26th Conference on Hurricanes and Tropical Meteorology

Wednesday, 5 May 2004
Seasonal prediction of Accumulated Cyclone Energy in the North Atlantic (Formerly Paper Number 11C.3)
Richelieu Room (Deauville Beach Resort)
Adam S. Lea, University College London, Dorking, Surrey, United Kingdom; and M. A. Saunders
Poster PDF (148.6 kB)
Seasonal forecasts of tropical storm activity in the North Atlantic and Northwest Pacific have focused on predicting the individual numbers of tropical storms/hurricanes/typhoons; these numbers being indicative of the overall seasonal activity. Recently NOAA introduced the Accumulated Cyclone Energy (ACE) index as a measure which is arguably more appropriate for representing the overall wind energy and thus activity of a season. This index reflects a combination of intensity and duration of all storms and is defined as the sum of the squares of 6-hourly maximum sustained wind speeds for all systems while they are at least tropical storm strength. We examine the seasonal predictability of the NOAA ACE index in the North Atlantic and Northwest Pacific at monthly leads out to 10 months from 1 August for the period 1950-2002 (Atlantic) and for the period 1970-2002 (Pacific). We show that there is skill to 95% confidence from early August in predicting the North Atlantic ACE index and from early May in predicting the Northwest Pacific ACE index.

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