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 Australian region, names are assigned from three pre-determined lists, 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 Australian Bureau of Meteorology, Papua New Guinea's National Weather Service or Indonesia's Badan Meteorologi Klimatologi dan Geofisika.
Among the retired storms are cyclones Gwenda and Inigo, two of the most intense systems ever recorded in the Southern Hemisphere; both attained a barometric pressure of 900 hPa (26.58 inHg).
[5] After the new Australian government had failed to create a federal weather bureau and appoint him director, Wragge started naming cyclones after political figures.
[5][7] The practice of retiring significant names was started during 1955 by the United States Weather Bureau in the Northern Atlantic basin, after hurricanes Carol, Edna, and Hazel struck the Northeastern United States and caused a significant amount of damage in the previous year.