Polar vortex disruption and cold wave risk, Digi Mart USA News: Meteorologists said on Friday they had observed an exceptionally early disruption of the polar vortex, a development that increases the risk of cold waves across the Northern Hemisphere, although the consequences remain uncertain.
The polar vortex is a large region of very strong winds circulating between 10 and 50 kilometers above the Arctic during the Northern Hemisphere winter. Changes in its intensity and shape, as well as its temperature, can affect weather and lead to significant drops in temperature.
These winds typically strengthen in autumn and peak in January.
The polar vortex can weaken in the second part of winter, generally between January and March, allowing extremely cold air to move south and reach Europe, North America and Asia. According to scientists, however, the vortex is already weakening in early November.
“To our knowledge, this is the earliest stratospheric vortex disruption ever observed,” Tim Stockdale and Frederic Vitart of the European Centre for Medium-Range Weather Forecasts (ECMWF) told AFP.
The disruption “considerably increases the risk of cold waves in the most populated regions of the Northern Hemisphere, the United States, Europe and East Asia,” said Judah Cohen, a climatologist at the Massachusetts Institute of Technology, speaking to AFP. Grahame Madge, a spokesperson for the British Met Office, described the timing as “exceptional,” and suggested a possible explanation could be the strength of the El Niño phenomenon in the Pacific this year.
For Switzerland, the polar vortex acts somewhat like a barrier that keeps icy air near the North Pole. When it weakens, that barrier can become less effective and allow cold air to move south.
Switzerland could then see lower temperatures or episodes of bise, the cold northeasterly wind, but this does not necessarily mean snow will fall, as much will depend on how conditions evolve in the coming weeks.
A weakened polar vortex can change atmospheric wind patterns and favor the arrival of cold air in Europe, but its effects are neither immediate nor systematic, and precise forecasts remain difficult. This evolution may favor weather patterns lasting several days and easterly winds capable of bringing cold air, though this does not mean a cold wave or snowfall will necessarily reach Switzerland.
In the short term, a slight warming is expected, with temperatures possibly reaching 15 degrees Celsius in the Lake Geneva arc by the middle of next week. Whether the early disruption will bring particularly cold winter episodes will only become clear in the weeks ahead.
