SEASONAL FORECASTS OF TROPICAL CYCLONE ACTIVITY OVER THE WESTERN NORTH PACIFIC:A REVIEW

The attempt of this article is to provide a literature review on recent development and progress in seasonal forecasts for tropical cyclone(TC) activity over the western North Pacific(WNP). Since the predictability of seasonal TC activity mainly comes from the slowly-evolving sea surface temperature(SST) conditions and the large-scale atmospheric circulation teleconnection patterns, our current understanding on the relationships between the interannual TC variability and tropical SST forcing and variations of various climate modes is first reviewed. It serves as the scientific basis and gives us ideas how predictable the seasonal TC activity is. The main body of the article focuses on an overview of the forecast approaches and methodologies, including statistical and dynamical models and their combination, currently used in seasonal forecasts for TCs over the WNP, and an initial assessment of their prediction skills in the past decade or so. Some outstanding issues, including the intrinsic limitation of predictability due to various uncertainties and the areas for future developments, are also briefly discussed. It is expected that the quality of the scientifically based seasonal TC forecasts would be steadily improved with the advancement in the forecast techniques and the driving of society needs.