High Quality Content by WIKIPEDIA articles! The 1990–91 South-West Indian Ocean cyclone season was an average cyclone season, with ten tropical cyclones occurring within the region between 90°E and 160°E. The season officially ran from November 1, 1990, to April 30, 1991 however the first disturbance of the season formed on September 21 before the last disturbance dissipated during May 19. During the season, 7 named storms developed during the season and were monitored by the Reunion Meteorological Service. The United States Joint Typhoon Warning Center (JTWC) also monitored systems within the basin during the season and designated systems with a number and either an S suffix.