Dec 23, 2010

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

Kenneth E. Kunkel, David R. Easterling, David A.R. Kristovich, Byron Gleason, Leslie Stoecker, Rebecca Smith
Geophysical Research Letters
  • Analyzes precipitation time series for 935 long-term U.S. climate stations to identify daily extreme events associated with tropical cyclones (TCs)
  • Defines extremes as daily amounts exceeding a threshold for a 1 in 5-yr occurrence
  • Finds that TCs account for 30% or more of all such extreme events at a number of stations and about 6% of the national annual total
  • Finds that 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
  • Finds that 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
  • Regional results show there are positive heavy precipitation event index (HPEI) anomalies in all nine regions from 1994–2008, suggesting a multitude of meteorological causes for the overall national anomaly, with TCs making a substantial contribution in four regions:
    • Northeast (73% HPEI anomaly, 32% TC contribution),
    • Central (26%, 51%),
    • South (25%, 48%), and
    • Southeast (40%, 100%)
  • Finds that in the Northeast, Central, and South regions, factors other than TCs make at least an equal contribution to the recent anomalies; however, the Southeast anomaly is solely a result of anomalous TC contributions