Abstract
Atmospheric rivers are narrow bands of water vapor transport and serve as key drivers of water supplies and flood hazards in mid-latitude regions. The atmospheric river scale supports early-warning communication by ranking events from potentially beneficial to hazardous based on atmospheric forcing represented by water vapor transport magnitude and duration. However, the scale does not consider land-surface conditions that can influence how precipitation derived from water vapor translates into streamflow and flood hazards. Analyzing atmospheric river landfalls across catchments in California and central Chile, we show that divergences between atmospheric river rank and flood response are primarily explained by pre-existing soil moisture conditions. Based on this insight, we develop a simple modification to the atmospheric river scale that nearly doubles the scale’s correspondence with peak streamflow and increases the number of flood-generating atmospheric rivers classified as hazardous by more than 30%. These findings demonstrate that incorporating land-surface conditions can enhance early-warning hazard classification tools.
Data availability
All source data used in this study are publicly available and accessible from the sources described in the Methods and Supplementary Methods. The data generated in this study are available in a CUAHSI HydroShare repository (https://doi.org/10.4211/hs.cee30237618d48e8bb0d09ecff9a4a7c)71.
Code availability
Statistical analyses were conducted in the R programming language. The code used to conduct these analyses is available in a CUAHSI HydroShare repository (https://doi.org/10.4211/hs.cee30237618d48e8bb0d09ecff9a4a7c)71.
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Acknowledgements
This material is based upon work supported by the National Science Foundation (NSF) through the Graduate Research Fellowship Program (Grant No. 1937966, M.J.W.) and the International Research Experience for Students (IRES) program (Grant No. 1954140, M.J.W.). Additional funding for M.J.W. was provided by the Desert Research Institute (DRI) Maki Student Award. Funding for C.M.A. and G.Y. was provided by the USACE Engineer Research and Development Center Urban Flood Demonstration Program (Agreement No. W912HZ1920011).
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M.J.W., C.M.A., D.B., and R.D.G. conceptualized the study and designed the methodology. M.J.W. performed the data acquisition and formal analysis with support from A.M.W., C.M.A., D.B., G.Y., and R.D.G. M.J.W. wrote the original draft. A.M.W., C.M.A., D.B., F.M.R., G.Y., M.J.W., M.L.A., and R.D.G. contributed to the review and editing of the manuscript. C.M.A. and M.J.W. acquired funding for this research.
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Webb, M.J., Albano, C.M., Bozkurt, D. et al. Antecedent moisture enhances early warning of atmospheric river flood hazards. Nat Commun (2026). https://doi.org/10.1038/s41467-026-69286-3
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DOI: https://doi.org/10.1038/s41467-026-69286-3