February 2022: Wet, windy and wild
A spate of severe weather in February 2022 made the headlines across much of the UK and Northern Europe. Most notably, a trio of storms named Dudley, Eunice and Franklin by the Met Office – the UK’s national weather service – occurred within the space of a week. Storm Eunice holds the current record for the strongest wind gust observed in the UK (122 mph at the Needles on the Isle of Wight). The storm was accompanied by gusts of ~80 mph across London, resulting in the shredding of the roof of the landmark O2 Arena.
Damage to The O2 Arena's tent caused by Storm Eunice. Credit: Isochrone / Wikimedia Commons /
CC-BY-SA 4.0
The quick succession of these weather systems constituted a ‘storm clustering event’, in which the impacts from a combination of extreme wind gusts and heavy precipitation were compounded by the rapid succession of the consecutive storms. Insured losses were estimated to be around €3.8 bn.
A mighty polar vortex: How did it shape the weather?
The stratospheric polar vortex (SPV) is a band of strong westerly winds that circles the North Pole in winter between 10 and 50 km altitude. The SPV is known to impact Northern Hemisphere weather, particularly in late winter over the North Atlantic region. A strong SPV has been linked previously to an intensified jet stream lower down in the atmosphere, with implications for the North Atlantic storm track.
As atmospheric scientists, we could not help but notice the coincidence of an exceptionally strong SPV throughout the month of February 2022. To investigate this, we turned to sophisticated numerical models of the Earth’s climate system. A signal that the SPV would be stronger than usual was already evident in these models at the start of January 2022, despite the challenges of predicting atmospheric conditions 1- to 2-months in advance. Leveraging a large multi-model set of seasonal-length forecasts, therefore, we separated forecasts that showed the strongest and weakest SPV states. These subsets of forecasts revealed notable differences in North Atlantic weather conditions. Forecasts with a strong SPV showed more frequent intense North Atlantic storms and a greater likelihood of cyclone clusters, compared to the set with a weaker SPV state. However, this approach alone does not enable us to state categorically that the strong SPV contributed to the notably stormy month, since a common factor could have affected both the cyclones and the SPV in the forecasts.
To probe further, therefore, we performed idealised subseasonal forecast experiments with the Met Office and European Centre for Medium-Range Weather Forecasts (ECMWF) models. The SPV in these simulations was constrained to match either the observed strong state in February 2022, or a counterfactual state corresponding to an average SPV. With these experiments, we were able to isolate the influence of the SPV. The results were found to closely corroborate the signal derived from original subsets of seasonal forecasts.
Main findings
We demonstrate that the strong SPV during February 2022 significantly increased the likelihood that storms of the intensity observed would occur. We estimate that the deepest storm observed (Storm Franklin; in which the barometer dropped to as low as 954 mb near the UK) was made 1.5 to 3 times more likely by the strong SPV. The chance that three major storms (defined as those in which the central pressure fell below 970 hPa) would pass over the UK in a week, was enhanced by around 80%. Our study also highlights an increased probability of higher monthly precipitation totals and maximum wind gust speeds over the UK and Northern Europe. Even with a ~10-15 % increase in the most intense wind gusts, as our work suggests, there is a large increase in damage potential. Based on an index metric of storm severity, this equates to a 3 to 4-fold increase in wind gusts hazards, meaning a large payout on insured losses could have been anticipated.
A heads up for next time?
Our attribution study is the first to our knowledge in quantifying the role of a strong SPV on clusters of winter storms and their impacts. Applying our approach to other cases, such as February 2020, when the SPV was similarly strong and stormy conditions occurred, is required to understand how representative our findings are more widely. We also know that the weather in the North Atlantic sector has a wide range of influences, so it is not as simple as using the strength of the SPV as a direct forecast of storminess in North-West Europe. This winter (2024/25) is a prime example, as the SPV was again notably strong, yet weather conditions on the whole would not have been considered notably stormy over the UK and Northern Europe. However, a storm clustering event was observed in late January, which included disruptive storms Éowyn and Herminia.
Nevertheless, our study serves to highlight stratospheric ‘windows of opportunity’ in identifying the risks of storms, particularly given a strong SPV has a reasonable level of predictability several weeks in advance. This provides scope for early warnings of periods of impactful winter weather. The issue of climate change makes this even more pertinent, given robust indications that winter storms will likely be more intense in future.
Our research is published in Communications Earth & Environment.