The Role of Wind‐Moisture Characteristics in Shaping Atmospheric River Flood Hazards

Abstract Atmospheric rivers (ARs) are key drivers of extreme precipitation in the Western U.S. Using regionally downscaled thermodynamic global warming (TGW) simulations, we examine how ARs with varying wind and moisture characteristics respond to warming. We classified 812 historical AR events into Gusty‐Wet, Gusty‐Dry, Calm‐Wet, and Calm‐Dry groups to evaluate differences in precipitation behavior. ARs with stronger winds and higher moisture content exhibit higher precipitation efficiency (PE) and greater integrated water vapor (IWV). Regionally, Calm ARs show higher IWV accumulation due to slower inland transport and reduced PE. Projections indicate increases in storm‐total (sub‐Clausius‐Clapeyron (CC) scaling) and maximum 3‐hourly precipitation (super‐CC scaling) across all groups, with the most pronounced changes in Gusty‐Wet and Calm‐Wet ARs. Spatial differences in surface runoff, PE, and inland reach highlight the importance of AR subtype in shaping future flood hazards. These results offer insights into event‐level and regional‐scale precipitation changes under evolving environmental conditions.