1997–98 South-West Indian Ocean cyclone season

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1997–98 South-West Indian Ocean cyclone season — a concise overview

The 1997–98 season was unusually quiet and started late. The first tropical disturbance formed on January 16, 1998, and the first named storm, Anacelle, did not appear until February 8. The season’s last system dissipated on April 22, 1998, though there was an unusually late tropical depression noted into July in some records. Wind shear and a strong El Niño kept activity low, and only one storm reached tropical cyclone strength (a minimal hurricane equivalent).

Season at a glance
- First system formed: January 16, 1998
- Last system dissipated: April 22, 1998
- Strongest storm: Anacelle, with 140 km/h (85 mph) winds (10-minute average) and a pressure of 950 hPa
- Total disturbances: 16
- Total depressions: 8
- Total storms: 5 (official), 1 unofficial
- Tropical cyclones: 1
- Fatalities: around 88–144
- Total damage: unknown
- Causes: Active El Niño year and higher wind shear reduced storm development; ITCZ activity picked up in February, allowing some storms to form

Notable storms and impacts
- January: Tropical Depression A1 moved through Mozambique, bringing landslides and floods. In Milange District, many houses were washed into a river. The death toll in Mozambique was significant, with reports ranging roughly from 73 to over 140 lives lost and many people left homeless.
- February: Anacelle became the season’s strongest storm, reaching peak winds near 140 km/h (85 mph). It affected islands around the region, including Mauritius and Rodrigues, bringing strong winds and heavy rains. Earlier, a disturbance that would become Beltane spent time near Madagascar, causing heavy rainfall that led to crops losses and evacuations.
- February–March disturbances: Several other systems formed and moved through the region, bringing periods of heavy rainfall to Réunion and Mauritius, but most stayed weak and short-lived.
- March–April: A number of weaker storms and disturbances occurred, including activity that produced gusty winds and showers but did not develop into intense tropical cyclones. Gemma arose in early April and brought modest winds before weakening.

How the season was tracked
- The cyclone season was monitored by Météo-France Réunion (MFR), which serves as the Regional Specialized Meteorological Centre for the area. The U.S. Joint Typhoon Warning Center (JTWC) also issued warnings in an unofficial capacity.
- Naming and classification: A tropical disturbance is named when it reaches moderate tropical storm strength. Names are assigned by the Madagascar or Mauritius sub-regional centers, depending on where the system forms or tracks. A new annual names list is used each year, and no names were retired from this season.

Overall, the 1997–98 South-West Indian Ocean cyclone season stood out for its low activity, late start, and significant impacts mainly from rainfall-induced floods and landslides in Mozambique and Madagascar, despite only one storm reaching cyclone strength.