1992–93 South-West Indian Ocean cyclone season


The 1992–93 South-West Indian Ocean cyclone season lasted longer than normal, with the first storm Aviona forming on September 27 and the final storm Konita not dissipating until May 7. It was an above-average season, with four tropical cyclones – the equivalent of a minimal hurricane – along with six tropical storms, one subtropical depression, and several depressions including one that was named. The basin is defined as the area west of 90°E and south of the Equator in the Indian Ocean, which includes the waters around Madagascar westward to the east coast of Africa. Tropical cyclones in this basin are monitored by the Regional Specialised Meteorological Centre in Réunion, as well as by the Joint Typhoon Warning Center.
At the time, the season officially went from November 15, 1991, to April 30, 1992, although this season began in September with the formation of Tropical Storm Aviona in the northeastern portion of the basin. A month later, Tropical Storm Babie also formed in the northeastern portion of the basin before the season's official start. After several depressions formed in December and early January, Cyclone Colina formed and struck Réunion, which damaged houses and killed 2 people and left 12 missing there. Three storms were active at the same time in the middle of January, including Colina – Tropical Storm Dessilia moved across Madagascar with gusty winds, and Cyclone Edwina was the longest-lasting and strongest storm of the season. Edwina brushed the Mascarene Islands with gusty winds and light rainfall. In mid-February, Tropical Storm Finella brought locally heavy rainfall to Réunion, reaching along the island's east coast and causing minimal rainfall along the southern coast. The Intertropical Convergence Zone became active toward the end of February, spawning tropical storms Gracia and Ionia as well as Tropical Depression Hutelle. Ionia, the last of five system to cross Madagascar during the season, killed eight people in the country. The season ended with Cyclone Jourdanne, which was the second-strongest storm of the season in April, and Cyclone Konita in May.

Seasonal summary



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During the season, the Météo-France office on Réunion island issued warnings in tropical cyclones within the basin. The agency estimated intensity through the Dvorak technique, and warned on tropical cyclones in the region from the coast of Africa to 90° E, south of the equator. The Joint Typhoon Warning Center, which is a joint United States Navy – United States Air Force task force, also issued tropical cyclone warnings for the southwestern Indian Ocean. The storms in the season lasted about five days on average, although Cyclone Edwina lasted the longest at 11 days. Storms formed throughout the basin and were fairly evenly distributed throughout the season, with the exception of a lull in November. Most storms originated from the Intertropical Convergence Zone. MFR named storms throughout the season using 11 names from a sequential list. The remainder of the list was Laura, Monette, Neige, Octavie, Pamela, Rosita, Stella, Tasiana, Vigonia, Wendy, and Yolande.

Systems

Moderate Tropical Storm Aviona

On September 25, a low-pressure area persisted between the Cocos Islands and Sumatra in the Australian region, east of 90° E. It moved southwestward into the south-west Indian Ocean due to a large ridge to the south. The system slowly organized, becoming a tropical disturbance on September 27; on the same day, the JTWC also initiated advisories on the system as Tropical Cyclone 01S. This marked an unusual event of such an early storm formation. On September 29, the system was named Moderate Tropical Storm Aviona, although the MFR later assessed that the system reached tropical storm status on the previous day. In addition, the JTWC estimated the system attained 1-minute sustained peak winds of on September 28, the equivalent of a minimal hurricane. When Aviona was named, the MFR estimated peak 10-minute sustained winds of 75 km/h. Subsequently, increased wind shear incurred weakening due to a trough to the south, which stripped the convection from the center. A building ridge behind the trough turned Aviona to the west. The storm weakened to a depression on October 1, the same day the JTWC discontinued advisories. The circulation continued generally west-southwestward until dissipating on October 5 to the north of Rodrigues island.

Moderate Tropical Storm Babie

The ITCZ became active on October 17, spawning an area of disturbed weather about east of Diego Garcia in conjunction with a pre-existing low-pressure area. Convection quickly organized around a center, and a tropical disturbance formed on October 18. On the same day, the JTWC began issuing warnings on the system as Tropical Cyclone 02S. A trough to the south steered the system to the south-southwest. Following steady intensification, the disturbance became Tropical Storm Babie on October 19, reaching peak winds of. A building ridge to the south increased wind shear, causing Babie to quickly weaken; the JTWC and MFR discontinued advisories on October 21, and the circulation dissipated on October 23.

Tropical Depression C1

Tropical Depression C1 originated from the ITCZ in the northeastern portion of the basin from a small area of convection on November 24. It moved westward with pulsating convection around the center, failing to organize due to the presence of wind shear. On December 4, the system organized into a tropical disturbance, and three days later it passed about north of the northern tip of Madagascar. That day, it intensified to tropical depression status, reaching peak winds of. Increased wind shear weakened the convection, and the circulation dissipated on December 10.

Tropical Cyclone Colina

The ITCZ spawned an area of convection on January 11 near the Chagos Archipelago. A circulation developed within the system on January 13 about southwest of Diego Garcia, and at that time it became a tropical disturbance. A large ridge to the south steered the system generally to the southwest. The disturbance intensified into a depression on January 14, the same date that the JTWC initiated advisories on Tropical Cyclone 10S, and following an increase in convection, the depression intensified into Moderate Tropical Storm Colina on January 15. Turning more to the south-southwest, Colina strengthened further into a tropical cyclone on January 18, developing a eye. On the next day, the cyclone attained peak 10-minute winds of, according to MFR, while the JTWC estimated peak 1-minute winds of. That day, the eye crossed over the western portion of Réunion at around 14:30 UTC, exiting 45 minutes later. Subsequently, Colina accelerated to the southeast over cooler waters, weakening in the process. On January 20, the cyclone weakened to tropical storm status, and the next day Colina became extratropical, dissipating two days later.
Early in its duration, Colina dropped rainfall in Seychelles through the interaction with the ITCZ. The rains caused flooding and mudslides, and the storm also produced high waves and gusty winds. Moving across Réunion, Colina produced strong wind gusts in the mountainous peaks, reaching at La Plaine-des-Palmistes. The storm dropped rainfall across the entire island, peaking at at Mafate in a 24‑hour period. The winds and rainfall damaged crops and houses and also caused power outages. The storm killed two people on the island during its passage, with 12 others missing. On nearby Mauritius, Colina dropped about of rainfall and produced wind gusts of ; the storm did not cause much damage there.