Enhanced Moisture Uptake Drives Projected Increases in North Atlantic Tropical Cyclone Precipitation

Projected climate warming is expected to intensify tropical cyclone (TC) precipitation in the North Atlantic (NATL) basin; however, the associated changes in moisture sources remain unclear. Here, we apply a Lagrangian moisture-tracking framework to high-resolution FLEXPART-WRF simulations forced by a downscaled, bias-corrected CMIP6 dataset to quantify basin-wide and regional changes in moisture contributions under the SSP2-4.5 and SSP5-8.5 scenarios. We find a robust basin-wide increase of 9% to 20% in 6-hourly area-averaged TC-related moisture uptake, resulting in wetter storms with precipitation increases of 1.8% to 12.5% across all scenarios. While projections are consistent with the Clausius–Clapeyron scaling rate by mid-century, moisture uptake and precipitation exhibit smaller increases per degree of warming by the end of the 21st century, suggesting a complex, nonlinear relationship between TC-related precipitation and warming. The projected intensification is primarily driven by enhanced moisture supply from source regions near the TC, whereas more distant sources contribute less. Basin-wide shifts are accompanied by regionally amplified contributions from the Gulf of Mexico, the Caribbean Sea, and the western NATL, enhancing precipitation over the southeastern and eastern United States, respectively, particularly by the end of the century under SSP5-8.5. These results highlight the growing role of TCs in ocean-to-land moisture transport, with important implications for flood risk across the NATL basin under future warming.