A study shows that the contrast between wet and dry areas can increase rainfall by up to 30%.
Storm forecasting has traditionally relied on analyzing atmospheric conditions. However, groundbreaking research incorporating land surface factors, such as soil moisture, is poised to revolutionize early warning systems in tropical regions. This advancement could significantly improve communities’ ability to prepare for the destructive effects of climate change.
A new study led by the UK Centre for Ecology & Hydrology (UKCEH) found that large-scale contrasts in soil moisture, spanning hundreds of kilometers, can trigger atmospheric changes that enhance both the intensity and coverage of rainfall. In several global megastorm hotspots, this can lead to a 10–30% increase in rainfall, depending on the region and storm size.
The research focused on mesoscale convective systems, large, organized storm systems responsible for intense flash floods and mudslides across parts of Africa, Asia, the Americas, and Australia, affecting nearly four billion people worldwide.
These weather systems, which can be larger in size than England and travel hundreds of kilometers, bring intense storms that kill people and livestock, as well as destroying homes, infrastructure, and livelihoods.
Impacts of climate change
The study, by UKCEH, the University of Leeds (UK), and the Pacific Northwest National Laboratory (USA), has been published in Nature Geoscience.
Lead author Dr Emma Barton, a meteorologist at UKCEH, said: “Mesoscale convective systems are some of the most intense thunderstorms on the planet, and are increasing in severity due to climate change. Rising temperatures could increase the contrast between wet and dry areas of soils, further intensifying thunderstorms in already severely impacted regions.
“Understanding how soil moisture influences storm activity, and how this may change in the future, will be essential for more accurate short-term forecasting to warn communities about approaching storms, as well as making longer-term projections.”
Widespread damage
- Last year, Africa was reported to have had its worst storm season in several years. Between June and September, severe flooding in West and Central Africa, linked to heavy rainfall, killed a total of over 1,000 people, displaced more than 500,000, and destroyed over 300,000 homes.
- In Argentina in March 2025, a severe storm killed 13 people, displaced over 1,000, swept cars away, and destroyed roads and bridges.
- In Bengal, India, in March 2024, a thunderstorm damaged around 800 homes, injured 300 people, and killed five.
Improving warnings
The new study involved a detailed analysis of 20 years of satellite data relating to storm activity and soil moisture conditions in West Africa, southern Africa, India, and South America, as well as computer modeling.
The researchers found surface conditions that influence rainfall can be observed two to five days before a storm hits, which will allow advance warning of potential flash flooding.
Early warning allows people to move themselves, their families, livestock, vehicles, and possessions to upland areas, or to clear blocked drains in advance of storms to limit surface water flooding, for example.
The new study is part of ongoing UKCEH research funded by the Natural Environment Research Council (NERC). A previous study found land surface conditions often affect the direction and intensity of megastorms in the Sahel after they have formed, while a separate paper showed that deforestation increases the frequency of storms in some fast-growing African coastal cities.
Rethinking forecasting
“Meteorologists tend to focus on atmospheric conditions to predict weather patterns. But, as a growing amount of evidence shows, we should also consider what is happening on the land surface to improve forecasting,” said study co-author Dr Cornelia Klein, a meteorologist at UKCEH.
The study authors explain that greater contrast in moisture between wetter and drier areas over a large distance results in a greater contrast in air temperatures, leading to stronger shifts in wind direction and/or speed as you go higher up in the atmosphere. This turbulence helps storms grow, producing more rainfall over a larger area.
In addition to their analysis in West and southern Africa, India, and South America, the researchers observed the same connection between soil moisture contrasts and wind circulations in China, Australi,a and the US Great Plains. So while there were insufficient storm data to carry out a full analysis, they are confident that soil moisture contrasts are also exacerbating rainfall in other regions affected by mesoscale convective systems.
Developing accurate tools
The next step for the researchers is to explore what factors contribute to these regional variations. They are also using the latest, advanced climate models, which better incorporate storms, to improve understanding of the processes that make rainfall more intense as temperatures continue to rise under global warming.
Computer software tools being developed by UKCEH are enabling meteorological agencies to generate more reliable short-term forecasting (up to six hours ahead of storms) and therefore warnings to communities about approaching storms. These include an online ‘nowcasting’ portal based on satellite-derived data on atmospheric and soil conditions in Africa.
Reference: “Soil moisture gradients strengthen mesoscale convective systems by increasing wind shear” by Emma J. Barton, Cornelia Klein, Christopher M. Taylor, John Marsham, Douglas J. Parker, Ben Maybee, Zhe Feng and L. Ruby Leung, 4 April 2025, Nature Geoscience.
DOI: 10.1038/s41561-025-01666-8
The study was funded by the Natural Environment Research Council.
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