What the Polar Vortex Could Mean for UK Weather This Autumn and Winter
A record-strength El Niño is raising talk of a polar vortex breakdown and a cold late winter in the UK. Here is what the Met Office says and how to prepare.
The Met Office has warned that an unprecedented El Niño could shape the weather this autumn and winter. Headlines have linked the event to a possible deep freeze, but the forecasters' own message is more cautious.
What the polar vortex is
The polar vortex is a band of strong westerly winds circling the North Pole. It keeps very cold air trapped near the Arctic. When it weakens or is disrupted, it becomes "wavy" and cold air can spill south into Europe and North America, according to the Evening Standard.
A research paper from the US NOAA Chemical Sciences Laboratory, cited by the Standard, found that El Niño "tends to promote the breakdown of the polar vortex, especially in late winter".
What the Met Office says
El Niño is a natural climate pattern in which the tropical Pacific Ocean warms. The Met Office says the current one is unprecedented in strength, has already passed previous records and is expected to peak later this year. Seasonal models point to a peak in November or December.
For the UK, the Met Office says this raises the chances of a wetter and stormier late autumn and early winter, which would probably also be milder than normal. Chief forecaster Dr Will Lang called it a "subtle shift in the odds" rather than a certainty. He said the risk includes a "heightened potential for flooding".
After the peak, the stratospheric polar vortex can weaken. That raises the chance of Sudden Stratospheric Warming (SSW) events, which in turn increase the potential for cold weather in the latter part of winter. LBC describes SSW as warming high in the atmosphere, between 10km and 50km up, that can "block" the jet stream.
Professor Adam Scaife, the Met Office's Head of Long Range Prediction, said scientists are still assessing whether impacts will match the El Niño's size. The Met Office also stresses that El Niño alone does not determine exact weather patterns.
How to prepare
British Gas has issued cold-weather advice, which the Standard reported in the context of heavy snow. It suggests:
- Keeping at least three days of food and essentials in an easy-to-reach spot.
- Including medicines, drinking water, non-perishable food, snacks and extra blankets in an emergency kit.
- Improving home insulation and protecting pipes against freezing.
- Checking your car's brakes, heater, tyres and windscreen wipers, and keeping the fuel tank half full in snowy conditions.
- Checking on elderly or vulnerable relatives and neighbours.
Note that the "stockpile" framing comes from the Standard's headline. The advice itself is about having a few days of basics to hand, not panic buying.
Also read Small Tornado Hits Ulladulla on NSW South Coast, Damaging Homes and Toppling Trees
What it means for you
The nearer-term risk in the Met Office's outlook is wet and stormy weather this autumn, including possible flooding, rather than snow. A colder spell is a possibility later in winter, not a forecast. The sensible step now is to check pipes, insulation and your car before the cold arrives, and to keep an eye on Met Office forecasts and warnings as winter approaches.
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