The 2012–13 South-West Indian Ocean cyclone season was a slightly above average event in

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. Depend ...

formation in the Southern hemisphere tropical cyclone year starting on July 1, 2012, and ending on June 30, 2013. Within this basin, tropical and subtropical disturbances are officially 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 p ...

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 ...

island, while the Mauritius and Madagascar weather services assign names to significant tropical and subtropical disturbances. The first tropical disturbance of the season developed on October 12 and rapidly developed into the earliest known intense tropical cyclone on record during October 14. __TOC__

Seasonal summary

ImageSize = width:800 height:200 PlotArea = top:10 bottom:80 right:20 left:20 Legend = columns:3 left:30 top:58 columnwidth:250 AlignBars = early DateFormat = dd/mm/yyyy Period = from:01/10/2012 till:01/06/2013 TimeAxis = orientation:horizontal ScaleMinor = grid:black unit:month increment:1 start:01/10/2012 Colors = id:canvas value:gray(0.88) id:GP value:red id:ZD value:rgb(0.5,0.8,1) legend:Zone_of_Disturbed_Weather/Tropical_Disturbance id:TD value:rgb(0.38,0.73,1) legend:Tropical_Depression/Subtropical_Depression id:TS value:rgb(0,0.98,0.96) legend:Moderate_Tropical_Storm id:ST value:rgb(0.80,1,1) legend:Severe_Tropical_Storm id:TC value:rgb(1,1,0.80) legend:Tropical_Cyclone id:IT value:rgb(1,0.76,0.25) legend:Intense_Tropical_Cyclone id:VI value:rgb(1,0.38,0.38) legend:Very_Intense_Tropical_Cyclone Backgroundcolors = canvas:canvas BarData = barset:Hurricane bar:Month PlotData= barset:Hurricane width:11 align:left fontsize:S shift:(4,-4) anchor:till from:12/10/2012 till:19/10/2012 color:IT text:"Anais (ITC)" from:15/11/2012 till:16/11/2012 color:ZD text:"02 (TDi)" from:23/11/2012 till:26/11/2012 color:ST text:"Boldwin (STS)" from:06/12/2012 till:13/12/2012 color:IT text:"Claudia (ITC)" from:29/12/2012 till:05/01/2013 color:TC text:"Dumile (TC)" from:12/01/2013 till:18/01/2013 color:TS text:"Emang (MTS)" barset:Break from:26/01/2013 till:03/02/2013 color:IT text:"Felleng (ITC)" from:11/02/2013 till:15/02/2013 color:TC text:"Gino (TC)" from:18/02/2013 till:23/02/2013 color:TC text:" Haruna (TC)" from:05/04/2013 till:16/04/2013 color:TC text:"Imelda (TC)" from:09/05/2013 till:11/05/2013 color:TS text:"Jamala (MTS)" bar:Month width:5 align:center fontsize:S shift:(0,-20) anchor:middle color:canvas from:01/10/2012 till:31/10/2012 text:October from:01/11/2012 till:30/11/2012 text:November from:01/12/2012 till:31/12/2012 text:December from:01/01/2013 till:01/02/2013 text:January from:01/02/2013 till:01/03/2013 text:February from:01/03/2013 till:01/04/2013 text:March from:01/04/2013 till:01/05/2013 text:April from:01/05/2013 till:01/06/2013 text:May TextData = pos:(525,23) text:"(For further details, please see" pos:(672,23) text:"

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 w ...

The first tropical disturbance of the season developed on October 12 and gradually intensified to become the earliest known intense tropical cyclone on record on October 14.

Systems

Intense Tropical Cyclone Anais

On October 12, 2012, 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 forming ...

(TCFA) on a system near the

Chagos Islands The Chagos Archipelago () or Chagos Islands (formerly the Bassas de Chagas, and later the Oil Islands) is a group of seven atolls comprising more than 60 islands in the Indian Ocean about 500 kilometres (310 mi) south of the Maldives archi ...

. Soon afterwards, RSMC La Réunion designated the system as a tropical disturbance while located roughly to the west of

Diego Garcia Diego Garcia is an island of the British Indian Ocean Territory, a disputed overseas territory of the United Kingdom. It is a militarised atoll just south of the equator in the central Indian Ocean, and the largest of the 60 small islands o ...

. That afternoon, the JTWC upgraded the system into a tropical depression, giving it the designation ''01S''. The next day, RSMC La Réunion reported that the system had intensified into a moderate tropical storm and named it ''Anais''. As the day progressed, Anais began a period of quick intensification—being upgraded into a tropical cyclone by RSMC La Réunion and a category one tropical cyclone by the JTWC. Late on October 15, as it started to weaken, the system's eye started to collapse, but deep convection remained over the low level circulation center, and it was downgraded to a category 1 cyclone by October 16. On October 17, the system weakened into a tropical storm, and the low-level circulation center became totally exposed, with convection being displaced to the south due to moderate vertical wind shear from the north west. As the day progressed, Anais weakened into a tropical depression. On October 14, Anais became the earliest intense tropical cyclone in the South-West Indian Ocean.

Tropical Disturbance 02

On November 8, an area of low pressure formed far northeast of La Réunion. It gradually drifted west and developed a low-level circulation center (LLCC). On the next day, isolated convection developed around the system with fragmented spiral banding. The low drifted southwest and slightly weakened on November 12. The low-pressure area soon became disorganized and the JTWC stopped tracking it later that day. Early on November 15, the disturbance regained strength and the convective banding around its LLCC improved and JTWC resumed tracking the system. At the same time, RSMC La Réunion upgraded the low-pressure area to a tropical disturbance. The next day, the system lost most of its convection and Météo France stopped tracking the disturbance, reporting that their forecast models showed no chance of the system restrengthening.

Severe Tropical Storm Boldwin

On November 23, the system organized under moderate vertical wind shear, and the Météo-France started to track the system as a tropical disturbance By midnight, that day, Météo-France further upgraded the system to a tropical depression. In the early hours of November 24, RSMC La Réunion further upgraded the tropical depression into a Moderate Tropical Storm with Mauritius assigning it the name Boldwin. Later the same day, the JTWC also started tracking the system as Tropical Cyclone 02S with winds equivalent to a tropical storm on the SSHS, while it developed an eye-like feature. During the afternoon, Météo-France further upgraded Boldwin into a Severe Tropical Storm with 10-minute sustained winds reaching . On November 25, the storm encountered strong vertical wind shear and much of its convection got displaced to the southeast, partially exposing the center. That day, Boldwin weakened into a Moderate Tropical Storm. Later that night, Boldwin's LLCC became fully exposed and started weakening rapidly. As a result, the JTWC issued their final advisory on the system. At the same time, Météo-France reported that Boldwin further weakened into a Tropical Depression. Finally, during the early hours of November 26, Météo-France issued their final warning on Boldwin, as it weakened into a remnant low, as moderate vertical wind shear had torn the system apart.

Intense Tropical Cyclone Claudia

The disturbance moved south-westwards over the following week, strengthening as

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 horizontal ...

decreased. On 6 December, JTWC issued a TCFA and RSMC La Réunion commenced advisories for a Tropical Disturbance. The disturbance was then located about 900 km (550 miles) SE of

. The next day it was named Moderate Tropical Storm Claudia by NWS Mauritius. On December 8, Cyclone Claudia was in South Indian Ocean and had strengthened rapidly with winds over . On December 10, a well-developed eye was observed, with diameter of approximately 19 km (12 mi). By December 11, Claudia's eye had dissipated, and the cyclone became more disorganized, with wind shear causing elongation from east to west. Claudia moved into sea surface temperatures below , as a result of the western edge of a high pressure ridge steering the system south. On December 12, high vertical wind shear near 30 knots (55.5 km/h; 34.5 mph) impacted the northwestern quadrant of the low level circulation center, exposing the center, as it became extratropical over cooler waters. On December 13, the system became fully extratropical, with the low level circulation center becoming fully exposed, and convection displaced far south of the circulation center by strong vertical wind shear.

Tropical Cyclone Dumile

On December 28 a low-pressure area continued to organize, with a significant increase in convection, located just to the west of an

anticyclone An anticyclone is a weather phenomenon defined as a large-scale circulation of winds around a central region of high atmospheric pressure, clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere as viewed from abov ...

. In Mauritius, the storm produced winds up to that downed trees and power lines. Transportation across the region was several disrupted as public transit was shut down and many roads were blocked by debris. In Cassis, a billboard collapsed and damaged a nearby home. One person was found dead after his body washed ashore in Flic-en-Flac. In addition to winds, the storm brought heavy rains to the region, amounting to in Arnaud. Overall, damage from the storm was fairly limited in Mauritius. Cyclone Dumile produced strong winds across Réunion Island, peaking at , that downed numerous trees and power lines, leaving approximately 125,000 residents without electricity. Downed wires also led to the death of one person after he tried to remove a live wire from the roof of his home. Additionally 14 people were injured by the storm. Heavy rains also affected much of the island, with falling in Cirad over a 24‑hour span. These rains proved to be mostly beneficial, restoring reservoirs and replenishing rivers, as the island experienced below-average rainfall in the preceding two months. Significant agricultural damage took place on the island, with losses reaching

€ The euro sign () is the currency sign used for the euro, the official currency of the eurozone and unilaterally adopted by Kosovo and Montenegro. The design was presented to the public by the European Commission on 12 December 1996. It consists o ...

31 million (US$41.3 million). Insured losses were estimated at €3.5 million (US$4.7 million).

Moderate Tropical Storm Emang

By December 28, the JTWC began tracking the system, as it began to make a significant increase in deep convection, with formative convective banding developing around the system. At that time, the disturbance was located west of an upper-level anticyclone and directly beneath a subtropical ridge center, in an area of light vertical wind shear, north-northwest of Learmonth, Australia. On December 30, the low-level circulation center became partially exposed due to moderate to strong easterly moving vertical wind shear, while the western part of the system still had deep, persistent convection. By January 17, Emang became disorganized and weakened into a small area of flaring convection. The low-level circulation center had become weak and poorly defined, due to moderate vertical wind shear.

Intense Tropical Cyclone Felleng

On January 18, an elongated, poorly organized area of

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 convec ...

associated with the remnants of Tropical Storm Emang lingered near the ITCZ. By January 24, RSMC La Réunion reported a totally exposed vortex with occasional burst of convection persisted about NNE of

Rodrigues Rodrigues (french: Île Rodrigues, link=yes ; Creole: ) is a autonomous outer island of the Republic of Mauritius in the Indian Ocean, about east of Mauritius. It is part of the Mascarene Islands, which include Mauritius and Réunion. Rodr ...

, and SW of

. At that time it was not expected to strengthen, but early on 26 January, convective activity improved, with deep convection and redeveloped a well defined, partially exposed low level circulation center due to moderate vertical wind shear from the East, and was designated as a Tropical Depression. It continued to strengthen as it moved west, then south-west as it steadily intensified, reaching Intense Tropical Cyclone strength on 30 January while developing a well defined eye, with a deep, intense ring of convective banding forming in the eyewall. On January 31 the eye became less well defined, and started to collapse. On February 1 the system started to become elongated, and weakened into a severe tropical storm as it began its extratropical transition. By February 3, 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. Although the center of Cyclone Felleng remained offshore, heavy rain from the storm's outer bands triggered significant flooding in parts of Madagascar. Flood waters 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 alone. 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 flood waters, 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 Fito ...

. Heavy rains and winds associated with the storm also impacted Réunion Island, where 11,200 homes were left without power. Over the course of three days, 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 during a 24‑hour span.

Tropical Cyclone Gino

On 11 February, RSMC La Réunion announced that a Tropical Depression had formed about ESE of

. The disturbance had first been noticed several days earlier as a Tropical Low in the Australian AoR. It was soon upgraded and named Moderate Tropical Storm Gino. On 12 February at 1500 UTC, the storm's maximum sustained winds was making the storm the equivalent of a category one hurricane. At that time, Gino was centered near 17.1 south latitude and 79.5 east longitude, about southeast of

. Gino moved south-southwest at , around the northwestern edge of a

subtropical ridge The horse latitudes are the latitudes about 30 degrees north and south of the Equator. They are characterized by sunny skies, calm winds, and very little precipitation. They are also known as Subtropics, subtropical ridges, or highs. It is a h ...

of high pressure.

Tropical Cyclone Haruna

In the middle of February, an area of convection persisted in the Mozambique Channel. The system shifted southward after exiting the coast of Mozambique and slowed to a drift in response to a break in the

. Subsequently, convection became more pronounced and Météo France classified the system as a tropical disturbance on February 18. On February 19, the system attained gale-force winds and was upgraded to Moderate Tropical Storm Haruna. The structure of Haruna continued to become more symmetrical with a large

radius of maximum wind The radius of maximum wind (RMW) is the distance between the center of a cyclone and its band of strongest winds. It is a parameter in atmospheric dynamics and tropical cyclone forecasting. The highest rainfall rates occur near the RMW of tropic ...

s, developing a ragged

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 ...

early on February 20. Based on the improved appearance, MFR upgraded Haruna to a severe tropical storm at 0000 UTC that day. About 12 hours later, the agency upgraded Haruna further to tropical cyclone status, with 10 minute winds of . That day, an approaching

trough Trough may refer to: In science * Trough (geology), a long depression less steep than a trench * Trough (meteorology), an elongated region of low atmospheric pressure * Trough (physics), the lowest point on a wave * Trough level (medicine), the l ...

weakened the ridge to the south, causing the cyclone to slow and move erratically. MFR assessed that Haruna reached 10 minute winds of on February 20. At around 0230 UTC on February 22, the cyclone 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 ...

about 55 km (35 mi) south of

Morombe Morombe is an urban municipality (commune urbaine) on the south-west coast in Atsimo-Andrefana, Madagascar. It can be reached by the National road 55 or pirogue from Morondava. It is situated at 283 km from Tulear. An airport serves the town. ...

in southwestern Madagascar. Haruna quickly weakened below cyclone status, and while over land it accelerated to the southeast. At 1200 UTC on February 24, MFR issued its last advisory after Haruna began losing tropical characteristics, designating it as a

subtropical depression A subtropical cyclone is a weather system that has some characteristics of both tropical and an extratropical cyclone. As early as the 1950s, meteorologists were uncertain whether they should be characterized as tropical or extratropical cyclon ...

. The next day, the JTWC also discontinued advisories on the storm, noting that Haruna was dissipating about 665 km (415 mi) south-southwest of

. Striking the southwestern coast of Madagascar, Cyclone Haruna impacted areas that usually do not see tropical cyclones. The most significant damage took place north of

Toliara Toliara (also known as ''Toliary'', ; formerly ''Tuléar'') is a city in Madagascar. It is the capital of the Atsimo-Andrefana region, located 936 km southwest of national capital Antananarivo. The current spelling of the name was adopted ...

around the

Mikea Forest The Mikea Forest (or Forêt des Mikea) is a forested region of southwestern Madagascar, between Manombo and Morombe. More specifically, it stretches from Route Nationale 9 to the west coast and from Mangoky south to the Manombo River. It lies at ...

. The storm brought wind gusts estimated at , resulting in extensive damage. Many homes lost their roofs and numerous roads were blocked by debris, isolating communities. Several days of heavy rain caused extensive flooding, especially in

where approximately 70 percent of the city was destroyed due to flash flooding and dam collapses. In nearby Toliara, dozens of people were evacuated due to similarly dangerous flooding. At least 24 people were killed across southern Madagascar and another 16 were listed as missing. In addition, at least 92 were injured and nearly 10,000 left homeless after the passage of Haruna.

Tropical Cyclone Imelda

On April 3, the Joint Typhoon Warning Center started tracking an area of weak, shallow convection located around a low-level circulation center (LLCC) near 8.5°S 75.6°E. By April 4, the system developed flaring convection around a consolidating, partially exposed LLCC. On April 5, the system developed convective bands that have further deepened, and wrapped tighter around the LLCC. Later that day, the RSMC designated the system Zone of Disturbed Weather 10.

Moderate Tropical Storm Jamala

In the middle of May, Tropical Storm Jamala existed in the northeastern portion of the basin.

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, (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 p ...

on La Réunion Island, France (RSMC La Réunion) are usually assigned a name. However it is the Sub-Regional Tropical Cyclone Advisory Centers in Mauritius and Madagascar who name the systems. The Sub-Regional Tropical Cyclone Advisory Center in Mauritius names the storm should it intensify into a moderate tropical storm between 55°E and

90°E The meridian 90° east of Prime Meridian, Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, Asia, the Indian Ocean, the Southern Ocean, and Antarctica to the South Pole. It is the border between two trop ...

, if the storm should intensify into a moderate tropical storm between 30°E and 55°E then the Sub-Regional Tropical Cyclone Advisory Center in Madagascar assigns the appropriate name to the storm. New name lists are used every year, whilst a name is normally only used once so thus far no names are retired. For the first time this year tropical cyclones that move into this region from the Australian Region will not be renamed by the Sub-Regional Tropical Cyclone Advisory Center in Mauritius.

Season effects

This table lists all of the tropical cyclones and subtropical cyclones that were monitored during the 2012–2013 South-West Indian Ocean cyclone season. Information on their intensity, duration, name, and areas affected, primarily comes from RSMC La Réunion.Météo France (RSMC La Réunion)
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References

{{DEFAULTSORT:2012-13 South-West Indian Ocean cyclone season 2012 in Madagascar 2013 in Madagascar 2012 in Réunion 2013 in Réunion Articles which contain graphical timelines South-West Indian Ocean cyclone seasons 2012 SWIO 2013 SWIO