Recent increases in U.S. heavy precipitation associated with tropical cyclones

Abstract

Precipitation time series for 935 long‐term U.S. climate stations were analyzed to identify daily extreme events associated with tropical cyclones (TCs). Extremes were defined as daily amounts exceeding a threshold for a 1 in 5‐yr occurrence. TCs account for 30% or more of all such extreme events at a number of stations and about 6% of the national annual total. During 1994–2008, the number of TC‐associated events was more than double the long‐term average while the total annual national number of events was about 25% above the long‐term (1895–2008) average. Despite the limited spatial area and portion of the annual cycle affected by TCs, the anomalous number of events associated with TCs accounted for over one‐third of the overall national anomaly for 1994–2008. While there has been a recent increase in the number of landfalling U.S. hurricances, the increase in TC‐associated heavy events is much higher than would be expected from the pre‐1994 association between the two.