Variations in the Intensity and Spatial Extent of Tropical Cyclone Precipitation

The intensity and spatial extent of tropical cyclone precipitation (TCP) often shapes the risk posed by landfalling storms. Here we provide a comprehensive climatology of landfalling TCP characteristics as a function of tropical cyclone strength, using daily precipitation station data and Atlantic US landfalling tropical cyclone tracks from 1900-2017. We analyze the intensity and spatial extent of ≥ 1 mm/day TCP (Z₁) and ≥ 50 mm/day TCP (Z₅₀) over land. We show that the highest median intensity and largest median spatial extent of Z₁ and Z₅₀ occur for major hurricanes that have weakened to tropical storms, indicating greater flood risk despite weaker wind speeds. We also find some signs of TCP change in recent decades. In particular, for major hurricanes that have weakened to tropical storms, Z₅₀ intensity has significantly increased, indicating possible increases in flood risk to coastal communities in more recent years.