People may be frustrated by the lack of detail when weather forecasters say "there will be thunderstorms popping up, but we don't know where". Now a key finding in a study by the UK Centre for Ecology & Hydrology (UKCEH), published in the journal Nature, is set to improve the certainty about the location of upcoming storms on hot days.
Climate change is bringing more intense rainfall, and improving forecasting and warnings to communities globally will save the lives of people and livestock as well as better protect property and infrastructure. Thunderstorms caused around 30,000 deaths and $500 billion in economic losses between 2010 and 2019, according to the World Meteorological Organization .
Storms can develop on hot afternoons within less than 30 minutes of clouds starting to build up, providing little time for people to take evasive action. But the new UKCEH-led study found interactions between soil moisture patterns and wind in the lowest few kilometres of the atmosphere influence where storms develop – so monitoring these patterns would provide earlier warnings.
The research focused on sub-Saharan Africa where there are regularly intense thunderstorms, and there is an urgent need to improve knowledge and forecasting where flash-flooding has a big impact on large urban populations.
The researchers studied satellite images of the atmospheric conditions leading up to 2.2 million storms spanning 21 years (2004-2024). They believe the principle they have identified will be applicable to the birth of thunderstorms in other parts of the world – not only in the worst-hit tropical regions in Africa, Asia, the Americas and Australia, but also Europe.
Trigger is not random
Lead author Professor Christopher Taylor, a meteorologist at UKCEH, said: "Thunderstorms can sometimes suddenly appear, seemingly 'out of thin air'. But our research has shown that where they are triggered is more predictable than was previously thought.
"The findings will support our continuing work with national meteorological agencies to develop more accurate, AI-based forecasting systems to improve local predictions of downpours and lightning, particularly in parts of the world that experience the most intense thunderstorms."
Professor Taylor explained the study brought together ingredients of thunderstorm development that had previously been treated separately. It is well known that how winds vary with height – known as shear – affects storm severity, and also that high temperatures from parched soils located close to cooler, wetter ground favours the growth of storm clouds.
The study found that clouds are most likely to grow rapidly where soil moisture patterns align with wind shear, providing clues to forecasters about where thunderstorms will develop later in the day. However, the researchers must firstly translate this new knowledge – aided by AI – into better models for predicting storms' location.
Guiding improvements
The research, funded by the Natural Environment Research Council and the Met Office, found there were 68% more explosive storms given favourable soil moisture patterns. The study was made possible by an innovation by TU Wien that enabled scientists to obtain high-resolution data from satellite images, in order to reveal finer-scale details of soil wetness every day.
Dr Cheikh Abdoulahat Diop of ANACIM, the national meteorological agency in Senegal, said: "This latest study can guide improvements to early warning systems for flash flooding, lightning hazards and severe wind, which will be especially beneficial for affected regions that have high populations but limited weather radar coverage.
"Ongoing research by UKCEH and partners is improving scientific understanding of land-atmosphere interactions, and is already delivering major benefits for forecasting and risk planning across West Africa."
This has included the development of 'nowcasting' tools that provide warnings of storms up to six hours ahead.
