2023–24 South-West Indian Ocean Cyclone Season
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The 2023–24 South-West Indian Ocean cyclone season was an above-average season, including ten named storms (including an unnamed tropical storm), six tropical cyclones and two intense tropical cyclones. Despite its moderate activity, it was the least deadly season in four years, causing only 53 deaths, most of which were caused by cyclones Alvaro and Gamane. It began on 15 November 2023, and ended on 30 April 2024, with the exception for
Mauritius Mauritius, officially the Republic of Mauritius, is an island country in the Indian Ocean, about off the southeastern coast of East Africa, east of Madagascar. It includes the main island (also called Mauritius), as well as Rodrigues, Ag ...
and the
Seychelles Seychelles (, ; ), officially the Republic of Seychelles (; Seychellois Creole: ), is an island country and archipelagic state consisting of 155 islands (as per the Constitution) in the Indian Ocean. Its capital and largest city, Victoria, ...
, where it ended on 15 May 2024. These dates conventionally delimit the period of each year when most tropical and subtropical cyclones form in the basin, which is west of 90°E and south of the
Equator The equator is the circle of latitude that divides Earth into the Northern Hemisphere, Northern and Southern Hemisphere, Southern Hemispheres of Earth, hemispheres. It is an imaginary line located at 0 degrees latitude, about in circumferen ...
. However, tropical cyclones can form year-round, and all tropical cyclones that formed between 1 July 2023 and 30 June 2024 would be part of the season. Tropical and subtropical cyclones in this basin are monitored by the
Regional Specialised Meteorological Centre A Regional Specialized Meteorological Centre (RSMC) is responsible for the distribution of information, advisories, and warnings regarding the specific program they have a part of, agreed by consensus at the World Meteorological Organization as ...
in
Réunion Réunion (; ; ; known as before 1848) is an island in the Indian Ocean that is an overseas departments and regions of France, overseas department and region of France. Part of the Mascarene Islands, it is located approximately east of the isl ...
and unofficially by 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 ...
. __TOC__


Seasonal forecasts

In October 2023,
Météo-France Météo-France is the official French meteorological administration, also offering services to Andorra and Monaco. It has the powers of the state and can exercise them in relation to meteorology. Météo-France is in charge of observing, study ...
issued its seasonal forecast of cyclone activity for the basin, predicting a below-average season with 5–8 moderate tropical storms due to an expected strong
El Niño EL, El or el may refer to: Arts and entertainment Fictional entities * El, a character from the manga series ''Shugo Chara!'' by Peach-Pit * Eleven (''Stranger Things'') (El), a fictional character in the TV series ''Stranger Things'' * El, fami ...
event. The MFR also stated that the chance for a below-average season was 70%. Average cyclone activity was given a 20% chance, while an above-average level of activity was given a 10% chance. The Mauritius Meteorological Services (MMS) also released their summer outlooks for the season, stating that around six to eight cyclones were expected to form, with the region west of
Diego Garcia Diego Garcia is the largest island of the Chagos Archipelago. It has been used as a joint UK–U.S. military base since the 1970s, following the expulsion of the Chagossians by the UK government. The Chagos Islands are set to become a former B ...
having environmental conditions more conducive for cyclogenesis.


Seasonal summary

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scales Scale or scales may refer to: Mathematics * Scale (descriptive set theory), an object defined on a set of points * Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original * Scale factor, a number ...
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The ACE index for the 2023–24 South-West Indian Ocean cyclone season as calculated by Colorado State University was 106.7 units. Through 2024, five tropical cyclones, four of which became tropical storms, formed outside the cyclone season in the southwest Indian Ocean, tying
2003 2003 was designated by the United Nations as the International Year of Fresh water, Freshwater. In 2003, a Multi-National Force – Iraq, United States-led coalition 2003 invasion of Iraq, invaded Iraq, starting the Iraq War. Demographic ...
with four named storms.


Season starts

The season officially started on 15 November 2023, however the first system, Alvaro, would not form until 30 December. Alvaro became a tropical depression the next day, traversing the Mozambique Channel, before making landfall in Morombe District,
Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...
on 1 January 2024. After a brief lull in activity, Tropical Cyclone Belal formed on 11 January. Belal would affect Mauritius and Reunion, killing six people. On 22 January, Moderate Tropical Storm Candice formed. On 25 January, Intense Tropical Cyclone Anggrek entered the basin, while Tropical Depression 05 emerging northeast of St. Brandon. After a lull period of about 3 weeks, the strongest storm being Intense Tropical Cyclone Djoungou from 13 February and exited the basin 6 days later. 17 February was the day Severe Tropical Storm Eleanor brought intense rainfall and winds which left at least 2 people injured, 10,000 customers deprived of electricity, several electricity pylons damaged, and toppled trees blocking several roads. It is the northern regions which suffered the greatest damage. Severe Tropical Storm Filipo emerged on 2 March near
Mozambique Mozambique, officially the Republic of Mozambique, is a country located in Southeast Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west, and Eswatini and South Afr ...
affecting 48,000 people and damaging 8,000 houses. Tropical Depression Neville crossed into the basin on 24 March but MFR discontinued warning issuance. Short-lived Tropical Cyclone Gamane emerged on 25 March north-northeast of Toamasina, Madagascar, causing a total of 19 deaths, 3 people missing and at least 90,000 affected.


Off-season

The season ended with 1 tropical cyclone each in April and May. At the very end of April, Tropical Cyclone Hidaya formed near
Seychelles Seychelles (, ; ), officially the Republic of Seychelles (; Seychellois Creole: ), is an island country and archipelagic state consisting of 155 islands (as per the Constitution) in the Indian Ocean. Its capital and largest city, Victoria, ...
and was the third tropical cyclone or depression in recorded history to make landfall in Tanzania, the others being an unnamed cyclone in 1952 and Tropical Depression Atang in 2002. Then on 16 May Tropical Cyclone Ialy formed east-northeast of
Comoros The Comoros, officially the Union of the Comoros, is an archipelagic country made up of three islands in Southeastern Africa, located at the northern end of the Mozambique Channel in the Indian Ocean. Its capital and largest city is Moroni, ...
, killing 2 people; strong winds tore off the roof of a school, killing a girl and injuring four others, while another person died due to a fallen wall.


Systems


Tropical Cyclone Alvaro

In December 2023, the MFR began to monitor the potential for
tropical cyclogenesis Tropical cyclogenesis is the development and strengthening of a tropical cyclone in the atmosphere. The mechanisms through which tropics, tropical cyclogenesis occur are distinctly different from those through which temperate cyclogenesis occu ...
as
Kelvin wave A Kelvin wave is a wave in the ocean, a large lake or the atmosphere that balances the Earth's Coriolis force against a topographic boundary such as a coastline, or a waveguide such as the equator. A feature of a Kelvin wave is that it is non-d ...
s and
Rossby wave Rossby waves, also known as planetary waves, are a type of inertial wave naturally occurring in rotating fluids. They were first identified by Sweden-born American meteorologist Carl-Gustaf Arvid Rossby in the Earth's atmosphere in 1939. They ...
s intersected in the western portion of the agency's area of responsibility, ahead of a wet phase of the Madden–Julian oscillation (MJO). By 29 December, a
monsoon trough The monsoon trough is a convergence zone between the wind patterns of the southern and northern hemispheres. It is a portion of the Intertropical Convergence Zone in the Western Pacific,Bin WangThe Asian Monsoon.Retrieved 2008-05-03. and is dep ...
had produced
convection Convection is single or Multiphase flow, multiphase fluid flow that occurs Spontaneous process, spontaneously through the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoy ...
southeast of
Beira, Mozambique Beira () is the capital and largest List of cities in Mozambique, city of Sofala Province, in the central region of Mozambique. Beira is where the Pungwe River meets the Indian Ocean. It is the fourth-largest city by population in Mozambique, af ...
that spun, as convergence of winds increased within the system's closed surface circulation. The next day, the MFR classified the system as a tropical disturbance. Tracking southeast under the influence of a
ridge A ridge is a long, narrow, elevated geomorphologic landform, structural feature, or a combination of both separated from the surrounding terrain by steep sides. The sides of a ridge slope away from a narrow top, the crest or ridgecrest, wi ...
, the disturbance was further upgraded to a tropical depression by the MFR on 31 December. The warm core consolidated, causing the system to intensify into a moderate tropical storm and receive the name ''Alvaro'', with JTWC designated as ''Tropical Cyclone 04S''. During 1 January 2024, Alvaro's maintenance of a curved
band Band or BAND may refer to: Places *Bánd, a village in Hungary * Band, Iran, a village in Urmia County, West Azerbaijan Province, Iran * Band, Mureș, a commune in Romania * Band-e Majid Khan, a village in Bukan County, West Azerbaijan Province, ...
and the emergence of an
eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...
prompted the MFR to upgrade the system to a severe tropical storm, as Alvaro continued to strengthen under favorable conditions despite vertical
wind shear Wind shear (; also written 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 ...
in the mid-level
troposphere The troposphere is the lowest layer of the atmosphere of Earth. It contains 80% of the total mass of the Atmosphere, planetary atmosphere and 99% of the total mass of water vapor and aerosols, and is where most weather phenomena occur. From the ...
. Alvaro later made
landfall Landfall is the event of a storm moving over land after being over water. More broadly, and in relation to human travel, it refers to 'the first land that is reached or seen at the end of a journey across the sea or through the air, or the fact ...
in Morombe District, Madagascar, bringing sustained winds of and gusts of . Alvaro rapidly weakened due to the mountainous terrain of the island nation, with rainbands around the core no longer present. Alvaro re-entered the Indian Ocean on 3 January, re-intensifying back into a moderate tropical storm. By 18:00 UTC, the MFR classified Alvaro as a post-tropical depression after the storm had lost its tropical characteristics. The MFR issued its final bulletin on Alvaro on 4 January, as the system interacted with the baroclinic zone.


Tropical Cyclone Belal

On 11 January, the MFR marked a zone of disturbed weather, citing the conducive conditions induced by the MJO and an equatorial Rossby wave. The monsoon trough north-northeast of Madagascar had intensified several days prior, as convergence transferred moisture aloft. Concentration of convection near the center increased, particularly in the western section, as the system moved south. By the next day, the JTWC issued a
Tropical Cyclone Formation Alert A Tropical Cyclone Formation Alert (TCFA) is a bulletin released by the U.S. Navy-operated Joint Typhoon Warning Center in Honolulu, Hawaii or the Fleet Weather Center in Norfolk, Virginia, warning of the possibility of a tropical cyclone formi ...
(TCFA) on the potential disturbance, since it was in an environment of very warm
sea surface temperature Sea surface temperature (or ocean surface temperature) is the ocean temperature, temperature of ocean water close to the surface. The exact meaning of ''surface'' varies in the literature and in practice. It is usually between and below the sea ...
s, high
ocean heat content Ocean heat content (OHC) or ocean heat uptake (OHU) is the energy absorbed and stored by oceans, and is thus an important indicator of global warming. Ocean heat content is calculated by measuring ocean temperature at many different locations and ...
, low vertical shear, and excellent outflow. At 12:00 UTC, the MFR categorized the system as a tropical depression. Additionally,
microwave Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Its wavelength ranges from about one meter to one millimeter, corresponding to frequency, frequencies between 300&n ...
imagery indicated an eye in the lower-layer while the storm steered more westward, and the JTWC began issuing advisories on the system as a tropical cyclone. By 13 January, it intensified to a moderate tropical storm, prompting the MMS to name it ''Belal''. Intense lightning activity within the center further signaled a period of
rapid intensification Rapid intensification (RI) is any process wherein a tropical cyclone strengthens very dramatically in a short period of time. Tropical cyclone forecasting agencies utilize differing thresholds for designating rapid intensification events, th ...
, leading to Belal becoming a severe tropical storm. As the storm developed a well-defined eye, the MFR upgraded Belal to a tropical cyclone early on 14 January. However, while Belal recurved southeastward, wind shear began to deteriorate the storm's structure into becoming asymmetrical. The eyewall then struck the island of
Réunion Réunion (; ; ; known as before 1848) is an island in the Indian Ocean that is an overseas departments and regions of France, overseas department and region of France. Part of the Mascarene Islands, it is located approximately east of the isl ...
during the next day. The storm briefly weakened back into a severe tropical storm, before again becoming a tropical cyclone on 16 January after organization of the CDO. Weakening then continued from dry air intrusion, causing Belal to become a moderate tropical storm on the next day. By the end of 18 January, Belal had degenerated into a remnant low. As the system developed, the MFR issued a yellow cyclone pre-alert for
Réunion Réunion (; ; ; known as before 1848) is an island in the Indian Ocean that is an overseas departments and regions of France, overseas department and region of France. Part of the Mascarene Islands, it is located approximately east of the isl ...
on 13 January, which was upgraded to an orange cyclone alert on 15:00 UTC the next day. On 13 January, the MMS raised a class I cyclone warning for Mauritius. On 14 January, the MFR upgraded the orange alert into a red alert for
Réunion Réunion (; ; ; known as before 1848) is an island in the Indian Ocean that is an overseas departments and regions of France, overseas department and region of France. Part of the Mascarene Islands, it is located approximately east of the isl ...
as Belal neared the island. The next day, the MFR hoisted a purple alert for Réunion as Belal neared the coast. The
eyewall The eye is a region of mostly calm weather at the center of a tropical cyclone. The eye of a storm is a roughly circular area, typically in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the most severe weath ...
of Belal remained just offshore the northern coast of Réunion during the storm's closest passage. Four people died during the storm in Réunion. Around 150,000 electricity customers lost power, representing more than a third of the island's population. Around 37,000 people lost access to water. Two people died in Mauritius.. After the storm's passage, Mauritius' head of meteorology stepped down after his institution was accused of "not giving adequate warning about the storm’s impact."


Severe Tropical Storm Candice

On 17 January, the MFR noted in its daily bulletin that a strong surge of monsoon flow northeast of the
Mascarenes The Mascarene Islands (, ) or Mascarenes or Mascarenhas Archipelago is a group of islands in the Indian Ocean east of Madagascar consisting of islands belonging to the Republic of Mauritius as well as the French department of Réunion. Their na ...
could produce a precursor
vortex In fluid dynamics, a vortex (: vortices or vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in th ...
. By 22 January, the MFR began releasing warnings on a broad but ill-defined circulation. Convection was offsetted far from the center as the system turns from south to southwest under the influence of a low-level ridge. Upper-level divergence in conjunction with warm sea surface temperatures subdued the effects of vertical shear, enabling consolidation of the disturbance. On 23 January, the JTWC issued a TCFA for the system. The next day, the MFR reported that the system intensified into a tropical depression at 06:00 UTC on 24 January, before the MMS upgraded the system to a moderate tropical storm two hours later, naming it ''Candice''. On 25 January, the JTWC followed suit in recognising the system as Tropical Cyclone 08S. Candice eventually encountered more hostile environmental conditions, as wind shear began to increase dramatically. Convective activity associated with Candice became limited to the cyclone, the MFR estimated that the system had peaked as a severe tropical storm with 10-minute sustained winds of . Environmental conditions and increasingly strong wind shear displaced the storm's convection, weakening it further. Candice degenerated into a post-tropical depression on 27 January as deep convective had ceased, and the final advisory was then issued by MFR. The same day, the JTWC issued its final warning on the system as it became a weakly defined system with an exposed
low-level circulation center The eye is a region of mostly calm weather at the center of a tropical cyclone. The eye of a storm is a roughly circular area, typically in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the most severe weath ...
(LLCC).


Intense Tropical Cyclone Anggrek

On 25 January, Severe Tropical Cyclone Anggrek moved into the basin from the Australian region and was classified as a tropical cyclone. Anggrek strengthened into a Category 3 equivalent cyclone around 09:00 UTC on 26 January, after eye had emerged on satellite imagery, surrounded by a ring of cloud tops. Six hours later, the cyclone maintained a well-defined eye, and the MFR later upgraded the system to an intense tropical cyclone. The cyclone was highly compact, with a distinct eye. The cyclone weakened and bottomed out at on 28 January. Later the next day, the JTWC stated that Anggrek peaked with one-minute sustained winds of —equivalent to a Category 4 hurricane. Around the same time, the convection decreasingly organized and wrapped around the LLCC. The system was moving quickly southeastwards, steered by a ridge to its east. Shortly afterward, Anggrek's cloud pattern slightly deteriorated; it then weakened due to strong wind shear. Soon after, Anggrek's eye gradually disappeared from infrared and visible satellite imagery. The MFR issued its last advisory on the storm as the convective structure weakened further at 18:00 UTC on 30 January. Later the next day, the JTWC discontinued warnings.


Tropical Depression 05

On 25 January, the MFR began highlighting the potential for tropical cyclone development in their daily bulletins, noting an increase in shower activity northeast of St. Brandon. The monsoon trough began to produce persistent convection over the southwestern Indian Ocean. The disturbance continued organizing, and at 00:00 UTC on 30 January, MFR upgraded the system to a tropical disturbance. The same day, the JTWC issued a TCFA for the system as its circulation consolidated, and the next day, it recognised the system as Tropical Cyclone 09S. Convective activity within the disturbance become better organized, resulting in it strengthening to a tropical depression. However, deep convection eventually dissipated, and the system degenerated into a remnant low at 06:00 UTC on 1 February; however, it resumed an increase in convective activity and organization, prompting the MFR to classify the storm as a tropical depression again by the next day. Six hours later, they released their final advisory due to the system being affected by low to moderate wind shear, with its deep convection displaced from the eastern semicircle. The JTWC subsequently issued their final advisory on the system, as its circulation became fully exposed.


Intense Tropical Cyclone Djoungou

On 8 February, MFR's tropical weather discussions began to highlight the possibility of a storm gradually developing in the northeast of the
Mascarene Islands The Mascarene Islands (, ) or Mascarenes or Mascarenhas Archipelago is a group of islands in the Indian Ocean east of Madagascar consisting of islands belonging to the Republic of Mauritius as well as the French department of Réunion. Their na ...
. It gradually organized over favorable environmental conditions with very warm sea surface temperatures and low wind shear. At 00:00 UTC on 15 February, the system was classified as a tropical disturbance. A day later, the system was upgraded to a tropical depression following a significant increase in curved banding. Later that day, the JTWC issued a TCFA, noting a deep convection persisting around the center of circulation. The JTWC upgraded the system to Tropical Cyclone 13S, with the MMS naming it ''Djoungou'' a few hours later as it rapidly organized with deep flaring convection around the system's LLLC. However, multispectral satellite imagery indicated that the cyclone had developed a banding eye feature. As the
eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...
emerged on visible satellite imagery early on 16 February, and at 18:00 UTC that day, the MFR classified Djoungou as a severe tropical storm. However, 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 ir ...
(CDO) developed over Djoungou; it rapidly developed, becoming a Category 1 equivalent cyclone. Soon afterward, the storm structure evolved the eye pattern and was surrounded by intense convective bursts, becoming a tropical cyclone. Later, Djoungou was upgraded to a Category 4 equivalent major cyclone, with one-minute sustained winds estimated at . MFR immediately classified Djoungou as an intense tropical cyclone after the eye gradually improved its convective pattern. However, due to wind shear, the cyclone's increasingly asymmetrical eye disappeared from satellite imagery. Djoungou soon entered into an environment of increasing wind shear, causing its structure to rapidly deteriorate. MFR issued its last advisory on Djoungou as it weakened into a post-tropical depression. On 19 February, Djoungou crossed into the Australian basin to the west-southwest of Learmonth, Western Australia.


Severe Tropical Storm Eleanor

According to the first reports, the damage was light to moderate in Mauritius and La Reunion. In Mauritius, strong winds and heavy rain left at least 2 people injured, 10,000 customers deprived of electricity, several electricity pylons damaged, and trees toppled which blocked several roads. The northern regions suffered the greatest damage.


Severe Tropical Storm Filipo

A report from the National Disasters Management Institute (INGD) on March 15 mentioned 48,000 people affected in the provinces of Gaza, Inhambane, Maputo and Sofala with 2 deaths and 25 injured. It is estimated that 8,000 houses were destroyed or damaged, as well as 51 health centers and 146 schools affected. Rain accumulations were estimated by
weather satellite A weather satellite or meteorological satellite is a type of Earth observation satellite that is primarily used to monitor the weather and climate of the Earth. Satellites are mainly of two types: polar orbiting (covering the entire Earth asyn ...
to be of the order of 130 mm in 24 hours, approximately the normal rainfall for the entire month of March. The Electricidade de Moçambique reported a damage of 10 million meticais (US$157,000) due to Filipo.


Tropical Cyclone Gamane

On 25 March, a zone of disturbed weather emerged 398 nautical miles north-northeast of Toamasina, Madagascar. MFR began issuing bulletins for a potential tropical cyclone that could form in the upcoming days. A few hours later, JTWC followed suit and issued a TCFA, indicating a low-level circulation with a symmetric area of deep persistent convection obscuring the center. On the next day, JTWC designated the disturbance as ''Tropical Cyclone 20S''. A few hours later, 20S rapidly intensified into a severe tropical storm and was assigned the name ''Gamane'' by the MMS. On 27 March, Gamane gained additional strength, further intensifying into a Category 2-equivalent tropical cyclone. Its LLCC continued to improve as it moved into more favorable conditions structurally. At 03:00 UTC, Gamane made landfall on the east coast of Madagascar, just north of Vohémar. From this point, land interaction caused Gamane to weaken significantly — in the morning of 28 March, satellite imagery demonstrated that its deep central and feeder band convection had become disorganized as it tracked inland over the mountainous terrain of Northern Madagascar. MFR issued its final warning after Gamane degenerated into a disturbance on March 28 at 12:00 UTC. According to a preliminary report on 28 March, Gamane generated heavy rains and floods which caused 18 deaths, one missing person, more than 2,500 displaced, and more than 600 houses flooded or damaged in the regions of
Sava The Sava, is a river in Central Europe, Central and Southeast Europe, a right-bank and the longest tributary of the Danube. From its source in Slovenia it flows through Croatia and along its border with Bosnia and Herzegovina, and finally reac ...
,
Analanjirofo Analanjirofo is a region in northeastern Madagascar. Until 2009 it was a part of Toamasina Province. It borders Sava Region to the north, Sofia Region to the west, Alaotra-Mangoro Region to the southwest and Atsinanana Region to the south. The c ...
and Diana. The authorities reported that Sambava District received 300 mm of rain in 24 hours. Accessibility to this region is difficult in normal times and the road connecting it to the capital has been cut by the rain, which makes the arrival of aid very slow. On April 3, the total was raised to 19 deaths, 3 people missing and at least 90,000 affected. Overall, the cyclone caused a loss of 339 billion
ariary The ariary (currency sign, sign: Ar; ISO 4217 code MGA) is the currency of Madagascar. It is notionally subdivided into 5 ''iraimbilanja'' and is one of only two non-decimal currencies currently circulating (the other is the ''Mauritanian ouguiya ...
(US$77.4 million) on the island.


Tropical Cyclone Hidaya

On 30 April, a zone of disturbed weather was formed near
Seychelles Seychelles (, ; ), officially the Republic of Seychelles (; Seychellois Creole: ), is an island country and archipelagic state consisting of 155 islands (as per the Constitution) in the Indian Ocean. Its capital and largest city, Victoria, ...
. Later, MFR started issuing initial advisories that could form in the following days. JTWC followed suit and also issued a TCFA. On 2 May, its LLCC became organized, which resulted in gaining the name ''Hidaya'' from the MMS. JTWC also followed suit and gave its identifier as ''Tropical Cyclone 23S''. Hidaya's low-level circulation center and its deep convective banding began to wrap into the system along the southern semicircle of the system. On 3 May, Hidaya rapidly intensified into a Category-1 cyclone after it drastically symmetrized over the past 12 hours. Later that day, Hidaya peaked with 1-minute sustained winds of 80 knots. As it approached
Tanzania Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...
, Hidaya was downgraded back into a severe tropical storm. Satellite imagery shows that it began rapidly eroding, with its convective activity diminished, and the cloud tops considerably warmed. At 14:00 UTC, Hidaya made landfall in Kilindoni, Tanzania as a weakening tropical storm. Signs of rapid weakening ensued as it moved inland. All agencies discontinued their advisories on May 4 as Hidaya further moved through landmass. Hidaya was a rare example in recorded history of a tropical cyclone or depression making landfall in Tanzania, other examples being a cyclone passing over Zanzibar in 1872, an unnamed cyclone in 1952 and Tropical Depression Atang in 2002. Additionally, it was the most intense recorded cyclone to occur in this region in the Indian ocean. Due to the storm, ferry service between
Zanzibar Zanzibar is a Tanzanian archipelago off the coast of East Africa. It is located in the Indian Ocean, and consists of many small Island, islands and two large ones: Unguja (the main island, referred to informally as Zanzibar) and Pemba Island. ...
and
Dar es Salaam Dar es Salaam (, ; from ) is the largest city and financial hub of Tanzania. It is also the capital of the Dar es Salaam Region. With a population of over 7 million people, Dar es Salaam is the largest city in East Africa by population and the ...
was temporarily halted. The cyclone struck after weeks of flooding across the region, adding to the destruction and death toll. Hidaya killed at least five people in Tanzania, including a fisherman from
Pemba Island Pemba Island (; ''al-Jazīra al-khadrāʔ''; ; ) is a Tanzanian island forming part of the Zanzibar Archipelago, lying within the Swahili Coast in the Indian Ocean. Geography file:Map of Zanzibar Archipelago-en.svg, left, The main islands of the ...
who drowned during the storm. The storm also damaged or destroyed 1,555 houses, while also washing out a portion of the Lindi-Dar es Salaam highway. Hidaya's wind gusts also knocked down trees and also resulted in power outages. According to the
World Bank The World Bank is an international financial institution that provides loans and Grant (money), grants to the governments of Least developed countries, low- and Developing country, middle-income countries for the purposes of economic development ...
, damage across the nation were about US$184.45 million.


Tropical Cyclone Ialy

On 13 May, 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 ...
began monitoring a low-level circulation which persisted 588 nm east-northeast of
Comoros The Comoros, officially the Union of the Comoros, is an archipelagic country made up of three islands in Southeastern Africa, located at the northern end of the Mozambique Channel in the Indian Ocean. Its capital and largest city is Moroni, ...
, stating it was in a favourable environment to intensify. Two days later, the JTWC upgraded its chance of developing to medium as the circulation consolidated. By 16 May, the JTWC issued a TCFA on the burgeoning system, stating that deep convection was occurring on the southern portion of the system. Soon after, the MFR recognized the circulation as a zone of disturbed weather. Soon afterwards, the MMS received the name ''Ialy'' after the agency upgraded the system into a tropical storm. The JTWC then also recognised the system as a cyclone, issuing warnings on it as ''Tropical Cyclone 24S''. Steadily intensifying, Ialy reached an initial peak intensity with 1-minute sustained winds of the next day before wind shear began eroding the system. On May 19, Ialy was upgraded into a severe tropical storm by the MFR as the system became more compact. Ialy battled through high shear and became a Tropical Cyclone per MFR and a Category 1-equivalent cyclone per JTWC during the afternoon of May 21 local time. However, shear rapidly overcame Ialy, and 24 hours after peaking, Ialy had degenerated into a weak low pressure system per MFR. The JTWC also issued their final warning early on May 22 as Ialy was about to fall below tropical storm strength and was starting to rapidly dissipate just offshore Kenya. In Kenya, the cyclone killed two people. Strong winds tore off the roof of a school, killing a girl and injuring four others, while another person died due to a fallen wall. Ialy is notable for being the strongest cyclone to have ever affected Kenyan waters and the first to directly affect the country since the beginning of reliable records.


Other systems

* On 24 March, the remnants of Cyclone Neville entered the area of responsibility of
Météo-France Météo-France is the official French meteorological administration, also offering services to Andorra and Monaco. It has the powers of the state and can exercise them in relation to meteorology. Météo-France is in charge of observing, study ...
(MFR) after crossing the 90th meridian east from the Australian region. At the time, the system was assessed as a filling depression, with maximum 10-minute sustained winds of and a central
atmospheric pressure Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1,013. ...
of . Due to the decreased convective activity, it was agreed that the MFR would not provide official information on the system. The cyclone's convective structure swiftly deteriorated, and Neville's LLLC soon became exposed, causing the United States
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) to discontinue advisories. Afterwards, the system was last mentioned by the MFR while located approximately to the west of Learmonth, Western Australia. * On 17 May, a low-level circulation formed north of
Diego Garcia Diego Garcia is the largest island of the Chagos Archipelago. It has been used as a joint UK–U.S. military base since the 1970s, following the expulsion of the Chagossians by the UK government. The Chagos Islands are set to become a former B ...
. On 19 May, the JTWC declared that the cyclone, designated 25S, had formed abnormally close to the Equator. However, MFR did not recognize this system as a tropical cyclone, and gave it a high chance of developing into a tropical storm. It dissipated due to being in a extremely unfavorable environment by 21 May.


Storm names

Within the South-West Indian Ocean, tropical and subtropical cyclones that are judged to have 10-minute sustained winds of 65 km/h (40 mph) by the
Regional Specialized Meteorological Center A Regional Specialized Meteorological Centre (RSMC) is responsible for the distribution of information, advisories, and warnings regarding the specific program they have a part of, agreed by consensus at the World Meteorological Organization as ...
on
Réunion Réunion (; ; ; known as before 1848) is an island in the Indian Ocean that is an overseas departments and regions of France, overseas department and region of France. Part of the Mascarene Islands, it is located approximately east of the isl ...
island, France (RSMC La Réunion) are usually assigned a name by the Sub-Regional Tropical Cyclone Advisory Centers in Mauritius and Madagascar. The Sub-Regional Tropical Cyclone Advisory Center (Mauritius Meteorological Services) in Mauritius names cyclones when they intensify into a moderate tropical storm between 55°E and 90°E, while the Sub-Regional Tropical Cyclone Advisory Center (Meteo Madagascar) in Madagascar names cyclones when they intensify into a moderate tropical storm between 30°E and 55°E. Storm names are taken from three pre-determined lists of names, which rotate on a triennial basis, with names used in the season being automatically removed. The new names this season are Alvaro, Belal, Candice, Djoungou, Eleanor, Filipo, Gamane, Hidaya, Ialy, and Jeremy which replaced Alicia, Bongoyo, Chalane, Danilo, Eloise, Faraji, Guambe, Habana, Iman, and Jobo in the 2020–21 season. If a tropical cyclone enters the South-West Indian basin from the Australian region basin (west of 90°E), it will retain the name assigned to it by the
Bureau of Meteorology The Bureau of Meteorology (BOM or BoM) is an executive agency of the Government of Australia, Australian Government that is responsible for providing Weather forecasting, weather forecasts and Meteorology, meteorological services to Australia a ...
(BoM) or the
Meteorology, Climatology, and Geophysical Agency Meteorology, Climatology, and Geophysical Agency (, abbreviated BMKG) is an Indonesian non-departmental government agency for meteorology, climatology, and geophysics. History Its history began on 1841 with individual observation conducted by ...
(BMKG). The following storms were named in this manner:


Season effects

This table lists all of the
tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...
and
subtropical cyclone A subtropical cyclone is a weather system that has some characteristics of both tropical cyclone, tropical and extratropical cyclones. As early as the 1950s, meteorologists were uncertain whether they should be characterized as Tropical cyclone ...
s that were monitored during the 2023–2024 South-West Indian Ocean cyclone season. Information on their intensity, duration, name, areas affected, primarily comes from RSMC La Réunion, however, death and damage reports come from either press reports or the relevant national disaster management agency. The damage totals are given in 2023 or 2024 USD. , - , , , , , bgcolor=#, , , bgcolor=#, , , bgcolor=#, , ,
Mozambique Mozambique, officially the Republic of Mozambique, is a country located in Southeast Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west, and Eswatini and South Afr ...
,
Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...
, , , , , , , - , , , , , bgcolor=#, , , bgcolor=#, , , bgcolor=#, , ,
Mascarene Islands The Mascarene Islands (, ) or Mascarenes or Mascarenhas Archipelago is a group of islands in the Indian Ocean east of Madagascar consisting of islands belonging to the Republic of Mauritius as well as the French department of Réunion. Their na ...
, , , , , , , - , , , , , bgcolor=#, , , bgcolor=#, , , bgcolor=#, , , Mauritius , , , , , , , - , , , , , bgcolor=#, , , bgcolor=#, , , bgcolor=#, , , None , , , , , , , - , , , , , bgcolor=#, , , bgcolor=#, , , bgcolor=#, , , None , , , , , , , - , , , , , bgcolor=#, , , bgcolor=#, , , bgcolor=#, , , None , , , , , , , - , , , , , bgcolor=#, , , bgcolor=#, , , bgcolor=#, , ,
Mauritius Mauritius, officially the Republic of Mauritius, is an island country in the Indian Ocean, about off the southeastern coast of East Africa, east of Madagascar. It includes the main island (also called Mauritius), as well as Rodrigues, Ag ...
,
Réunion Réunion (; ; ; known as before 1848) is an island in the Indian Ocean that is an overseas departments and regions of France, overseas department and region of France. Part of the Mascarene Islands, it is located approximately east of the isl ...
, , , , , , , - , , , , , bgcolor=#, , , bgcolor=#, , , bgcolor=#, , , Madagascar,
Mayotte Mayotte ( ; , ; , ; , ), officially the Department of Mayotte (), is an Overseas France, overseas Overseas departments and regions of France, department and region and single territorial collectivity of France. It is one of the Overseas departm ...
,
Mozambique Mozambique, officially the Republic of Mozambique, is a country located in Southeast Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west, and Eswatini and South Afr ...
,
Eswatini Eswatini, formally the Kingdom of Eswatini, also known by its former official names Swaziland and the Kingdom of Swaziland, is a landlocked country in Southern Africa. It is bordered by South Africa on all sides except the northeast, where i ...
,
South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...
, , , , , , , - , , , , , bgcolor=#, , , bgcolor=#, , , bgcolor=#, , , None, , , , , , , - , , , , , bgcolor=#, , , bgcolor=#, , , bgcolor=#, , , Madagascar , , , , , , , - , , , , , bgcolor=#, , , bgcolor=#, , , bgcolor=#, , ,
Seychelles Seychelles (, ; ), officially the Republic of Seychelles (; Seychellois Creole: ), is an island country and archipelagic state consisting of 155 islands (as per the Constitution) in the Indian Ocean. Its capital and largest city, Victoria, ...
,
Comoro Islands The Comoro Islands are a group of volcanic islands in the Mozambique Channel, an arm of the Indian Ocean lying between Madagascar and the African mainland. Three of the islands form the Union of the Comoros, a sovereign nation, while Mayotte bel ...
,
Tanzania Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...
,
Kenya Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...
, , , , , , , - , , , , , bgcolor=#, , , bgcolor=#, , , bgcolor=#, , , Seychelles, Madagascar, Tanzania, Kenya,
Somalia Somalia, officially the Federal Republic of Somalia, is the easternmost country in continental Africa. The country is located in the Horn of Africa and is bordered by Ethiopia to the west, Djibouti to the northwest, Kenya to the southwest, th ...
, , , , , ,


See also

* Weather of 2023 and
2024 The year saw the list of ongoing armed conflicts, continuation of major armed conflicts, including the Russian invasion of Ukraine, the Myanmar civil war (2021–present), Myanmar civil war, the Sudanese civil war (2023–present), Sudane ...
*
List of Southern Hemisphere cyclone seasons The tropical cyclone seasons that occur in the Southern Hemisphere are: *South-West Indian Ocean tropical cyclone **Current – South-West Indian Ocean cyclone season *Australian region tropical cyclone An Australian region tropical cyclone ...
*Tropical cyclones in
2023 Catastrophic natural disasters in 2023 included the Lists of 21st-century earthquakes, 5th-deadliest earthquake of the 21st century 2023 Turkey–Syria earthquakes, striking Turkey and Syria, leaving up to 62,000 people dead; Cyclone Freddy ...
and
2024 The year saw the list of ongoing armed conflicts, continuation of major armed conflicts, including the Russian invasion of Ukraine, the Myanmar civil war (2021–present), Myanmar civil war, the Sudanese civil war (2023–present), Sudane ...
*Atlantic hurricane seasons:
2023 Catastrophic natural disasters in 2023 included the Lists of 21st-century earthquakes, 5th-deadliest earthquake of the 21st century 2023 Turkey–Syria earthquakes, striking Turkey and Syria, leaving up to 62,000 people dead; Cyclone Freddy ...
,
2024 The year saw the list of ongoing armed conflicts, continuation of major armed conflicts, including the Russian invasion of Ukraine, the Myanmar civil war (2021–present), Myanmar civil war, the Sudanese civil war (2023–present), Sudane ...
*Pacific hurricane seasons:
2023 Catastrophic natural disasters in 2023 included the Lists of 21st-century earthquakes, 5th-deadliest earthquake of the 21st century 2023 Turkey–Syria earthquakes, striking Turkey and Syria, leaving up to 62,000 people dead; Cyclone Freddy ...
,
2024 The year saw the list of ongoing armed conflicts, continuation of major armed conflicts, including the Russian invasion of Ukraine, the Myanmar civil war (2021–present), Myanmar civil war, the Sudanese civil war (2023–present), Sudane ...
*Pacific typhoon seasons:
2023 Catastrophic natural disasters in 2023 included the Lists of 21st-century earthquakes, 5th-deadliest earthquake of the 21st century 2023 Turkey–Syria earthquakes, striking Turkey and Syria, leaving up to 62,000 people dead; Cyclone Freddy ...
,
2024 The year saw the list of ongoing armed conflicts, continuation of major armed conflicts, including the Russian invasion of Ukraine, the Myanmar civil war (2021–present), Myanmar civil war, the Sudanese civil war (2023–present), Sudane ...
*North Indian Ocean cyclone seasons:
2023 Catastrophic natural disasters in 2023 included the Lists of 21st-century earthquakes, 5th-deadliest earthquake of the 21st century 2023 Turkey–Syria earthquakes, striking Turkey and Syria, leaving up to 62,000 people dead; Cyclone Freddy ...
,
2024 The year saw the list of ongoing armed conflicts, continuation of major armed conflicts, including the Russian invasion of Ukraine, the Myanmar civil war (2021–present), Myanmar civil war, the Sudanese civil war (2023–present), Sudane ...
* 2023–24 Australian region cyclone season * 2023–24 South Pacific cyclone season


References


External links


Météo-France La Réunion
*
Alternative website

Direction Générale de la Météorologie de Madagascar

Mauritius Meteorological Services


{{DEFAULTSORT:2023-24 South-West Indian Ocean cyclone season * 2023-24