Intense Tropical Cyclone Felleng was a powerful

tropical cyclone A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Dep ...

that caused destruction across

Seychelles Seychelles (, ; ), officially the Republic of Seychelles (french: link=no, République des Seychelles; Creole: ''La Repiblik Sesel''), is an archipelagic state consisting of 115 islands in the Indian Ocean. Its capital and largest city, ...

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

, and

Réunion Réunion (; french: La Réunion, ; previously ''Île Bourbon''; rcf, label= Reunionese Creole, La Rényon) is an island in the Indian Ocean that is an overseas department and region of France. It is located approximately east of the island ...

. The seventh Tropical Disturbance, sixth named storm, and the third Intense Tropical Cyclone of the 2012–13 South-West Indian Ocean cyclone season, Felleng originated from an area of

atmospheric convection Atmospheric convection is the result of a parcel-environment instability, or temperature difference layer in the atmosphere. Different lapse rates within dry and moist air masses lead to instability. Mixing of air during the day which expands the ...

embedded in the Intertropical Convergence Zone. In total, Felleng caused 18 fatalities and above

US$ The United States dollar (symbol: $; code: USD; also abbreviated US$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official ...

10 million in damages.

Meteorological history

After the

Madden–Julian oscillation The Madden–Julian oscillation (MJO) is the largest element of the intraseasonal (30- to 90-day) variability in the tropical atmosphere. It was discovered in 1971 by Roland Madden and Paul Julian of the American National Center for Atmospheric ...

left its suppressive phase in the South-West Indian Ocean, a

low-pressure area In meteorology, a low-pressure area, low area or low is a region where the atmospheric pressure is lower than that of surrounding locations. Low-pressure areas are commonly associated with inclement weather (such as cloudy, windy, with possibl ...

embedded in the Intertropical Convergence Zone was noted by

Météo-France Météo-France is the France, French national Meteorology, meteorological service. Organisation The organisation was established by decree in June 1993 and is a department of the Ministry of Transportation. It is headquartered in Paris but man ...

La Réunion (MFR) on 24 January.

Convection Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the c ...

was mainly active in the northeast portion of the system, with winds reaching in some places. The system's low-level circulation was poorly defined by 25 January, with the system as a whole being negatively affected by

wind shear Wind shear (or windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizon ...

. At 18:00

Coordinated Universal Time Coordinated Universal Time or UTC is the primary time standard by which the world regulates clocks and time. It is within about one second of mean solar time (such as UT1) at 0° longitude (at the IERS Reference Meridian as the currently ...

(UTC), MFR upgraded the system to ''Tropical Disturbance 7'', with the

Joint Typhoon Warning Center The Joint typhoon Warning Center (JTWC) is a joint United States Navy – United States Air Force command in Pearl Harbor, Hawaii. The JTWC is responsible for the issuing of tropical cyclone warnings in the North-West Pacific Ocean, South P ...

(JTWC) upgrading it to a tropical depression at the same time, assigning it the designation ''13S''. A small

central dense overcast The central dense overcast, or CDO, of a tropical cyclone or strong subtropical cyclone is the large central area of thunderstorms surrounding its circulation center, caused by the formation of its eyewall. It can be round, angular, oval, or i ...

formed as

gale A gale is a strong wind; the word is typically used as a descriptor in nautical contexts. The U.S. National Weather Service defines a gale as sustained surface winds moving at a speed of between 34 and 47 knots (, or ).eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

, with a deep, intense ring of convective banding forming in the eyewall. On 31 January the eye became less well defined, and started to collapse. On 1 February the system started to become elongated, and weakened into a severe tropical storm as it began its extratropical transition. By 3 February, Felleng became fully extratropical, with the low level circulation center becoming totally exposed and elongated, under vertical wind shear, located to the west of the remnant convection.

Impact

Seychelles

Cyclone Felleng devastated the islands of Mahe, Praslin, and La Digue as a depression, many types of buildings were damaged and many farms were wiped out. Around 1,000 families were affected by floods and landslides, 246 of them were registered as displaced after their homes were damaged or destroyed. Damages from Felleng reached

8.4 million in the country.

Madagascar

Cyclone Felleng brought heavy rain to

, due to which floodwaters rose rapidly in the capital

Antananarivo Antananarivo ( French: ''Tananarive'', ), also known by its colonial shorthand form Tana, is the capital and largest city of Madagascar. The administrative area of the city, known as Antananarivo-Renivohitra ("Antananarivo-Mother Hill" or "An ...

, flooding many low-lying homes, as well as several hundred hectares of rice fields. Government authorities confirmed at least 800 people have been affected by the floods in the capital. Across the island, 9 people were killed and 1,303 were left homeless. A total of 162 homes were destroyed while another 1,803 were damaged by floodwaters, most of which were in

Vatovavy-Fitovinany Fitovinany is a region located in southeast Madagascar. Its capital is Manakara. It is inhabited by the Antemoro people. It formerly belonged to the region Vatovavy-Fitovinany that was split on 16 June 2021 to become the regions Vatovavy and Fit ...

Réunion

Cyclone Felleng's heavy rain and strong winds caused damage in Réunion Island, where 11,200 homes were left without power. Over the course of 72-hours, up to of rain fell in parts of the island, resulting in significant flooding. In

Plaine des Cafres The Plaine des Cafres is a plateau on Réunion Island, one of the French volcanic islands in the Mascarene Archipelago in the southwestern Indian Ocean. It is part of the commune of Le Tampon. It is named after the Cafres, black slaves who hi ...

, fell within 24‑hours.

References