A winter full of snow and frost? Meteorologists already know

Although winter is still several months away, meteorologists are already analyzing forecasts for December through February. According to Severe Weather Europe, two key factors could have the greatest impact on the weather during this period: the La Niña anomaly in the Pacific and the expected weakening of the polar vortex.

The co-occurrence of these phenomena may increase the risk of intense inflows of Arctic cold not only to Europe, but also to Asia and North America.

Restless summer, stable winter?

After a turbulent summer that saw rapid changes from heat to cold, and from drought to downpours with the risk of flooding, the end of the year promises to be a bit calmer. According to the Institute of Meteorology and Water Management's seasonal forecast, temperatures are expected to stabilize, although we will still experience alternating periods of dry and wet weather.

A weak La Niña anomaly is predicted to develop in the tropical Pacific during winter. This phenomenon, like its opposite, El Niño, is linked to ocean temperatures. During El Niño, waters in the eastern Pacific are warmer than normal. This, in turn, favors global warming.

La Niña, on the other hand, means colder waters, which also affects weather around the world.

Two phenomena will join forces

Historical data show that La Niña in winter often leads to severe frosts in Canada and the northern US, as well as drought and high temperatures over the Gulf of Mexico. In Europe, these relationships are less clear, but analyses by the European Centre for Medium-Range Weather Forecasts (ECMWF) indicate that in years with La Niña, high-pressure systems were more likely to dominate the Atlantic in late autumn and early winter, while low-pressure systems dominated Russia, which favored the downflow of cold air.

The second important factor is the polar vortex – a widespread stratospheric low that can either trap cold air masses over the Arctic during the winter season or allow them to pass further south. A strong polar vortex, as in the 2019/20 winter, favors warm winters in Europe. A weaker one, on the other hand, facilitates the movement of frost to lower latitudes.

According to Severe Weather Europe, the polar vortex will be weaker than the average for the past three decades in the coming season. Combined with La Niña, this means a greater chance of cold air flowing in from the north, and consequently, more frequent episodes of snowfall and sub-zero temperatures than in recent years.

Experts predict that January, in particular, may bring temperatures close to normal, but with an increased frequency of cold snaps.

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