Christmas 2021 forecast: Negative phase of Arctic Oscillation?




Already in the last Christmas forecasts for Europe and North America (and partially for Asia and North Africa), we forecasted warm Christmas in eastern parts of the USA or Canada, while Europe appeared warm in north and west and cold in east and south /https://mkweather.com/forecast-for-christmas-2021-in-the-usa-canada-and-mexico-the-first-preliminary-estimates-a-possible-warm-weather-in-eastern-and-southern-and-colder-weather-in-northern-and-western-parts/; https://mkweather.com/forecast-for-christmas-2021-in-europe-the-first-preliminary-estimates-a-possible-warm-weather-in-northern-and-western-and-colder-in-southern-and-eastern-europe/; https://mkweather.com/the-1st-forecast-for-christmas-2021-warm-christmas-in-europe-north-america-and-asia//.

Now, on 12. November 2021, the newest 6-week ECMWF forecast until 27. December 2021 is available and it appears, that while Europe should be happy from much more winter-like forecasted conditions, such was forecasted, East Coast, the USA, and Canada appear very warm, probably without snow or frosts in many regions.

It´s a typical AO-phase, or negative phase of Arctic Oscillation, with a shallow Icelandic low and therefore warmer advection on its backside, while the collapse of stormtrack above Eurasian sector, with Mediterranean lows, is bringing significant coldwaves across Europan and Asian mid-latitudes.

Forecast for the week 20.-27. December 2021 from ECMWF for Eurasia counts with a belt of colder air masses above the continent, which should mean AO- conditions.

The warm temperature anomaly above East Coast in North America is long from Mexico to southwestern Greenland, which is too a sign of a minimally NAO- phase (AO- Euroatlantic equivalent).

Christmas 2021 forecast for Europe was therefore changed to cold, maybe only in Portugal, Spain, France, Benelux, Ireland, the UK, or Norway warmer.

Christmas 2021 forecast for North America is staying very similar to previous, while along East Coast should be very warm, the Pacific coast should bother coldwaves.

Asia appears colder or neutral, too, including Siberia, East Asia, or the northern Middle East.

Northwestern Africa should be colder during this period, too.

The next Christmas forecasts should be available around 16. or 20. November 2021, together with the next 6-week ECMWF forecast.

Illustration photo: Temperature anomaly between 20.-27. December 2021 across Northern Hemisphere from ECMWF /https://apps.ecmwf.int/webapps/opencharts/products/extended-anomaly-2t?base_time=202111110000&projection=opencharts_global&valid_time=202112270000/; https://iconscout.com/icon/christmas-tree-pine-xmas-celebration-decoration
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Author: marekkucera
Writer about weather since 2007. The goal of this project is to inform a wide audience about extremes of weather, atmospheric circulation, and climate change around the world. If you like our work, you can support us on Patreon or donate.