Future Changes in Atlantic Tropical Cyclone Precipitation and Size in Convection-Permitting Regional Model Simulations

Tropical cyclone (TC) precipitation is projected to increase in the future, although the magnitude and whether its scaling with temperature will exceed the theoretical Clausius-Clapeyron (CC) rate remains uncertain. In this study, we investigated future changes in TC precipitation and its scaling with temperature in 10 TC events that impacted the United States and Caribbean Islands. We performed four-member ensembles of convection-permitting regional model simulations for each TC under historical conditions and under a high-emissions scenario for the mid-21st century. We found that future TC precipitation in a reference frame following the TC increased up to ∼1.5 times the historical for all 10 TCs and scaled at super-CC rates of 9%–17% K⁻¹ for nine of the 10 TCs. Precipitable water scaling was less than precipitation scaling for nine of 10 TCs, indicating that it alone did not fully explain the future TC precipitation changes. Midtropospheric ascent increased in the future by 8%–30% for nine of the 10 TCs and supported the super-CC precipitation increases. For TC size, we found that the radius of maximum wind during peak TC intensity decreased for nine of 10 TCs by up to 40%; however, the correlation with precipitation scaling was weak and insignificant. In addition, we found that thermodynamically driven TC translation speed exhibited no systematic future change and poorly explained regional storm-total precipitation changes. This study indicates that TCs can enhance future flooding risk regardless of changes in TC size or translation speed, with precipitation increases that exceed simple theoretical thermodynamic estimates.