2017-18 South-West Indian Ocean cyclone season

The 2017-18 South-West Indian Ocean cyclone season was a hyperactive season, with 31 named storms and 23 tropical cyclones. It began on November 1, 2017 and ended on April 30, 2018, dates which conventionally delimit the year in which most tropical cyclones form in the basin. However any tropical cyclone that developed between July 1, 2017, and June 30, 2018 would have count towards the seasonal count. The South-West Indian Ocean basin is defined as being to the south of the equator and between the coast of Africa and 90°E. The basin is monitored by Meteo France in Réunion (MFR), while the Madagascan Weather Service (MWS) and Mauritius Meteorological Service (MMS) name tropical cyclones when they reach moderate tropical storm intensity. The Joint Typhoon Warning Center (JTWC) also issue warnings for the basin, designating tropical cyclones with a number and an "S" suffix.

Tropical Disturbance 01
A zone of disturbed weather (ZDW) was first mentioned in La Reunion's Tropical Weather Outlook (TWO) on October 3. They said that it would slowly strengthen into a tropical disturbance and then later a tropical depression. The ZDW then strengthened into a tropical disturbance on October 5, less than a month before the official start to the South-West Indian Ocean (SWIO) cyclone season. However, due to strengthening wind shear, the system was no longer forecast to become a tropical depression. The disturbance was stationary until October 14, when a system in the North Indian Ocean absorbed 01.

Tropical Depression 02
A tropical low formed north of Exmouth, Australia on October 24 where tropical cyclone watches had been issued. Those were immediately cancelled when the low was then forecast to move into the SWIO basin. Once the system had crossed 90&deg;E, the system was numbered 02 by the MFR and was classified as a tropical depression on October 31. The next day, the depression had turned to the south and started to encounter cooler sea surface temperatures (SST). However, the system maintained intensity until November 3 when it became an extratropical cyclone.

Intense Tropical Cyclone Abele
A ZDW formed east of Madagascar on November 12 and rapidly strengthened into a tropical depression and was numbered '03'. Hours later, the JTWC had issued a Tropical Cyclone Formation Alert (TCFA) on the system. During the morning hours of November 13, Tropical Depression 06 had strengthened into Moderate Tropical Storm Abele. The storm rapidly strengthened on November 15, when Abele became a tropical cyclone. Additional strengthening occurred during the night of November 15-16, when the cyclone became an intense tropical cyclone, with 10-min sustained winds of 105 mph. It began weakening due to cooler SSTs and higher wind shear. By November 18, the storm was just located south-west of Madagascar as a minimal moderate tropical storm. It rapidly weakened to a tropical disturbance on November 19 and dissipated. No watches or warnings were issued due to Abele.