User:JCMLuis/2018-19 South-West Indian Ocean cyclone season

The 2018–19 South-West Indian Ocean cyclone season was the costliest and the most active season ever recorded. Additionally, it is also the deadliest cyclone season recorded in the South-West Indian Ocean, surpassing the 1891–92 season in which the 1892 Mauritius cyclone devastated the island of Mauritius, and is mainly due to Cyclone Idai. The season was an event of the annual cycle of tropical cyclone and subtropical cyclone formation in the South-West Indian Ocean basin. It officially began on 15 November 2018, and ended on 30 April 2019, except for Mauritius and the Seychelles, which it ended on 15 May 2019. 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. Tropical and subtropical cyclones in this basin are monitored by the Regional Specialised Meteorological Centre in Réunion.

Two tropical cyclones existed outside the conventional bounds of the season, with Moderate Tropical Storm 01 in September and the remnants of Tropical Cyclone Lorna in May. From all of these cyclones during the season, all but Haleh and Savannah produced impacts on land. The season set a new record of nine intense tropical cyclones, the largest number since the start of reliable satellite coverage in 1967, surpassing the 2006–07 season. Besides the aforementioned Moderate Tropical Storm 01, two other systems formed prior to the official start of the season—the first intense tropical cyclone, Alcide, and Severe Tropical Storm Bouchra. A pair of intense tropical cyclones—Cilida and Kenanga—persisted in December; Cilida only brought gusting winds and rain Mauritius. In January 2019, Desmond induced damages in Mozambique and killed 3, and shortly thereafter, Eketsang passed by Madagascar, killing 27. Onto the next month, Funani and Gelena threatened Rodrigues, with the latter disrupting its electricity.

The most active and destructive month was March. Haleh formed on the 1 March, tracking towards the South Pole and bringing no impact. Cyclone Idai made two landfalls in Mozambique as a tropical depression and intense tropical cyclone, causing at least 1,593 deaths and leaving at least 2,262 people missing, and causing US$3.3 billion in damages in Mozambique, Zimbabwe, Malawi, and Madagascar. Savannah entered the basin in the middle of the month. Joaninha became the second cyclone of 2019 to strike Rodrigues, destroying the island's power grid. In April, Kenneth killed at least 7 people in Comoros and made landfall in Mozambique, causing at least 45 deaths. Lorna remained over the eastern portion of the basin, concluding the season after it dissipated on 29 April.

Seasonal forecasts
On 24 October 2018, the Mauritius Meteorological Services (MMS) released their summer 2018–19 outlook. The agency expected a slightly-below to near-average season, predicting that 7 to 9 tropical cyclones would form. In addition, the MMS indicated that conditions in the central tropical Indian Ocean and between Diego Garcia and Agalega, or west of the 70th meridian east, would be more conducive for tropical cyclogenesis.

Météo-France announced their seasonal forecast of tropical cyclone activity on 15 November, after the formation of 01, Alcide, and Bouchra. Despite this, the MFR forecasted a nearly-average season, citing the conditions of an El Niño event. Compared to an average of ten moderate tropical storms that usually form in the South-West Indian Ocean, a 20% chance was given to the probability of below-average activity. A 60% chance was given to near-average activity, and a 20% chance was given to above-average activity. MFR expected that 8 to 11 systems would form, with 4 to 6 of them reaching the tropical cyclone stage. The agency indicated that cyclogenesis would mainly occur over the central Indian Ocean and western portion of the basin The MFR also predicted that the motion of cyclones during the season would have a stronger meridional component than normal, having a tendency to track south quickly.

The forecasts from the MFR failed to predict enhanced activity over the Mozambique Channel, and hypothesised that most of the energy for cyclone formation was caused by strong equatorial waves activity. For future operations, MFR planned to target inhabited areas.

Seasonal summary
The 2018–19 South-West Indian Ocean cyclone season officially ran from 15 November 2018 to 30 April 2019, with the exception for the island nations of Mauritius and Seychelles, which ended on 15 May 2019. The season was the costliest, deadliest, and most active since reliable records began in 1967. Collectively, the systems caused 1,675 deaths and about $3.65 billion in damage, and is mainly attributed to Cyclone Idai, which caused 1,593 deaths and $3.3 billion in damages. Almost every system had produced impacts on land except Haleh and Savannah. Throughout the season, 15 tropical disturbances formed, all of which reached the moderate tropical storm stage. Eleven of these storms attained tropical cyclone status, and all but two—Savannah and Lorna—reached the intense tropical cyclone stage, breaking the previous record of having the most intense tropical cyclones held by the 2006–07 season, which had six. Regardless to the activity, there were no systems in this season that acquired the strength of a very intense tropical cyclone—the highest classification in MFR's intensity scale.

Météo-France's meteorological office in Réunion (MFR) – the official Regional Specialized Meteorological Center for the South-West Indian Ocean – tracked all tropical cyclones from the east coast of Africa to 90° E, and south of the equator. Regional warning centers in Mauritius and Madagascar formally named the individual storms. The Joint Typhoon Warning Center (JTWC), which is a joint United States Navy – United States Air Force task force that issues tropical cyclone warnings for the region, also issued advisories for storms during the season.

Pre/early season activity
The season abruptly began with the formation of Moderate Tropical Storm 01 on 14 September 2018. After two months of inactivity, a tropical disturbance formed. This system developed into a tropical depression and then to a tropical cyclone on 7 November receiving the name Alcide. Its eye reached the dependency of Agaléga, damaging homes and causing an injury. The storm steered northwestward, and concurrently, a tropical disturbance at the eastern border of the basin formed on 9 November. As Alcide dissipated on 11 November, with its remnants last noted on 14 November, the embryonic system oscillated around the 90th meridian east for several days. The disturbance intensified into Severe Tropical Storm Bouchra during the period, and eventually stayed within the basin on 17 November, before dissipating on 20 November.

Two storms emerged in the month of December: Kenanga and Cilida. The former entered the basin from the Australian region on 16 December, whereas the latter developed from the monsoon trough to a tropical depression two days later. Kenanga attained intense tropical cyclone status on 18 December, as Cilida headed towards Mauritius. Simultaneously on 20 December, both storms were tropical cyclones within the basin, the first such case since the 2013–14 season. Also peaking as an intense tropical cyclone, Cilida brought beneficial rain and strong winds to Mauritius. Both storms then weaken from hostile conditions. Cilida dragged Kenanga southward towards itself, and both storms had dissipated by 24 December.

Peak to late activity
Around January 2019, Desmond formed over the Mozambique Channel. The storm went westward before taking a north-northwest path to the country of Mozambique, where it brought destruction and caused casualties. Another storm then formed a day after Desmond dissipated. This system was named Eketsang and passed by southern Madagascar with heavy rains, killing 27. In February, another pair of tropical cyclones occurred, being Funani and Gelena. Both systems threatened Mauritius, particularly Rodrigues, with Gelena leaving many people in Rodrigues without electricity. An active phase of the Madden–Julian oscillation contributed to the formation of Intense Tropical Cyclone Haleh on 1 March. The storm mainly tracked south-southwestward and did not affect land. On 4 March, a tropical depression formed near the Mozambican coast. It moved overland for several days, killing 56 people in Malawi and 66 in Mozambique, before returning to the sea on 9 March. The storm rapidly intensified into Intense Tropical Cyclone Idai and made a turn towards Mozambique. Idai made a second landfall on 14 March, bringing catastrophic damage and killing over a thousand people in southern African countries. A tropical cyclone entered the basin on 18 March after it had peaked in intensity, being Savannah. It rapidly weakened from wind shear and dissipated on 19 March. A system formed on 21 March, and subsequently became Moderate Tropical Storm Joaninha on that day. It peaked as an intense tropical cyclone on 25 March, before passing close to Rodrigues, destroying the island's power grid.

The month of April had the last two systems, Kenneth and Lorna. Kenneth formed east of the Chagos Archipelago, generally tracked westward, before making landfall in Mozambique and killing at least 45. Meanwhile, Lorna moved southeastward, peaking as a tropical cyclone on 28 April, and dissipated on 29 April.

Moderate Tropical Storm 01
Within the Intertropical Convergence Zone (ITCZ), an equatorial Rossby wave led to the formation of a weak cyclonic circulation near -7°N, 75°W on 13 September, with intense convection, or thunderstorms, fluctuating in the system. A Kelvin wave and the subtropical jet sustained the system, but it was forecasted that it would not undergo deepening and will fill up. East of the Chagos Archipelago, the system consolidated into a tropical disturbance on 14 September, retaining a well-defined centre, accommodated by sufficient ocean heat content. Moving southwestward, it began possessing nascent rainbands. Despite low vertical wind shear and improving poleward outflow, marginal sea surface temperatures of 26 C limited development of the compact disturbance. The MFR upgraded the disturbance to a tropical depression later that day. Operationally, the system peaked as a tropical depression, but was upgraded by the MFR to a moderate tropical storm after post-season analysis, though the cyclone remained unnamed. The storm then begin to track over a hostile environment of moderate wind shear, dry air entrainment in the mid-level troposphere, and cooler waters. Turning westward, the storm failed to organised its deep convection, leading to its centre becoming exposed, albeit still being defined. It weakened into a low at 12:00 UTC, before dissipating two days later at 06:00 UTC.

Intense Tropical Cyclone Alcide
In early-November, low-level vorticity inside the ITCZ indicated the possibility of tropical cyclogenesis between the Chagos Archipelago and Seychelles. The arrival of an active phase of the Madden–Julian oscillation boosted this potential, prompting MFR to categorise the likelihood of a tropical storm within the next five days to high. Eventually on 6 November, a tropical disturbance formed after convection organised around a surface circulation over the previous day. Initially inhibited by dry air intrusion, the system intensified into a tropical depression, moving west-southwest along a ridge to the southeast, following strong bursts of convection over the centre. Convective cloud tops of -90 C signaled an improvement in the centre; as such, the system was upgraded to a moderate tropical storm, receiving the name Alcide from the Mauritius Meteorological Services (MMS). Alcide then became the first severe tropical storm of the season on 7 November. While attaining Category 1 strength on the Saffir–Simpson scale (SSHWS), Alcide presented a 15 nmi ragged eye, as convective bands tightened into the core. Alcide was upgraded to a tropical cyclone at 06:00 UTC, with its eye hovering over Agaléga.

Benefiting from strong poleward outflow, the symmetrical cyclone quickly intensified into a Category 3-equivalent tropical cyclone on 8 November. At 03:00 UTC, 1-minute winds were estimated to be 115 kn—equivalent to a Category 4 hurricane. The MFR also upgraded Alcide to an intense tropical cyclone, as the storm peaked with 10-minute winds of 100 kn. Likewise to the previous system, Alcide was characterised as a small cyclone. The eye then became cloud-filled, progressively becoming ragged and disorganised. By 18:00 UTC, Alcide was no longer an intense tropical cyclone. Cloud tops warmed around the centre, obscured by a layer of cirrus clouds. With no steering flow, Alcide was nearly stationary, as dry air intrude the inner core. Consequently, upwelling prevailed, as outflow diminished, weakening convection. On 9 November, Alcide was downgraded to a severe tropical storm. On the next day, the JTWC assessed Alcide's winds as being tropical storm-force. Alcide began turning northwestward, though the cloud pattern significantly decayed and deep convection had collapsed in the eastern quadrant. By 11 November, the MFR categorised Alcide as a tropical depression, citing the lack of deep convection and exposal of the circulation. The storm disintegrated into a remnant low on 12 November, before dissipating on 14 November.

While Alcide approached the archipelago of Agaléga, 75 residents evacuated from South Island to a refuge center in North Island. On 7 November, Alcide made its closest approach to Agaléga, with wind gusts of 110 km/h recorded by a weather station. At the time, 45 people sought shelter centers, as many trees were down and electricity and water distribution was disrupted. As a result, several homes were left without power. Many houses were damaged and a 15-year-old girl was injured in addition. After the storm had passed, metal roofs of around thirty homes awaited repairment.

Severe Tropical Storm Bouchra
A weak low-pressure system developed in the equatorial Indian Ocean in Météo-France's area of responsibility on November 1 and moved slowly eastwards over the following few days while showing little signs of intensification. Late on November 9, as the developing precursor depression to Very Severe Cyclonic Storm Gaja in the Bay of Bengal moved further away and the competing low-level airflow convergence associated with it diminished, which was earlier associated with the westerly wind burst on either side of Indian Ocean. the system's structure organised sufficiently to be classified as a tropical disturbance by Météo-France. Very shortly afterwards, the system crossed the 90th meridian east and entered the Australian region, where it was classified by TCWC Jakarta as a tropical depression on November 10 local time. Later the same day, the JTWC assessed the developing low as having attained tropical storm status on the Saffir–Simpson hurricane wind scale, and assigned the system the unofficial designation 04S. A few hours later, at 10:00 UTC, the system moved back westwards and returned to the South-West Indian Ocean basin, where it gained the name 'Bouchra' from Météo-France and underwent a twelve-hour phase of rapid intensification to severe tropical storm status.

Over the following days, Bouchra fought increasingly unfavorable atmospheric conditions, and underwent a gradual weakening trend. During this time, the cyclone proceeded to track in a slow cyclonic loop just to the west of the border of the Australian region in weak overall steering influences, and was often quasi-stationary. After meandering here for a number of days, the system re-entered the Australian region late on November 12. By this stage, the system had weakened significantly from its peak intensity, and was only at tropical depression strength. The period of residence in the Australian basin proved to be short-lived once again, however, with Météo-France indicating that Ex-Tropical Storm Bouchra had returned to the far eastern part of their area of responsibility early on November 13. In the early hours of November 14, the Australian Bureau of Meteorology noted that the system had crossed back into the Australian region basin. However, on November 17, Bouchra crossed back over into the South-West Indian Ocean basin, as the storm began taking a southwestward trajectory.

Intense Tropical Cyclone Kenanga
On 16 December, Tropical Cyclone Kenanga from the Australian region entered the basin, retaining its name from TCWC Jakarta and becoming re-classified as a moderate tropical storm. The storm's acceleration southwest circumvented the effects of vertical wind shear, facilitating the formation of a central dense overcast. Owing to favorable upper-level conditions, Kenanga transitioned into an annular tropical cyclone on 18 December. The storm quickly intensified, peaking with 10-minute winds of 100 kn assessed by MFR and Category 4-equivalent winds of 115 kn assessed by the JTWC early on the next day. Kenanga maintained its annular characteristics while dry air began to weaken convection over the southeast quadrant. Throughout the day, Kenanga held the intense tropical cyclone threshold until 20 December, when convective clouds began to warm up, signaling a weakening trend. The eye disappeared, as the cyclone, located 773 nmi southeast of Diego Garcia, tracked over an area of high wind shear and cooler waters. Moving westward, Kenanga weakened into a severe tropical storm from dry air on 21 December. By the next day, the large and ragged circulation became exposed on satellite imagery. Kenanga continued to deteriorate into a moderate tropical storm, steering southward under the influence of Cyclone Cilida southwest of the storm. Early on the next day, the MFR categorised Kenanga as a remnant low. With no thunderstorm activity in the system's centre, the MFR issued its final bulletin. Kenanga persisted for three more days before dissipating on 26 December.

Intense Tropical Cyclone Cilida
Around the same time as Kenanga's genesis, a cyclonic gyre west of Diego Garcia was detected within the monsoon trough. Convection organised around the low-pressure area for several days, and on 18 December, the MFR began issuing advisories on the system. The MFR further upgraded the disturbance to a tropical depression on the same day. On 19 December, the cyclone strengthened into a moderate tropical storm, prompting the MMS to give it the name Cilida. Cilida experienced steady intensification from outflow and warm seas, possessing fragmented rudimentary rainbands that mainly spiraled from the east. As time passed by, thunderstorms coalesced to form a dense overcast. Drifting southwestward, Cilida intensified into a severe tropical storm on 20 December. A period of rapid intensification caused by dual outflow channels then ensued; the eye pattern varied, surrounded by very cold cloud tops. Alongside Kenanga, Cilida was one of the first two tropical cyclones in the basin to exist simultaneously since Intense Tropical Cyclone Amara and Very Intense Tropical Cyclone Bruce of the 2013–14 season.

By the next day, Cilida had attained its peak intensity; the MFR estimated winds of 115 kn. Meanwhile, the JTWC estimated high-end Category 4-equivalent winds of 135 kn. On 22 December, convection in the western sector had weakened, indicating an eyewall replacement cycle, as Cilida started steering southeast. The cycle concluded the next day with a larger eye, though it was not well-defined. Cilida made its closest approach of Mauritius, being slightly below 240 km to the northeast. An increase in wind shear and decrease in sea surface temperatures gradually unraveled rainbands, suppressing outflow and weakening the storm. On 24 December, Cilida was downgraded to a severe tropical storm, and was later labeled a post-tropical depression at 18:00 UTC. The vortex elongated as the asymmetrical and shallow storm transitioned into an extratropical cyclone. It degenerated into a remnant low, before dissipating during 28 December.

Ahead of Cilida, Air Mauritius suspended all flights to Rodrigues. On 23 December, Cilida passed east of Mauritius, bringing beneficial rainfall and gusting winds that knocked down tree branches, blocking roads.

Moderate Tropical Storm Desmond
During the middle of January 2019, strong convection caused by converging trade winds persisted over the western half of the basin, organising around a low along the coast of southern Mozambique. The low spent days above the country moving east-northeast, before moving towards the sea, where it was designated a tropical disturbance on 18 January. It presented a weak structure to satellite imagery, with an ill-defined, exposed circulation holding convection to its east, accompanied by multiple vortices. However, the centre consolidated shifting northward, and on 19 January, the system strengthened into a tropical depression, before additionally organising into a moderate tropical storm later that day. Convection within the storm nearly collapsed, but was it was halted by a new cluster of thunderstorms, as Desmond recurved to a west-northwest track. Northwest of Europa Island, Desmond situated in a marginal environment of high wind shear and dry air alleviated by strong outflow, with its centre obscured by cirrus clouds. Towards the end of 21 January, Desmond made landfall near Quelimane in Mozambique, rapidly weakening overland and dissipating on 22 January.

Though the storm did not strike Madagascar, it enhanced rains in the northwest portion of the island. Desmond induced heavy flooding upon Beira, Chinde, and Quelimane in Mozambique, displacing around 120,000 people across the provinces of Zambezia, Sofala, Manica, and Tete. 277 mm of 24-hour rain was recorded in Beira. Large waves smashed through sea defences, as the torrential rain flooded roads. Cars were submerged as floodwater entered people's homes and businesses. It destroyed infrastructure and minimally impacted crops. Approximately 60000 hectare of crops were affected and over 1,000 livestock were killed. Three people were killed in the country. The storm then reached Malawi with minor effects. In the aftermath of the storm, the Mozambique National Institute of Disaster Management deployed drones to assess affected areas and set up evacuation routes, with the assistance of the European Union's Emergency Management Service.

Moderate Tropical Storm Eketsang
A poorly-defined low northeast of Madagascar was detected by MFR on 19 January; the agency suggested that it would enter favorable conditions in the Mozambique Channel in the upcoming days. Along its path, the system poured rainfall over northern regions of Madagascar. The broad low then reached offshore, but its structure was not yet unified, though it was aided by warm seas and equatorial low-level convergence. By 23 January, the system evolved into a tropical disturbance, before additionally intensifying into a tropical depression, as thunderstorms obscured the defined centre. On 24 January, the system attained moderate tropical storm status, gaining the name Eketsang from the meteorological service of Madagascar (Météo Madagascar). Traversing southeast, Eketsang quickly began interacting with the baroclinic zone associated with an upper-level trough. By the following day, the storm became post-tropical, as the circulation continued to elongate and be disorganised. It was last noted on 26 January. The storm's remnants formed a cold front that affected the weather in the Mascarene Islands and extended over the Mozambique Channel, bringing thunderstorms over Comoros and Mayotte.

Eketsang induced westerly winds that brought moisture from the Congo Basin to Tanzania. Prior to the storm's arrival, a yellow alert was issued for the regions of Atsimo-Andrefana, Androy, and Anosy in Madagascar, in addition to a heavy rain watch for the districts of Maintirano, Antsalova, Belo Tsiribihina, Morondava, and Manja. The storm produced double the expected rainfall for the month of January. Eketsang passed by southern Madagascar with heavy rains, killing 27 people, 18 of which were from landslides, 4 of which were from drowning, and the rest being from collapsing buildings. A person was also reported missing. 9,000 people were affected, with over 2,000 being displaced, as 1,778 homes were inundated and 187 were destroyed. The towns of Ambilobe, Antsiranana, and Morondava suffered the brunt of the storm, as roads became impassable.

Intense Tropical Cyclone Funani
Towards the end of January, zonal thunderstorm activity increased due to the entry of a Kelvin wave and the approach of an equatorial Rossby wave, giving the basin a potential of producing two low-level circulations, including one south of the Chagos Archipelago. Over the following days, convection was maintained in an unorganised circulation, but on 4 February, it was marked a tropical disturbance by MFR and later a tropical depression. Though its center was structured, dry air advected by trade winds obstructed intensification. Convection then became much more concentrated under weak vertical wind shear, leading to the cyclone intensifying into a tropical storm on 5 February and receive the name Funani from the MMS. Funani moved southwestward, before taking a southeast turn around a ridge to its east. An ill-defined eye appeared over the asymmetrical storm, with convection primarily being over the eastern periphery. On 6 February, Funani was upgraded to a severe tropical storm. Under very warm waters of 30 C and excellent radial outflow, Funani entered a period of rapid intensification, presenting a sharp 12 nmi eye with tightening banding features. On 7 February, Funani peaked with 10-minute winds of 95 kn and 1-minute winds of 120 kn. On the next day, Funani initiated an eyewall replacement cycle and started to weaken. A sharp increase of wind shear caused by the upper-level westerlies then occurred and started to take a toll on Funani. While accelerating, Funani deteriorated into a severe tropical storm on 9 February. After continuous convection depletion, Funani dissipated by 12:00 UTC on the next day as a post-tropical depression.

The threat from Funani prompted officials to cancel six flights on Rodrigues.

Intense Tropical Cyclone Gelena
In addition to the pre-Funani disturbance, a circulation southeast of Agalega formed within the monsoon trough on 4 February. Drifting west-southwest, it strengthened into a tropical disturbance the next day, and then into a tropical depression. After a decrease in wind shear, the system intensified into a tropical storm on 6 February, earning the name Gelena from Météo Madagascar. Gelena formed a ragged eye and moved southeast at a slow pace. North-northwest of Port Louis, Mauritius, Gelena underwent more development as it trekked southeastward over warm waters. On 8 February, Gelena commence an eyewall replacement cycle. Upon completion, Gelena began rapidly intensifying, owing to dual outflow channels. The storm accelerated towards east, attenuating the effects of vertical wind shear. With robust deep convection surrounding the small eye, Gelena peaked on the next day, with MFR estimating winds of 110 kn and the JTWC estimating winds of 120 kn. The cyclone then weakened from wind shear and dry air after decelerating. Gelena was downgraded to a severe tropical storm by 11 February. The storm additionally weakened into a moderate tropical storm on 13 February, following the degrading of its center. As Gelena interacted with stratospheric dry air, MFR declared the storm as post-tropical on 14 February, stating that it had begun its extratropical transition. By 15 February, the storm began filling up, and dissipated on the next day.

Gelena passed by northern Madagascar around early February, bringing cumulative rainfall to over 50% above average in the north. On 8 February, the Mauritius Meteorological Services (MMS) hoisted a class I warning for the main island and Rodrigues, before upgrading it to class IV—the highest alert—two days later. Gelena struck Rodrigues on the night of 10 February, producing gusts of 160 km/h. The storm left 90% of the 40,000 inhabitants without power, while 142 sheltered in refuge centres. Fallen trees blocked roads, broke down electricity cables and phone lines. The cyclone displaced 259 people, damaged infrastructure, and private residences and farms. 43 boats were also affected, some of which could not be repaired. Overall damage on the island were about US$1 million.

Intense Tropical Cyclone Haleh
An active phase of the MJO in conjunction with equatorial wave activity led to the formation of three weak lows within the monsoon trough on the end of February, including one east of Diego Garcia. Convection stockpiled over the broad low-pressure area, as it organised over conducive conditions for development. After vorticity had increased within the system, MFR labeled it as a tropical disturbance on 1 March. The disturbance further strengthened into a tropical depression after microwave imagery had revealed a building compact center and increasing convective banding in the system. A closed eye was later detected in the intensifying cyclone, causing MFR to upgrade the system to a moderate tropical storm on the next day. As Haleh moved south-southwestward, deep convection around the centre transformed into a very cold dense overcast; accordingly, Haleh was upgraded to a tropical cyclone on 4 March.

A pronounced eye emerged on satellite imagery around a robust ring of thunderstorms, with the storm aided by diminished wind shear and strong divergence aloft. Rainbands extending towards the equator tightened into the core of the expansive system. Haleh further strengthened into an intense tropical cyclone, and peaked with 10-minute winds of 100 kn. Meanwhile, the JTWC estimated winds of 115 kn. An upper-level trough over the north and west quadrants of Haleh hampered its outflow, weakening the system. In addition, the eye of the asymmetric system became cloud-filled. Convection shifted towards the southern periphery, as the storm maintained its tropical cyclone strength on 6 March. Haleh weakened into a severe tropical storm on 7 March from a sudden surge of wind shear. Conditions increasingly became more hostile with low ocean heat, and on the next day, Haleh became post-tropical. The storm transitioned into an extratropical cyclone later that day, recurving eastward, before dissipating on 10 March.

Intense Tropical Cyclone Idai
A tropical depression formed near the Mozambican coast on 4 March. It moved north-northwest while above Mozambique, and despite land interaction, its circulation was maintained by substantial upper-level divergence and low wind shear. The disturbance then executed a counterclockwise loop and headed towards the Mozambique Channel. By 9 March, the system was re-designated a tropical depression after re-entering the sea. Later that day, it organised into a tropical storm, receiving the name Idai. Exhibiting a symmetrical eye, Idai quickly intensified into an intense tropical cyclone on 11 March as it moved southwest. An eyewall replacement cycle was then started, weakening Idai. It ended with an annular eye and Idai again reaching the intense tropical cyclone threshold. Idai attained its peak intensity on 13 March, with 10-minute winds of 105 kn and atmospheric pressure of 940 hPa. Idai made landfall at a coastline 40 km north of Beira, Mozambique on the next day. The storm rapidly weakened overland throughout 15 March, before dissipating on the following day.

As a tropical depression, Idai affected Malawi and Mozambique, during its first landfall. At least 56 people died, and 577 others were injured due to flooding in Malawi. About 83,000 people were displaced. The southern districts of Chikwawa and Nsanje became isolated by floodwaters. In Mozambique, 66 people were killed by the flooding, and affected 141,000 people. The Council of Ministers required 1.1 billion metical (US$17.6 million) to help those who were affected by the flooding. The second landfall was far more severe, and overall, Idai killed 1,593 people and left thousands more missing, becoming one of the deadliest tropical cyclones in the modern history of Africa and the Southern Hemisphere as a whole. With this death toll, Idai is the deadliest tropical cyclone recorded in the South-West Indian Ocean basin, and the second-deadliest tropical cyclone overall in the Southern Hemisphere, behind only the 1973 Flores cyclone. In addition, the total damages from the cyclone amounted to US$3.3 billion (2019 USD), which would make Idai the costliest cyclone on record in the basin.

Tropical Cyclone Savannah
On 18 March, Severe Tropical Cyclone Savannah from the Australian basin entered the South-West Indian Ocean, shortly after its peak intensity. Overnight, persistent wind shear enabled dry air entrainment to the system's core. Savannah weakened from a severe tropical storm to a moderate tropical storm on 19 March, with convective activities no longer present. The storm continued westward along a subtropical ridge to the south as intensity further decreases. By the next day, Savannah had degraded into a remnant low. During 20 March, Savannah's remnant looped eastward, before turning westward on March 21. The system weakened afterward, with Savannah's remnant dissipating on March 23.

Intense Tropical Cyclone Joaninha
The monsoon trough produced a wide circulation at the centre of the basin on 17 March, that drifted westward. It organised for several days while north-northeast of St. Brandon, and by 21 March, the MFR began releasing advisories on the system. The system was upgraded to a tropical depression on the same day, and later to Moderate Tropical Storm Joaninha. Joaninha gradually intensified from outflow and high OHC, while it attained severe tropical storm strength on 23 March and move towards the south-southwest. A ragged eye then surfaced, and Joaninha changed course to head south-southeastward, strengthening into a tropical cyclone on 24 March. Very cold cloud tops prolonged overnight, prompting the MFR to upgrade Joaninah to a intense tropical cyclone early on 25 March. Joaninha then attained its initial peak on the next day with 10-minute winds of 100 kn and 1-minute winds of 120 kn. A weakening trend then commenced, before Joaninha restrengthened, reaching a secondary peak on 27 March with the same estimates as the previous. The centre was well-defined and surrounded by annular cloud tops. However, an increase of wind shear began to weaken Joaninha. The storm fell below tropical cyclone strength on 29 March, as it continued to track over hostile environments. It then became post-tropical on 31 March, before degenerating into a remnant low on the following day. Joaninha's remnant was last noted on 4 April, and dissipated by 06:00 UTC.

Air Mauritius cancelled flights of Sir Gaetan Duval Airport on 25 March. A class IV warning was issued for Rodrigues on 26 March. As the storm approached, the Mauritius Red Cross sent fifteen volunteers to provide camp beds to the island. Joaninha made its closest approach to Rodrigues, being 80 km northeast of the island. Winds of over 100 km/h and 200 mm of rain was recorded, with the highest gust measured at 161 km/h. As 408 people sheltered in the island, Joaninha damaged electricity with its winds and obstructed roads. Being the second storm to strike Rodrigues in a year after Gelena, Joaninha destroyed 90% of the power grid on the island. Over 100 homes were damaged by the winds, with 29 being severely damaged. Four people were injured, including two women who broke their leg. 80% of plantations were destroyed, causing a significant loss of corn besides fruits. After the storm had passed, Mauritius Red Cross allocated hygiene kits, school supplies, and reconstruction materials for damaged homes, in cooperation with local emergency managers and government ministries of the county.

Intense Tropical Cyclone Kenneth
A tropical disturbance formed on 22 April. It strengthened into a tropical depression on the next day east of the Chagos Archipelago, despite moderate wind shear. As the system generally tracked westward, convection had improved within, causing the system to intensify into Moderate Tropical Storm Kenneth, and later into a severe tropical storm on the same day. An eye briefly appeared before transforming into a CDO, as wind shear weakened. Kenneth became an intense tropical cyclone on 25 April, peaking with winds of 115 kn assessed by the MFR. Rainbands spiraled around a pinhole eye, with indications of an eyewall replacement cycle. At 13:15 UTC, Kenneth made landfall in Mozambique, just north of Pemba, with 1-minute sustained winds of 220 km/h, equivalent to a Category 4 hurricane. This made Kenneth the most intense landfalling tropical cyclone in the recorded history of Mozambique. The storm rapidly weakened overland, and began to fill up on 27 April, before dissipating on the following day.

Storm names
Within the South-West Indian Ocean, tropical depressions and subtropical depressions that are judged to have 10-minute sustained windspeeds of 65 km/h by the Regional Specialised Meteorological Centre on La Réunion Island, France (RSMC La Réunion) are usually assigned a name. However, it is the Sub-Regional Tropical Cyclone Advisory centres in Mauritius and Madagascar who name the systems. The Sub-Regional Tropical Cyclone Advisory centre in Mauritius names a storm should it intensify into a moderate tropical storm between 55°E and 90°E. If instead a cyclone intensifies into a moderate tropical storm between 30°E and 55°E then the Sub-Regional Tropical Cyclone Advisory centre in Madagascar assigns the appropriate name to the storm. Storm names are taken from three pre-determined lists of names, which rotate on a triennial basis, with any names that have been used automatically removed. Therefore, all storm names used this year were later removed from the rotation and replaced with a new name for the 2021–22 season, while the unused names remained on the list.

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 (BoM) or the Meteorology, Climatology, and Geophysical Agency (BMKG). The following storms were named in this manner:

Seasonal effects
This table lists all of the tropical cyclones and subtropical cyclones that were monitored during the 2018–2019 South-West Indian Ocean cyclone season. Information on their intensity, duration, name, areas affected, primarily comes from RSMC La Réunion. Death and damage reports come from either press reports or the relevant national disaster management agency while the damage totals are given in 2018 or 2019 USD.


 * One || 14–17 September || bgcolor=#|Moderate tropical storm || bgcolor=#|40 kn || bgcolor=#|995 hPa || None || None || None ||
 * Alcide || 5–11 November || bgcolor=#|Intense tropical cyclone || bgcolor=#|100 kn || bgcolor=#|960 hPa || Agaléga, Madagascar, Tanzania || None ||  None ||
 * Bouchra || 10–20 November || bgcolor=#|Severe tropical storm || bgcolor=#|55 kn || bgcolor=#|987 hPa || None || None ||  None ||
 * Kenanga || 16–22 December || bgcolor=#|Intense tropical cyclone || bgcolor=#|100 kn || bgcolor=#|955 hPa || None || None ||  None ||
 * Cilida || 18–24 December || bgcolor=#|Intense tropical cyclone || bgcolor=#|115 kn || bgcolor=#|947 hPa || Mauritius || Minimal ||  None ||
 * Desmond || 18–22 January || bgcolor=#|Moderate tropical storm || bgcolor=#|43 kn || bgcolor=#|995 hPa || Mozambique, Madagascar || Unknown || ||
 * Eketsang || 23–25 January || bgcolor=#|Moderate tropical storm || bgcolor=#|35 kn || bgcolor=#|995 hPa || Madagascar || Unknown || ||
 * Funani || 4–9 February || bgcolor=#|Intense tropical cyclone || bgcolor=#|95 kn || bgcolor=#|943 hPa || Rodrigues || Minimal ||  None ||
 * Gelena || 5–14 February || bgcolor=#|Intense tropical cyclone || bgcolor=#|110 kn || bgcolor=#|938 hPa || Madagascar, Mauritius, Rodrigues || ||  None ||
 * Haleh || 1–7 March || bgcolor=#|Intense tropical cyclone || bgcolor=#|100 kn || bgcolor=#|943 hPa || None || None ||  None ||
 * Idai || 4–15 March || bgcolor=#|Intense tropical cyclone || bgcolor=#|100 kn || bgcolor=#|942 hPa || Mozambique, Malawi, Madagascar, Zimbabwe || ||  ||
 * Savannah || 18–19 March || bgcolor=#|Tropical cyclone || bgcolor=#|68 kn || bgcolor=#|978 hPa || None || None ||  None ||
 * Joaninha || 21–30 March || bgcolor=#|Intense tropical cyclone || bgcolor=#|100 kn || bgcolor=#|930 hPa || Rodrigues || None ||  None ||
 * Kenneth || 22–27 April || bgcolor=#|Intense tropical cyclone || bgcolor=#|115 kn || bgcolor=#|930 hPa || Seychelles, Madagascar, Comoros, Mozambique, Tanzania, Malawi || || ||
 * Lorna || 22–29 April || bgcolor=#|Tropical cyclone || bgcolor=#|80 kn || bgcolor=#|960 hPa || None || None ||  None ||
 * Funani || 4–9 February || bgcolor=#|Intense tropical cyclone || bgcolor=#|95 kn || bgcolor=#|943 hPa || Rodrigues || Minimal ||  None ||
 * Gelena || 5–14 February || bgcolor=#|Intense tropical cyclone || bgcolor=#|110 kn || bgcolor=#|938 hPa || Madagascar, Mauritius, Rodrigues || ||  None ||
 * Haleh || 1–7 March || bgcolor=#|Intense tropical cyclone || bgcolor=#|100 kn || bgcolor=#|943 hPa || None || None ||  None ||
 * Idai || 4–15 March || bgcolor=#|Intense tropical cyclone || bgcolor=#|100 kn || bgcolor=#|942 hPa || Mozambique, Malawi, Madagascar, Zimbabwe || ||  ||
 * Savannah || 18–19 March || bgcolor=#|Tropical cyclone || bgcolor=#|68 kn || bgcolor=#|978 hPa || None || None ||  None ||
 * Joaninha || 21–30 March || bgcolor=#|Intense tropical cyclone || bgcolor=#|100 kn || bgcolor=#|930 hPa || Rodrigues || None ||  None ||
 * Kenneth || 22–27 April || bgcolor=#|Intense tropical cyclone || bgcolor=#|115 kn || bgcolor=#|930 hPa || Seychelles, Madagascar, Comoros, Mozambique, Tanzania, Malawi || || ||
 * Lorna || 22–29 April || bgcolor=#|Tropical cyclone || bgcolor=#|80 kn || bgcolor=#|960 hPa || None || None ||  None ||
 * Savannah || 18–19 March || bgcolor=#|Tropical cyclone || bgcolor=#|68 kn || bgcolor=#|978 hPa || None || None ||  None ||
 * Joaninha || 21–30 March || bgcolor=#|Intense tropical cyclone || bgcolor=#|100 kn || bgcolor=#|930 hPa || Rodrigues || None ||  None ||
 * Kenneth || 22–27 April || bgcolor=#|Intense tropical cyclone || bgcolor=#|115 kn || bgcolor=#|930 hPa || Seychelles, Madagascar, Comoros, Mozambique, Tanzania, Malawi || || ||
 * Lorna || 22–29 April || bgcolor=#|Tropical cyclone || bgcolor=#|80 kn || bgcolor=#|960 hPa || None || None ||  None ||
 * Kenneth || 22–27 April || bgcolor=#|Intense tropical cyclone || bgcolor=#|115 kn || bgcolor=#|930 hPa || Seychelles, Madagascar, Comoros, Mozambique, Tanzania, Malawi || || ||
 * Lorna || 22–29 April || bgcolor=#|Tropical cyclone || bgcolor=#|80 kn || bgcolor=#|960 hPa || None || None ||  None ||
 * Lorna || 22–29 April || bgcolor=#|Tropical cyclone || bgcolor=#|80 kn || bgcolor=#|960 hPa || None || None ||  None ||