for the remainder of the week and beyond, with unseasonable heat forecast to sweep across the southeastern US in the coming days.
The unseasonable temperatures are powered by a strong upper-level ridge reaching from the arid southwest across the continent, creating a heat-dome effect. Such a configuration results in a widespread high-pressure system across much of the continent, trapping warm air near the surface. Sinking atmospheric air undergoes compression and additional heating, enabling abnormally high temperatures to develop.