The polar vortex is very weak, there is a risk of a freezing winter like in 1981

The polar vortex is struggling to restart this year. We are talking about a vast area of ​​low pressure that rotates above the North Pole, and represents one of the main climatic phenomena that determine …

The polar vortex is very weak, there is a risk of a freezing winter like in 1981

The polar vortex is struggling to restart this year. We are talking about a vast area of ​​low pressure that rotates above the North Pole, and represents one of the main climatic phenomena that determine the weather in Europe during the winter months. A strong vortex brings with it mild temperatures and little precipitation, while a weak vortex usually means freezing air and extreme weather events. This year’s, for now, is the weakest for about 40 years, and according to experts it could be the sign of a trend that will dominate the entire winter season, which in turn could herald a very cold winter, like they hadn’t been seen in Europe since 1981.

The polar vortex

The polar vortex, as we were saying, is a vast low pressure area located above the North Pole (there is a twin at the South Pole which, however, does not directly influence the weather in Europe). It has a cyclonic structure, and rotates counterclockwise within the latitudes delimited by the polar jet streams, it strengthens in autumn and then tends to decrease in intensity at the end of winter. It is traditionally divided into a stratospheric portion (between 15 and 50 kilometers above sea level), which has a greater influence on long-term weather conditions, and a tropospheric portion more directly connected with short-term weather.

The important characteristic of the polar vortex is that the stronger it is, the more it tends to keep the freezing air of the Arctic regions inside it. A weak vortex instead tends to give cold air masses the opportunity to escape towards the more southern regions, thus lowering the temperatures of Western Europe, even up to the latitudes of Central and Southern Italy.

Well, so what is the situation today? At the moment, the polar vortex is small in size and strength, unstable, and somewhat out of position, biased towards Siberia. Since we are still in October, there are currently no large masses of cold air that could change the European climate.

polar vortex situation

If the situation were to reoccur in the next few months, however, the consequences could be felt, and with a bang. In fact, a situation similar to the current one has not been seen since October 1981, when the winter season proved to be one of the coldest ever, with temperatures reaching -25 degrees in the United Kingdom, and heavy snowfalls and frosts also in our latitudes.

However, climate patterns are extremely complex to understand and even more so to predict, thanks to climate change and the effects of global phenomena such as El Niño. It is therefore difficult to predict what will happen in the coming months, except – perhaps – based on the trends of recent years.

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“The polar vortex is often weak in these years” explains Giulio Betti, climatologist of the Cnr and the LaMMA consortium – while the tropical band is stronger and more extensive, therefore it is more likely to have mild winters but with short and intense cold waves, rather than long, cold winters with rare mild breaks.”