Prolonged Chill Tightens Hold on Canada as America Sees Most Unseasonably Mild Christmas Ever.
A prolonged deep freeze has enveloped a severe and lengthy Arctic outbreak, with readings persisting between -20C and -40C for an extended duration. This week, the Yukon community of Braeburn saw the mercury drop to -55.7C, representing its most frigid December day in half a century.
Enduring Chill Below -40C
In addition, the locales of Mayo and Dawson suffered through sixteen nights in a row below -40C, with Mayo plunging to -50.4C on Monday. The capital, Whitehorse, likewise saw 10 nights when readings fell to minus 30 degrees or lower.
The bitter chill extended its reach south through Christmas week. On Christmas Day, overnight temperatures in Edmonton fell below -28C.
December 26th was anticipated to usher in lows of at least -20C through a wide swath, including Edmonton, Montreal, Ottawa and Quebec.
Expected to Continue For Days to Come
The severe cold is forecast to persist for the foreseeable future. There are warnings of possible electrical grid strain in Yukon territory over the next several days, as the territory’s power grid comes under strain 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. The frigid dome is projected to gradually withdraw north slowly, permitting warmer Pacific winds to flow over America and reach into portions of southern Canada.
Pronounced Disparity with US Warmth
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.
A number of states broke historical records for December 25th warmth. In Oklahoma, Oklahoma City hit 25C on Tuesday, exceeding the old record of 22C from 1982. Metropolitan areas such as Austin, Dallas, and Charlotte were also among those that recorded temperatures above 25C.
Atmospheric Ridge Fuels Warmth
Unseasonable heat is predicted to persist through Boxing Day and the days ahead, with unseasonable heat forecast to sweep across the southeastern US in the coming days.
This heat is being driven by a strong upper-level ridge extending from the desert south-west towards the north and east, establishing a classic heat-dome pattern. This setup creates an extensive zone of high atmospheric pressure blanketing a significant part of the landmass, which holds warm air close to the ground. Descending air compresses and adiabatically warms, fostering the buildup of exceptional warmth.
