Increasing Flood Hazard Posed by Tropical Cyclone Rapid Intensification in a Changing Climate.

Tropical cyclones (TCs) that undergo rapid intensification (RI) before landfall are notoriously difficult to predict and have caused tremendous damage to coastal regions in the United States. Using downscaled synthetic TCs and physics‐based models for storm tide and rain, we investigate the hazards posed by TCs that rapidly intensify before landfall under both historical and future mid‐emissions climate scenarios. In the downscaled synthetic data, the percentage of TCs experiencing RI is estimated to rise across a significant portion of the North Atlantic basin. Notably, future climate warming causes large increases in the probability of RI within 24 hr of landfall. Also, our analysis shows that RI events induce notably higher rainfall hazard levels than non‐RI events with equivalent TC intensities. As a result, RI events dominate increases in 100‐year rainfall and storm tide levels under climate change for most of the US coastline. Plain Language Summary: Tropical cyclones (TCs) that rapidly intensify (RI) before hitting land are typically hard to predict and cause immense destruction. We used synthetic TCs downscaled from global climate models and physics‐based hazard models to examine the dangers posed by these RI storms in historical and future climates. The TC simulation shows that, as the climate warms, the number of TCs undergoing rapid intensification could rise substantially in the North Atlantic region. Additionally, the likelihood of rapid intensification within 24 hr of landfall significantly increases. These TCs are much riskier, particularly in terms of heavy rainfall, even when compared to equally strong TCs that did not rapidly intensify. Consequently, 100‐year rainfall and storm tide levels will greatly increase under climate change, largely due to the increase of RI events in the future. Key Points: Future climate warming causes large increases in the probability of rapid intensification (RI) within 24 hr of landfallRI events show notably higher rainfall hazard levels than non‐RI events even with equivalent TC intensityChanges in RI events dominate future increases in 100‐year rainfall and storm tide levels for most of the US coastline [ABSTRACT FROM AUTHOR]