Uncertainty Shapes Extreme Weather – New Study Reveals Hidden Risks in Europe’s Forecasts
Layered precipitable water imagery of particularly strong atmospheric rivers on 5 December 2015. The first, caused by Storm Desmond, stretched from the Caribbean to the United Kingdom; the second originated from the Philippines and crossing the Pacific Ocean extended to the west coast of North America. Image: NWS OPC - https://twitter.com/nwsopc, Public Domain, https://commons.wikimedia.org/w/index.php?curid=45444848
Atmospheric rivers are long, narrow corridors of moist air that can bring torrential rainfall, powerful winds, and sudden temperature shifts across Europe. But how well do we actually understand these weather giants? A new study in Scientific Reports, led by Venugopal Thandlam at Uppsala University, shows that the answer lies in something as unexpected as uncertainty.
Venugopal Thandlam, forskare i meteorologi.
The researchers reveal that current methods for mapping atmospheric rivers often produce very different results. This means that estimates of how often, where, and how intensely these phenomena strike can vary greatly – and so can our assessments of risks such as flooding, storm damage, and heatwaves.
"When our tools don’t agree on where and when atmospheric rivers occur, it becomes difficult to make reliable projections of their impacts," says Venugopal Thandlam.
By using a new AI-based method, TECA-BARD, the team was able for the first time to capture uncertainty in the very detection of these weather systems. The result? Inland Europe – from Germany to Scandinavia – turns out to be much more sensitive to how we define and detect atmospheric rivers than coastal regions.
This means that some of the most damaging extreme events risk being overlooked in today’s climate models. And with a changing climate, where atmospheric rivers are becoming stronger and affecting larger areas, misjudgments could have serious consequences for preparedness and planning.
"Uncertainty is not just a technical issue – it reshapes our understanding of extreme weather," says Thandlam.
The study underlines that future climate adaptation must account for multiple scenarios – not just a single best guess.
Read the study in Scientific Reports, a a journal within the Nature Portfolio:
Thandlam, V., Rutgersson, A., & Sahlée, E. (2025). Structural uncertainty in mapping Euro-Atlantic atmospheric rivers obscures understanding of associated meteorological extremes. Scientific Reports. https://doi.org/10.1038/s41598-025-19685-1