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Meteorologists say the polar vortex is weakening in early November, the earliest such disruption on record, with uncertainty about its effects on winter weather.
Meteorologists say the polar vortex is weakening in early November, an event they describe as the earliest disruption of its kind on record. The development raises questions about winter weather across the Northern Hemisphere, though experts say the effects remain uncertain.
The polar vortex is a vast region of cold, low-pressure air that normally circulates from west to east high above the Arctic. It generally strengthens through autumn and peaks around January, and can weaken in the second half of winter, typically between January and March.
Scientists say the vortex is already weakening in early November. "As far as we know, this is the earliest stratospheric vortex disruption that has been observed," European Centre for Medium-Range Weather Forecast principal scientists Tim Stockdale and Frederic Vitart told AFP.
The disruption involves sudden stratospheric warming, which weakens or even reverses the vortex's west-to-east winds and can split it apart. The polarvortex.earth dashboard, which visualizes ECMWF modeling, currently shows a full breakdown of the vortex -- when the westerly winds turn easterly -- by November 20.
Reasons for the early disruption are not clear. Grahame Madge, a spokesperson for Britain's Met Office, told AFP: "This is very early, and possibly that earliness is triggered by the amplitude of the El Nino event in the Pacific."
Stockdale and Vitart said they did not know why the disruption came so early, but agreed the El Nino "could have been a factor in making it more likely."
Judah Cohen, a climatologist at MIT, said the current disruption appeared more linked to a record-breaking high-pressure system over Scandinavia and northwestern Russia. Cohen said climate change could be playing a role, though he stressed this was speculation and no research has yet confirmed the link.
The disruption could increase the chance of cold air outbreaks across the Northern Hemisphere. "That really increases the chance of cold air outbreaks across the latitudes where most of the densely populated population centers are across the northern hemisphere, US, Europe and East Asia," Cohen told AFP.
However, because the disruption is coming so early, air temperatures in places like Siberia or over the Arctic are not as cold yet as they will be later in winter, which could make outbreaks less severe. Madge called the event "exceptional" but "not necessarily worrying."
In the UK, Professor Andrew Charlton-Perez, meteorologist at the University of Reading, said: "The typical response to a SSW is for colder and drier conditions over Europe and the UK." He added: "Because we haven't seen a SSW event quite like this before, it is harder to anticipate a cold spell at the moment."
For now, experts stress that it is too early to know whether recent changes in the polar vortex will change the winter outlook.
An early polar vortex disruption is unprecedented in modern observations, and meteorologists have few historical examples to compare with. The event could affect winter weather patterns across Europe, North America and Asia, but the timing, severity and likelihood of cold snaps remain uncertain.
Sources
This article was drafted with AI assistance and checked against the sources above. Company claims are reported as claims. Cover image is AI-generated.
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