The South Pacific and southeast Indian Ocean tropical cyclone season 1989-1990

There were sixteen tropical cyclones in the South Pacific and southeast Indian Ocean basin during the 1989-90 season. Six cyclones reached hurricane intensity and two of them, Ofa and Alex produced maximum winds exceeding 180 km h–1• Together, these two hurricanes caused damage costing US$180 million and 18 deaths, constituting close to 90 per cent of the total cyclone damage in the basin. Ofa seriously damaged the economies of Samoa and other nations in the South Pacific. The season's large-scale circulation features are discussed. Particular attention is given to the influence of the El Nino/Southern Oscillation (ENSO), the Walker circulation and the 40 to 60-day Julian-Madden oscillations on these large-scale features and tropical cyclone behaviour in the basin. The performance of the tropical cyclone warning system in the region is appraised and verification statistics are presented. There remains a major problem in monitoring tropical cyclones that track close to the GMS-4 satellite terminator. Finally, descriptions, track diagrams and life cycle details are provided for all the tropical cyclones in the basin.