Arctic Blast Tightens Hold on the Great White North as US Records Hottest Christmas on Record.
An intense cold spell has seized a severe and lengthy Arctic outbreak, with readings persisting between -20C and -40C for an extended duration. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, representing its most frigid December day in nearly five decades.
Enduring Chill Below -40C
Similarly, the communities of Mayo and Dawson experienced over two straight weeks of nights below -40C, with the temperature in Mayo bottoming out at -50.4 degrees Celsius on Monday. Whitehorse similarly reported 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 lows of at least -20C across many regions, from Edmonton in the west to Quebec in the east.
Forecast to Persist For Days to Come
The frigid conditions are predicted to linger for the foreseeable future. There are warnings of possible electrical grid strain in Yukon territory over the next several days, as its energy infrastructure faces unprecedented demand from record-high energy demand.
This extended freeze is the result of a stationary polar vortex across the northern part of the continent this month, enabling a surge of icy Arctic winds to descend. Next week, the cold air mass is expected to retreat north slowly, permitting warmer Pacific winds to flow over the United States and penetrate southern Canadian regions.
Dramatic Difference Compared to Stateside Temperatures
Meanwhile, in a dramatic contrast, areas of the United States saw the hottest December 25th in their history as readings skyrocketed 15 to 30 degrees Celsius above normal. For numerous locations, the weather resembled a spring day in April or May instead of the heart of winter.
A number of states broke historical records for December 25th warmth. The capital of Oklahoma soared to 25C on Christmas Day, exceeding the old record of 22C from 1982. Metropolitan areas such as Austin, Dallas, and Charlotte similarly saw thermometers rise past the 25C mark.
High-Pressure System Drives the Heat
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 unseasonable temperatures are powered by a strong upper-level ridge reaching from the arid southwest across the continent, establishing a classic heat-dome pattern. Such a configuration results in a widespread high-pressure system over a large portion of North America, effectively capping warm air at lower altitudes. Sinking atmospheric air undergoes compression and additional heating, enabling abnormally high temperatures to develop.
