Will El Niño and the polar vortex bring snow to the UK this winter?
BBC Lead Weather Presenter Ben Rich explores the complex links between El Niño, the polar vortex, and winter snow forecasts in the UK.
Stock photo for illustration only, not from the actual event
- Rumours of widespread UK snow driven by a polar vortex and El Niño involve complex meteorological factors.
- El Niño increases the probability of wet, mild, and stormy weather across the UK during the autumn months.
- The polar vortex is a belt of strong westerly winds circling the North Pole high up in the stratosphere.
- Disruptions to the polar vortex and El Niño impacts in late winter could tilt the odds toward cold weather, but nothing is guaranteed.
Headlines have frequently suggested that widespread snow driven by a polar vortex is heading for the UK this autumn and winter, but the meteorological reality is far more complicated. Throughout the remainder of the autumn season, the El Niño phenomenon actually increases the probability of experiencing wet, mild, and potentially stormy weather conditions across the United Kingdom.
Later in the winter season, these patterns could shift the odds toward cold spells and snow, a shift that can be influenced by fluctuations in the polar vortex, though none of these outcomes are certain. The polar vortex is defined as a ring of powerful westerly winds that encircle the North Pole every winter, operating at altitudes roughly 10 to 30 miles or 16 to 48 kilometers above the Earth's surface. It forms because the air high above the polar region becomes exceptionally cold and dense during the winter months, creating a sharp temperature contrast with warmer air further south that drives these intense stratospheric winds.
Stock photo for illustration only, not from the actual event
While the terms polar vortex and El Niño frequently make headlines during discussions of severe seasonal weather, meteorologists emphasize that events occurring high up in the stratosphere do not always directly translate into immediate surface-level weather changes without complex atmospheric interactions.
All of this dynamic activity takes place high up in the stratosphere, far above the troposphere where our everyday weather actually occurs. A robust and strong polar vortex tends to encourage a similarly strong polar jet stream down in the troposphere, which drives areas of low pressure from west to east and usters mild Atlantic air across the UK accompanied by spells of wind and rain while locking the coldest air away to the north.
At times, however, the polar vortex can wobble, weaken, or even reverse its direction entirely. Over periods spanning days and weeks, this disturbance can work its way down through the atmospheric layers to influence our jet stream, causing it to weaken, become more meandering, or reverse course, which can deliver colder northerly or easterly winds responsible for the UK's most severe winter weather.
"Disruptions to the polar vortex can cause the jet stream to change shape increasing the chance of cold winter weather affecting the UK."
Ben Rich, BBC Lead Weather Presenter
Nevertheless, these stratospheric shifts do not always translate into predictable weather pattern changes at the Earth's surface. Equally, periods featuring a meandering jet stream and cold winter weather frequently occur without any significant alterations taking place in the polar vortex. Meanwhile, El Niño, the naturally occurring climate phenomenon located in the Pacific Ocean, continues to develop and by certain measurement metrics is already recorded as the strongest on record.
The heat released from the warming Pacific Ocean into the atmosphere impacts global weather patterns significantly. In autumn, it heightens the chance of wet and stormy weather in the UK, a trend reflected in seasonal forecasts. By late winter, waves of energy released by El Niño can travel upwards through the atmosphere, making it more probable that the polar vortex will become disrupted, thereby raising the likelihood of ice and snow.
Despite these mechanisms, the exact links remain unclear and observational evidence is mixed. The notorious Big Freeze of 2009/2010 was at the time the coldest winter recorded in three decades and coincided directly with an El Niño event. Conversely, the 2006/2007 winter also occurred during an El Niño phase yet proved unseasonably warm, while the Beast from the East in 2018 struck during a La Niña year, the functional opposite of El Niño.
Consequently, while El Niño is exerting major impacts on global weather systems and may influence the polar vortex later in the winter, snow and ice in the UK remain far from guaranteed. Current weather forecasts indicate that no significant cold spells or snow events are likely in the immediate future.
Source: BBC Science & Environment
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