Climate experts have observed an exceptionally early disruption of the polar vortex, an area of low atmospheric pressure located above the poles, a phenomenon whose consequences are still „uncertain” for the weather conditions in Europe.
The polar vortex is a vast phenomenon consisting of very strong winds, which occur at altitudes between 10 and 50 kilometers above the Arctic during the winter of the northern hemisphere. Variations in its intensity and configuration (shape, temperature, etc.) can have consequences on the weather in Europe, causing, for example, a significant drop in temperatures, meteorological agencies from France and the United Kingdom told AFP.
"Computer models indicate a major disruption of the vortex in the upper atmosphere (between 10 and 50 kilometers altitude) at this beginning of November," which "has not occurred before the end of November (...) since the 1950s," Météo France reported.
This disruption most often occurs in January or February.
Such earliness "is exceptional," said Grahame Madge, spokesperson for the UK's Met Office. A possible explanation would be "the amplitude of the El Nino phenomenon in the Pacific" this year, he added.
The Met Office explained that a weakening of the vortex, caused mainly by stratospheric warming, can increase the likelihood that colder air will descend from the Arctic southward, as well as cause a disruption of the westerly wind patterns, leading to drier weather.
At this moment, Météo France estimates that the consequences for the weather remain "very uncertain" in France and "will depend on how the disruption evolves."
The phenomenon could "increase in the coming weeks" the temperature differences between northern and southern Europe, with colder weather in the north and warmer in the south, the French agency added.
However, this earliness could also generate "less marked" effects than when the disruption occurs in the middle of winter, Grahame Madge specified.
"Indeed, temperatures in the regions that represent the source of these air masses, such as Siberia and the Arctic, are not yet as low as those that will exist in February," he explained.
Also, "a certain number of elements will need to manifest in a precise order for us to feel the effects, and such an evolution is by no means guaranteed," added the Met Office spokesperson.