Study Highlights Growing Importance Of Multi-Day Storms In Future U.S. Flood Risk
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https://news.okstate.edu/articles/engineering-architecture-technology/2026/study- highlights-growing-importance-of-multi-day-storms-in-future-u.s.-flood-risk <-- shared technical article
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https://doi.org/10.1088/2752-5295/ae4f14 <-- shared paper
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H/T @Mischelle Parsnik
“Researchers… have discovered that future flood risks may be influenced not only by intense downpours but also by prolonged storms lasting several days. The study projects that rare multi-day rainfall events could intensify in certain regions, heightening the potential for widespread flooding as water accumulates over time. These findings underscore the importance of flood planning and infrastructure that considers both rainfall intensity and storm duration…”
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“[Whilst] extreme rainfall is projected to intensify across the United States, some of the largest increases may come from storms that last several days rather than from short, intense downpours. The study [link above] analysed projections from 34 downscaled climate models to evaluate how extreme rainfall may change across 10 regions of the contiguous U.S. under different future emissions scenarios… The research examined both daily and multi-day rainfall extremes across a range of return periods, including rare events such as 100-year and 500-year storms. By using a large ensemble of climate models, the team was able to identify consistent trends while reducing the uncertainty associated with relying on a single model…”
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“Extreme rainfall is projected to intensify as the climate warms, yet whether the greatest increases will occur in multi-day or single-day events remains uncertain. This knowledge gap is particularly pressing given recent catastrophic floods triggered by multi-day rainfall events, prompting the question of whether multi-day events could, in fact, intensify more than their daily counterparts, and by how much. This study addresses this question using an ensemble of 34 downscaled Earth System Models under two Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5), focusing on changes in extreme rainfall by the end of the century across ten regions of the contiguous United States. [Their] statistical framework evaluates model agreement, ensemble-mean changes, and the significance of these changes for both daily and multi-day rainfall extremes. Results show that extreme rainfall amounts are expected to increase for most regions and durations. The degree of intensification, however, depends strongly on event rarity and regional climate characteristics. Notably, in the U.S. western Gulf Coast region, very rare multi-day events (e.g., 500 year return period) are projected to intensify more than their daily counterparts, a phenomenon that could be explained by increased stalling of tropical cyclones, which can prolong heavy rainfall over multiple days. These results challenge the assumption that daily extremes dominate future risk and highlight the need to consider event duration when updating flood-hazard maps, design standards, and adaptation planning…” #Flooding #FloodRisk #FloodInsurance #FloodAwareness #Explore #FloodPreparedness #FlashFlooding #ClimateResilience #climatechange #extremeweather #DisasterPreparedness #StormwaterManagement #FloodSafety #CommunityResilience #risk #hazard #model #modeling #floodrisk #multiday #rainfall #precipitation #storm #water #hydrology #hydrography #planning #policy #regulations #climatemodel #CONUS #USA #publicsafety #cost #economics #damage #loss #infrastructure #spatiotemporal #spatialanalysis #earthsystemmodels #forecasting #meteorology #designstandards #floodmapping #mitigation #flood