An updated statistical scheme for forecasting seasonal tropical cyclone activity in the Atlantic basin by 1 December of the previous year is presented. Previous research by Gray and colleagues at Colorado State University showed that a statistical forecast issued on 1 December of the previous year could explain up to about 50 percent of the jackknife hindcast variance for the 1950-1990 time period. Predictors utilized in the original forecast scheme included a forward extrapolation of the Quasi-Biennial Oscillation (QBO) and two measures of West African rainfall. This forecast has been issued since 1991 but has shown little skill because of the as yet unexplained failure of the West African rainfall predictors during the 1990s.

The updated scheme presented in this paper does not utilize West African rainfall predictors. It employs the new NCEP/NCAR reanalysis data and involves predictors that span the globe. Much experimentation has led to the choosing of conditions associated with the El Nino-Southern Oscillation (ENSO), the Arctic Oscillation (AO), the North Atlantic Oscillation (NAO), the Pacific-North American Pattern (PNA) and the Quasi-Biennial Oscillation (QBO). This new statistical scheme shows similar cross-validated (jackknifed) hindcast skill (explaining greater than 50 percent of the variance) but is developed over a decade longer time period (1950-2001). In addition, since all predictors are taken directly from the NCEP/NCAR reanalysis, one does not need to consider rainfall collection issues which have caused major problems with the West African rainfall data since 1995. Hypothetical physical linkages between the predictors and the following year's hurricane activity are also presented. Based on the Net Tropical Cyclone (NTC) activity prediction and a weighted average of North Atlantic sea surface temperatures, forecasts of United States hurricane landfall probability can also be issued which showed considerable hindcast skill over the 52 year period of 1950-2001.