Meteorological models indicate an unusually early weakening and disruption of the polar vortex, which could fundamentally affect the course of the beginning of this winter. According to the latest long-term forecasts, an early episode of stratospheric warming (a sharp increase in temperature and pressure in the stratosphere) is forming in the stratosphere, which can trigger significant changes in air circulation and release arctic cold to lower latitudesreports the website.
Models for the first half of December (beginning of meteorological winter) show a scenario typical of a weakened polar vortex: blocking over Greenland, drop in pressure over the Arctic, significant descent of cold Arctic air into the middle latitudes.
For North America, this means an increased risk of early Arctic incursions. Forecasts indicate a massive cold wave from southern Canada to much of the northern, central and eastern US. The models also expect above-average snow totals.
Europe may also feel the cooling, especially its northern, central regions and the UK, according to several simulations. However, some models see the cold air moving mainly to northern and northeastern Europe, while others show a wider impact also in central Europe, where Slovakia is located.
The Canadian CanSIPS system, as well as the American GEFS models and other European forecasts, agree in one thing: early December has a high chance of being colder than normal with the possibility of earlier snowfall especially in North America and some parts of Europe.
What is the polar vortex and why is it important?
The polar vortex is a large vortex of cold air in the Arctic region that extends from the troposphere high into the stratosphere. When it is strong and compact, it keeps the arctic cold locked above the pole and brings rather milder winters to the mid-latitudes. However, if it weakens or breaks, cold air can more easily escape to the south – to the USA, Canada or Europe.
