While the rest of the USA experiences at Christmas 2021 with abnormally warm, in south-central parts even tropical weather, with wildfires and after Christmas, the next tornado outbreak in Midwest and Southeast is possible /https://mkweather.com/chicago-with-the-latest-first-snowfall-in-history/; https://mkweather.com/the-warmest-christmas-in-history-the-usa-hit-tropical-heatwaves-farms-and-ranches-in-texas-are-in-fire/; https://mkweather.com/after-the-christmas-heatwave-the-next-possible-tornado-outbreak-in-the-usa-between-28-31-december-2021/; https://mkweather.com/breaking-ef4-tornado-in-kentucky-killed-50-people-it-was-historic-winter-supercell/; https://mkweather.com/record-heatwaves-the-strongest-storms-since-2004-and-the-next-tornado-outbreak-december-in-the-usa/; https://mkweather.com/the-first-december-tornado-outbreak-in-minnesota-in-all-time-history-7-tornadoes-caused-damages//, extremely cold air from Western Canada has already shifted above Northwest, USA, with rare white Christmas in parts of the region, including metropolitan areas.
Surprising should be mainly forecast snowfall for Portland, Oregon capital, where the last time white Christmas appeared in 2008.
Meanwhile, the city of Geroge, British Columbia, Canada, received according to weather news a record 24-snowfall in history, with fresh 13.8 inches / 35 cm before Christmas.
Minimum temperatures in Deadmen Valley and Rabbit Kettle, Northwestern Territory, a province northward from British Columbia, NW Canada, dropped to -45,8°C / -50.4°F at Christmas, which is the strongest frost in the region in Winter 2021/2022, so far.
Fort Yukon, Alaska, reported -40,6°C / -41.1°F at Christmas 2021.
Just from these parts of the continent is flowing anomalously cold air above Northwest, the USA, with a result of minimum temperatures in Portland on 24. and 25. December 2021 -10,6°C / 12.9°F and -10,0°C / 14°F and 20. and 21. December 2021 -13,9°C / 7°F and -12,2°C / 10°F, at Christmas with all-day frosts (ice days) and snowing.
In Seattle, snowflakes appeared on 20. December 2021, near the minimum temperature of +0,6°C / 33.1°F.
Surprisingly cold is Caribou, northernmost Northeast, the USA, too, with a minimum temperature of -22,2°C and an Arctic day with a maximum temperature of only -10,0°C / 14°F on 25. December 2021.
A belt of winter conditions is bringing cold weather in the northern USA mainly along the Canadian border and chances for the white Christmas are in the Rocky Mountains, too.