Climate researchers have identified an atmospheric configuration that can trigger intense flash flooding within minutes, according to a study led by the UK Met Office and Newcastle University.
Published in Weather and Climate Extremes, the research examines how certain atmospheric conditions can lead to severe rainfall. The findings may help improve risk identification and early warning systems. They provide new insight into some of the world’s most dangerous flash-flood events and could support efforts to mitigate their impacts.
The team found that the atmosphere can organize into a three-layered structure associated with the rapid development of very heavy rainfall. The study helps explain the record-breaking rainfall and flash flooding that affected the United Arab Emirates and Oman between April 14 and 16, 2024.
Researchers applied the Davies four-stage conceptual model for life-threatening rainfall extremes, which describes how severe rainfall develops through a sequence of processes: pre-conditioning, lifting, realization of moist absolutely unstable layers (MAULs), and the transition away from intense rainfall.
Using this framework, the team analyzed the April 2024 event and found that a rare combination of weather systems funneled large amounts of warm, moist air into the region. Although atmospheric instability was limited, deep saturation created conditions for intense and prolonged rainfall.
The analysis focused on MAULs – saturated atmospheric layers in which air rises rapidly because it is warmer than the surrounding air. Scientists identified a relationship between MAUL depth, saturation fraction and total rainfall. A deep MAUL combined with near-complete saturation was linked to heavier rainfall in the hours leading up to and during peak precipitation.
By considering MAUL depth and atmospheric saturation together, the researchers suggest forecasters could eventually distinguish between typical rainstorms and the intense downpours that lead to flash flooding. This could support improvements in early warning systems and climate resilience in vulnerable regions.
Prof. Paul Davies from Newcastle University School of Engineering and a former chief meteorologist at the Met Office, said, “We now have evidence that this phenomenon is responsible for these rainfall extremes. If we implement these processes in today’s weather models, and work with partners and communities to build solutions that mitigate against the consequences of extremes, then we believe our methods could give further advance notification to enable everyone to protect themselves and their livelihoods.”
Prof. Hayley Fowler, professor of climate change impacts at Newcastle University, added, “Our group is committed to implementing these new science advances into operational systems as soon as practicably possible. This improvement in early warnings of walls of water will help to save lives around the world as the frequency of these short-duration downpours is increasing rapidly in our warming climate.”
Dr David Flack, regional model evaluation scientist at the Met Office, said, “Having developed the conceptual model over the UK, its wider applicability is encouraging for the creation of a new globally applicable forecasting technique that complements existing ones to enhance warnings, thus allowing people to make the decisions that they need to stay safe and thrive both now and in a changing climate.”
The study builds on earlier work that showed how atmospheric saturation influences rainfall type and intensity. The findings may also help explain extreme rainfall events in other regions as global temperatures rise.
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