A powerful atmospheric phenomenon miles above the Arctic has driven some of the most fierce winter storms to hit Britain in recent years, scientists have discovered.
The findings promise to improve long-range forecasts of extreme events such as Storm Eunice, which produced one of the fastest wind gusts ever recorded in England — 122 miles per hour at The Needles on the Isle of Wight.
The study focused on a cluster of powerful storms — Dudley, Eunice and Franklin –— which hit within a single week in February 2022, bringing widespread damage, power outages and the loss of four lives. The month was one of the stormiest on record, with seven named storms affecting the UK.
The researchers, led by Dr Ryan Williams of the University of Leeds, first looked at which forecasts had been most accurate in predicting the worst storms. They saw that the best forecasts had assumed a large influence being played by the so-called stratospheric polar vortex (SPV) — a vast spinning mass of cold air in the stratosphere about 15 miles above the Arctic.
The team then built their own mathematical representations of what was happening in the atmosphere. When they plugged in a more decisive role for the SPV, the results were close to what actually transpired during the destructive February of 2022.
The study suggests that an exceptionally strong vortex made it up to three times more likely that intense storms would develop over the UK and northern Europe. In the presence of such an SPV, the probability of three or more storms striking in a single week increased by 80 per cent, compared with when the vortex was behaving more normally.
Williams said: “Our research demonstrates the need to better understand the different drivers of the North Atlantic storm track, such as the state of the stratospheric polar vortex, which is potentially predictable several weeks in advance.
“Being able to provide early warnings of possible severe weather is all the more pertinent with climate change, as there is evidence that major winter storms will become more intense, exacerbating impacts such as flooding and wind damage.”
February 2022 was a particularly stormy month for the UK, Ireland, Scandinavia and Germany with several intense cyclones — rotating low-pressure weather systems that often create strong winds and heavy rain. A million homes were affected by power outages lasting up to several days. The estimated insurance bill for the UK and the rest of Europe owing to the windstorms was almost €4 billion.
Jeff Knight of the Met Office, a co-author of the study, said: “It’s been understood for a while that the Arctic stratosphere can affect the type of winter we get in the UK, but these results show that it can even affect the occurrence of stormy spells within the season.
“An intense stratospheric polar vortex can now be recognised as a warning to forecasters of increased risks of damaging storms. This was likely seen in the most recent winter, around the time of Storm Eowyn in late January.”
The results were published in the journal Communications Earth and Environment.
