The Met Office has issued a fresh assessment on the likelihood of snow hitting the UK earlier than expected this winter, following a 'disturbance' at the North Pole that could trigger a Polar Vortex. While snowfall remains unconfirmed, weather experts have revealed that a stratospheric polar vortex high above the North Pole is 'currently being disturbed'. This has shown evidence of 'sudden stratospheric warming' that could bring colder conditions, including fog, frost and even snow. The reports come as the UK could face snow in November, with temperatures for some areas potentially plummeting to -7°C.
Exceptional Development Early in the Season
Meteorologists have described this as an 'exceptional development for this early in the season', suggesting it could be connected to the ongoing El Niño weather phenomenon in the Pacific. The Met Office stated: "But could events thousands of kilometres away, and tens of kilometres above our heads, eventually influence the UK's weather?". "The answer involves a fascinating chain of interactions across the atmosphere."
"During autumn, the stratosphere above the North Pole becomes increasingly cold as the Northern Hemisphere receives less sunlight. The growing temperature contrast between the Arctic and lower latitudes helps strengthen a ring of westerly winds around the pole, known as the stratospheric polar vortex." The Met Office added: "The stratospheric polar vortex high above the North Pole is currently being disturbed, with signs that a sudden stratospheric warming (SSW) is developing. It is an exceptional development for this early in the season and there is an intriguing connection with the current exceptional El Niño in the tropical Pacific."
El Niño's Role in the Chain of Events
Met Office presenter and meteorologist Aidan McGivern explained: "El Niño is basically enhancing the waves that go on in the troposphere, the wriggly jet stream. Those waves can then propagate upwards into the stratosphere, knocking, bumping and disturbing that circle of winds around the polar stratosphere, causing it to be displaced, pushed off the pole, deformed or even split."
The Met Office describes this as a good example of a "teleconnection", where atmospheric changes in one part of the world influence weather patterns thousands of kilometres away. The current disturbance is already producing warming in the stratosphere above the North Pole, according to reports from the Express. Forecasts now show temperatures continuing to rise, while the normally westerly winds surrounding the vortex weaken.
Monitoring the Polar Vortex
Should this phenomenon occur, its timing would be particularly remarkable, the forecaster notes, adding: "It would be exceptionally early in the season compared with the events meteorologists are more accustomed to analysing later in winter." McGivern further stated: "We know that El Niños increase the chances, through this chain of events, of sudden stratospheric warmings happening, and we know sudden stratospheric warmings increase the chance of colder weather for the UK. So we've got this chain of events that we can start to flag well in advance."
The Met Office states: "High pressure over the UK could bring quieter, drier conditions with an increased likelihood of frost and fog. Blocking farther north could encourage easterly winds, while high pressure to the west could make northerly winds more likely. Historically, an SSW increases the chance of colder UK weather, but the outcome is far from guaranteed." That uncertainty is particularly important with such an early-season event because there is generally less cold air available across the Northern Hemisphere than later in winter. For now, therefore, this is not a forecast of an impending UK cold spell; instead, meteorologists will be closely monitoring the polar vortex and whether changes in the stratosphere eventually work their way down into the part of the atmosphere where day-to-day weather takes place.
