Tropical cyclones are non-frontal, low-pressure systems that develop, within an environment of warm sea surface temperatures and little vertical wind shear aloft.[1] Within the South Pacific, names are assigned from a pre-determined list, to such systems, once they reach or exceed ten-minute sustained wind speeds of 65 km/h (40 mph), near the center, by either the Fiji Meteorological Service or New Zealand's MetService.[1] Within the South Pacific, tropical cyclones have been officially named since the 1964–65 South Pacific cyclone season, though a few meteorological papers show that a few tropical cyclones were named before 1964–65.[2][3][4] The names of significant tropical cyclones that have caused a high amount of damage and/or caused a significant number of deaths are retired from the lists of tropical cyclone names by the World Meteorological Organization's RA V Tropical Cyclone Committee at their bi-annual meeting.[1]
Within the South Pacific, there have been a total of 115 tropical cyclone names retired. The most intense tropical cyclone to have its name retired was Winston, which had an estimated peak pressure of 884 hPa (26.1 inHg). The deadliest tropical cyclone to have its name retired was Severe Tropical Cyclone Namu, which caused over 100 deaths, when it affected the Solomon Islands in May 1986. The most damaging system was Yasi which caused over US$2.5 billion in damage to Vanuatu, the Solomon Islands, and Australia in January and February 2011.