Dangerous thunderstorms: better models through soil-moisture data

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Thunderstorms don’t just appear out of thin air, say scientists
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The UK Centre for Ecology & Hydrology published yesterday the article you can read there, or here.

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.

There is no randomized way
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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
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The research, funded by the Natural Environment Research Council and the Met Office, both from UK, 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.”, he added

This has included the development of ‘nowcasting’ tools that provide warnings of storms up to six hours ahead.

Article from TU Wien
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Millions of thunderstorms have now been analysed, providing new insights into the development of extreme weather events. The key lies in the combination of soil moisture and wind.

A thunderstorm is forming. Thunderstorm cells tend to grow particularly rapidly and intensely where differences in soil moisture generate near-surface winds, while winds at higher altitudes blow in the opposite direction. Image credit & copyright: TU Wien

Thunderstorms are known to form preferentially on warm, humid days with unstable air, stated an article from Technische Universität Wien. But predicting where exactly a thunderstorm will develop has so far remained extremely difficult. Heavy rainfall often occurs very suddenly and locally – without warning, yet frequently with severe consequences.

A British-Austrian research team with the participation of TU Wien has now analysed 2.2 million thunderstorm events in Africa. In doing so, the researchers were able to identify a physical explanation for why thunderstorms form at certain locations while failing to develop elsewhere. It is the interplay between wind conditions in the atmosphere and spatial variations in soil moisture that determines whether a harmless cloud grows into a dangerous thunderstorm. The new physical model of thunderstorm development has now been published in the journal Nature.

Soil moisture as a driver of thunderstorms
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“Large-scale air-mass movements can be calculated very well today,” says Prof. Wolfgang Wagner from the Department of Geodesy and Geoinformation at TU Wien. “But thunderstorms form on intermediate spatial scales – on the order of a few kilometres. And this is precisely where current models reach their limits”, he said

For many years, TU Wien has been developing methods to derive soil-moisture information from satellite measurements on a global scale. Improvements in the spatial and temporal resolution of these satellite data have now made it possible to directly relate thunderstorm observations to soil-moisture patterns. This revealed a striking relationship:

Thunderstorm cells tend to grow particularly rapidly and intensely where differences in soil moisture generate near-surface winds, while winds at higher altitudes blow in the opposite direction.

If the soil in one region is wetter than in its surroundings, evaporation cools the near-surface air. Over drier areas, the air warms more strongly and surface pressure is lower. As a result, near-surface air flows from wetter towards drier regions. Wind directions several kilometres above the ground, however, are largely determined by large-scale weather systems and are mostly independent of local soil moisture.

It can therefore happen that clouds at higher altitudes move in exactly the opposite direction to the near-surface airflow. “When this occurs, the relative velocity is at its maximum,” explained Christopher Taylor (UK Centre for Ecology and Hydrology, UKCEH), lead scientist and principal author of the study. “The cloud comes into contact with the greatest possible amount of new, near-surface air per unit time – and this air then feeds the thunderstorm cell from below.”

Under these conditions, convection is strongest: moist air is drawn upward from below, cools as it rises, and can rapidly form large thunderstorm clouds. A self-reinforcing upward motion develops – a local instability turns into a thunderstorm. This sensitivity to small-scale conditions is precisely what makes thunderstorms so difficult to predict.

Millions of thunderstorms confirm the model
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The research team validated the model using independent data sets. Satellite imagery shows rapid cloud growth exactly where the model predicts it. Lightning observations confirm that the most intense thunderstorms preferentially form over relatively dry soil areas when near-surface winds and winds at higher altitudes are oppositely directed.

High-resolution satellite measurements of soil moisture were crucial for this analysis. These data were developed at TU Wien and provided by EUMETSAT, the European Organisation for the Exploitation of Meteorological Satellites. The study uses data from the European ASCAT instrument, which orbits the Earth aboard the Metop satellites operated by EUMETSAT. Using sophisticated, tailor-made physically based models, these measurements allow detailed estimates of local soil-moisture conditions.

The insights gained in this study are expected to enable more precise assessments of future thunderstorm development and to improve our understanding of the links between climate change and extreme weather events.

Citation
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The paper Wind shear enhances soil moisture influence on rapid thunderstorm growth was published in Nature journal. Authors: Christopher M. Taylor, Cornelia Klein, Emma J. Barton, Sebastian Hahn & Wolfgang Wagner

Taylor, C.M., Klein, C., Barton, E.J. et al. Wind shear enhances soil moisture influence on rapid thunderstorm growth. Nature 651, 116–121 (2026). https://doi.org/10.1038/s41586-025-10045-7

The article Thunderstorms don’t just appear out of thin air, say scientists was published in the UKCEH press website
You can read here Dangerous thunderstorms: better models through soil-moisture data the article from TU Wien

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