Prolonged Chill Tightens Hold on Canada as United States Experiences Most Unseasonably Mild Christmas on Record.
A prolonged deep freeze has enveloped a severe and lengthy Arctic outbreak, with thermometers lingering between -20C and -40C for multiple weeks. On Tuesday, Braeburn in the Yukon recorded -55.7C, representing its most frigid December day since 1975.
Enduring Chill in the Deep Minus Forties
In addition, the locales of Mayo and Dawson suffered through 16 consecutive nights below -40C, with the temperature in Mayo bottoming out at -50.4 degrees Celsius at the start of the week. Whitehorse similarly reported 10 nights when temperatures dropped below -30C.
This Arctic air mass pushed further southward through Christmas week. 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.
Expected to Continue into the New Year
This harsh winter weather is expected to continue into the new year. There are warnings of possible electrical grid strain in Yukon territory soon, as the system endures record-high pressure from record-high energy demand.
The prolonged chill has been caused by the polar vortex remaining anchored over Canada for much of December, allowing bitter Arctic air to spill south. Next week, the cold air mass is expected to retreat north gradually, enabling milder Pacific air to move across the United States and penetrate southern Canadian regions.
Dramatic Difference Compared to Stateside Temperatures
Conversely, sections of America recorded the hottest December 25th in their history as the mercury climbed roughly 15 to 30 degrees above typical averages. Across wide regions, the atmosphere was more akin to late spring instead of the heart of winter.
Multiple states established new Christmas temperature highs. Oklahoma City, Oklahoma, reached 25 degrees Celsius on Christmas, topping the prior high mark of 22 degrees established over forty years ago. Cities including Austin and Dallas, in Texas, and Charlotte, North Carolina also logged readings above 25 degrees Celsius.
Atmospheric Ridge Sustains High Temperatures
Unseasonable heat is predicted to persist on December 26th and into the weekend, with atypical high temperatures expected to spread across the southeastern US in the coming days.
The warmth has been fuelled by a strong upper-level ridge stretching from the southwestern deserts northward and eastward, which generates a heat-dome phenomenon. Such a configuration results in a widespread high-pressure system blanketing a significant part of the landmass, trapping warm air near the surface. As air sinks through the atmosphere, it compresses and heats further, enabling abnormally high temperatures to develop.
