Deep Freeze Envelops Canada as United States Experiences Most Unseasonably Mild Christmas Ever.
An intense cold spell has seized a severe and lengthy Arctic outbreak, with readings persisting in the minus 20 to minus 40 Celsius range for weeks. A reading of -55.7 Celsius was logged in Braeburn, Yukon, on Tuesday, representing its most frigid December day in half a century.
Enduring Chill of Extreme Cold
Similarly, the communities of Mayo and Dawson experienced 16 consecutive nights colder than minus 40 degrees, with the temperature in Mayo bottoming out at -50.4 degrees Celsius earlier this week. The capital, Whitehorse, likewise saw ten separate nights when the cold dipped under -30 Celsius.
This Arctic air mass pushed further southward over the festive period. In Edmonton, the Christmas overnight low dipped under -28 degrees Celsius.
Boxing Day was expected to bring readings no higher than -20 Celsius through a wide swath, including Edmonton, Montreal, Ottawa and Quebec.
Forecast to Persist into the New Year
The severe cold is forecast to persist through the start of January. Authorities have cautioned about potential power failures in the Yukon in the coming days, as the territory’s power grid comes under strain from historically high electricity consumption.
The prolonged chill has been caused by the Arctic vortex settling over Canada for much of December, which funnels frigid northern air southward. The frigid dome is projected to gradually withdraw north gradually, enabling milder Pacific air to move across the US and into parts of southern Canada.
Stark Contrast with US Warmth
In stark contrast, parts of the US experienced their warmest Christmas Day on record as temperatures soared about 15-30C above the seasonal average. In many areas, conditions felt more typical of April or May instead of the heart of winter.
Several states set Christmas Day temperature records. The capital of Oklahoma soared to 25C on Christmas Day, surpassing the previous peak of 22C set in 1982. Cities including Austin and Dallas, in Texas, and Charlotte, North Carolina also logged readings above 25 degrees Celsius.
High-Pressure System Drives the Heat
Warmer-than-normal conditions are forecast to last for the remainder of the week and beyond, with atypical high temperatures expected to spread across the southeastern US in the coming days.
The warmth has been fuelled by a robust atmospheric ridge extending from the desert south-west towards the north and east, creating a heat-dome effect. This setup creates an extensive zone of high atmospheric pressure over a large portion of North America, effectively capping warm air at lower altitudes. Descending air compresses and adiabatically warms, enabling abnormally high temperatures to develop.
