UK extreme weather alert as Polar Vortex leaves Britain facing deep freeze

UK extreme weather alert as Polar Vortex leaves Britain facing deep freeze A polar vortex forming over the North Pole could be sent Britain's way, leading to a deep freeze this winter, experts have said A record-breaking El Niño could disrupt a polar vortex forming over the North Pole, sending Britain into a deep freeze this winter. El Niño, a weather event developing over the tropical Pacific Ocean, can influence weather patterns thousands of miles away - including the "stratospheric polar vortex", a huge mass of cold air and strong winds spinning high above the Arctic that develops during autumn. The Met Office said on Tuesday that this year's El Niño is set to be the strongest event in the observational record - and likely the strongest since the 19th century. El Niño increases the chances of wetter and stormier conditions across north-west Europe, including the UK, during autumn and early winter, while also increasing the risk of cold snaps later in the season. The so-called "Big Freeze of 2010" - during which the winter 2009-2010 was at the time the coldest in three decades - coincided with an El Niño. El Niño "tends to promote the breakdown of the polar vortex, especially in late winter", a research paper published by the US NOAA Chemical Sciences Laboratory concluded. The polar vortex is a band of strong westerly winds that circles around the North Pole high in the stratosphere that traps bitterly cold air near the Arctic. However, a weakened or disrupted vortex becomes "wavy" and allows freezing air to spill southward into mid-latitude regions like North America and Europe. El Niño primarily influences the polar vortex by triggering a sudden stratospheric warming (SSW) - a dramatic winter event in which temperatures high up in the stratosphere can rise very rapidly, by as much as 50C over just a few days. The Met Office says several extreme cold and winter snow events have been connected to the surface effects of sudden stratospheric warmings, such as those in 2009-10 and 2013, as well as "The Beast from the East" in 2018. It comes as the Met Office said on Tuesday that the latest observations confirm sea-surface temperatures in the central equatorial Pacific have now surpassed levels recorded during any previous event, backing assessments that 2026 could see an unprecedented El Niño. "This milestone represents a significant moment and is likely to have far-reaching impacts on weather patterns around the world," the Met Office said in a press release. Professor Adam Scaife, head of long-range prediction at the Met Office, said: "We have been signalling for months that the developing El Niño will be an unprecedented event. "The fact that it has already exceeded previous records - with several weeks to go before it peaks later this year - shows the enormity of this El Niño. Scientists are still assessing whether the impacts will be in proportion to its magnitude, but we are already seeing expected effects worldwide." While El Niño is associated with cold spells in the late winter, some scientists say past evidence is mixed, noting that 2006-2007 was also an El Niño winter and was unseasonably warm. Strong El Niño events are typically associated with a rise in global average temperature because additional heat is released from the ocean into the atmosphere which then spreads around the globe, further warming other ocean basins. As a result, exceptionally strong El Niño events can contribute to record-breaking global temperatures in the year following their peak. The current event is developing against a backdrop of long-term human-induced climate change, meaning its effects are superimposed on an already warming climate.