2018–19 South-West Indian Ocean cyclone season

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2018–19 South-West Indian Ocean cyclone season
2018-2019 South-West Indian Ocean cyclone season summary.png
Season summary map
Seasonal boundaries
First system formedSeptember 13, 2018
Last system dissipatedCurrently active
Strongest storm
NameAlcide
 • Maximum winds165 km/h (105 mph)
(10-minute sustained)
 • Lowest pressure965 hPa (mbar)
Seasonal statistics
Total disturbances3
Total depressions3
Total storms3
Tropical cyclones1
Intense tropical cyclones1
Total fatalitiesNone
Total damageNone
Related articles
South-West Indian Ocean tropical cyclone seasons
2016–17, 2017–18, 2018–19, 2019–20, 2020–21

The 2018–19 South-West Indian Ocean cyclone season is an ongoing event of the annual cycle of tropical cyclone and subtropical cyclone formation. It officially began on November 15, 2018, and will end on April 30, 2019, with the exception for Mauritius and the Seychelles, for which it will end on May 15, 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.

Seasonal summary[edit]

Tropical cyclone scales#Comparisons across basins

Systems[edit]

Moderate Tropical Storm 01[edit]

Moderate tropical storm (MFR)
Tropical storm (SSHWS)
01R 2018-09-16 0920Z.jpg 01R 2018 track.png
DurationSeptember 13 – September 17
Peak intensity75 km/h (45 mph) (10-min)  1004 hPa (mbar)

On September 13, a tropical depression (tropical storm on the SSHWS scale) formed to the southwest of Diego Garcia.[1] The system tracked west-southwestward, organizing slowly over marginally waters of 26–27 degrees Celsius and moderate wind shear.[2] On September 16, the tropical depression began to weaken, after encountering unfavorable conditions. On September 17, MFR and the JTWC issued their final warnings, and the system dissipated.[3] In post-storm analysis, the system was upgraded into a moderate tropical storm; however, the system was not named.[4]

Intense Tropical Cyclone Alcide[edit]

Intense tropical cyclone (MFR)
Category 3 tropical cyclone (SSHWS)
Alcide 2018-11-08 0656Z.jpg Alcide 2018 track.png
DurationNovember 5 – November 11
Peak intensity165 km/h (105 mph) (10-min)  965 hPa (mbar)

On November 6, a tropical depression formed well to the east-northeast of Madagascar.[5] The system continued to track generally west-southwestward into more favorable conditions for the next few hours, before strengthening into Moderate Tropical Storm Alcide later that day.[6] On November 7 at 06:00 UTC, Alcide strengthened into a tropical cyclone.[7] On November 8 at 06:00 UTC, Alcide strengthened into an intense tropical cyclone, with maximum 10-minute sustained winds of 90 knots (165 km/h; 105 mph).[8] It was downgraded to a tropical cyclone 6 hours later, however, due to cooler sea temperatures and generally less favorable conditions.[9] Alcide continued to weaken as it began an anticyclonic loop east of the northern tip of Madagascar, falling to tropical storm status at 12:00 UTC on November 9.[10] The system rapidly deteriorated thereafter, falling to tropical depression status at 0:00 UTC on November 11; Meteo-France discontinued advisories at noon that day.[11][12]

Severe Tropical Storm Bouchra[edit]

Severe tropical storm (MFR)
Tropical storm (SSHWS)
Bouchra 2018-11-11 0650Z.jpg Bouchra 2018 track.png
DurationNovember 9 – November 19
(Out of basin from November 9 to 10, from November 12 to 13, and from November 14 to 16)
Peak intensity95 km/h (60 mph) (10-min)  990 hPa (mbar)

A weak low-pressure system developed in the equatorial Indian Ocean in Météo-France's area of responsibility on 1 November and moved slowly eastwards over the following few days while showing little sign of intensification.[13] Late on 9 November, as the developing precursor depression to Cyclonic Storm Gaja in the Bay of Bengal moved further away and the competing low-level airflow convergence associated with it diminished,[14] the system's structure organised sufficiently to be classified as a tropical disturbance by Météo-France.[15] 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 10 November local time.[16] 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.[17] A few hours later, at 10:00 UTC, the system moved back westwards and returned to the South-West Indian Ocean basin,[18] where it gained the name 'Bouchra' from Météo-France and underwent a twelve-hour phase of rapid intensification to severe tropical storm status.[19]

Over the following days, Bouchra fought increasingly unfavourable atmospheric conditions, and underwent a gradual weakening trend.[20] 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.[20] After meandering here for a number of days, the system re-entered the Australian region late on 12 November.[21] By this stage, the system had weakened significantly from its peak intensity, and was only at tropical depression strength.[22] 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 13 November.[21] In the early hours of November 14, the Australian Bureau of Meteorology noted that the system had crossed back into the Australian region.[23]

Storm names[edit]

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 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 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 Center in Madagascar assigns the appropriate name to the storm. Beginning from the 2016–17 season, name lists within the South-West Indian Ocean will be rotated on a triennial basis. Storm names are only used once, so any storm name used this year will be removed from rotation and replaced with a new name for the 2021–22 season. The unused names are expected to be reused in the list for the 2021–22 season.[24]

  • Alcide
  • Bouchra
  • Cilida (unused)
  • Desmond (unused)
  • Eketsang (unused)
  • Funani (unused)
  • Gelena (unused)
  • Haleh (unused)
  • Idai (unused)
  • Joaninha (unused)
  • Kenneth (unused)
  • Lorna (unused)
  • Maipelo (unused)
  • Njazi (unused)
  • Oscar (unused)
  • Pamela (unused)
  • Quentin (unused)
  • Rajab (unused)
  • Savana (unused)
  • Themba (unused)
  • Uyapo (unused)
  • Viviane (unused)
  • Walter (unused)
  • Xangy (unused)
  • Yemurai (unused)
  • Zanele (unused)

Seasonal effects[edit]

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.

Name Dates active Peak classification Sustained
wind speeds
Pressure Areas affected Damage
(USD)
Deaths Refs
01 September 13 – 17 Moderate tropical storm 75 km/h (45 mph) 1004 hPa (29.65 inHg) None None None
Alcide November 5 – 11 Intense tropical cyclone 165 km/h (105 mph) 965 hPa (28.50 inHg) Agaléga, Madagascar None None
Bouchra November 9 – 19 Severe tropical storm 95 km/h (60 mph) 990 hPa (29.23 inHg) None None None
Season aggregates
3 systems September 13 – Present 165 km/h (105 mph) 965 hPa (28.50 inHg) None None


See also[edit]

References[edit]

  1. ^ http://www.meteo.fr/temps/domtom/La_Reunion/webcmrs9.0/francais/activiteope/bulletins/cmrs/CMRSF_201809140600_1_1_20182019.pdf (in French)
  2. ^ http://www.meteo.fr/temps/domtom/La_Reunion/webcmrs9.0/francais/activiteope/bulletins/cmrs/CMRSF_201809150600_3_1_20182019.pdf (in French)
  3. ^ http://www.meteo.fr/temps/domtom/La_Reunion/webcmrs9.0/francais/activiteope/bulletins/cmrs/CMRSF_201809170600_7_1_20182019.pdf (in French)
  4. ^ "Saisons cycloniques archivées: Tempête Tropicale Modérée 01" (in French). Météo-France. 2018. Retrieved November 8, 2018.
  5. ^ http://www.meteo.fr/temps/domtom/La_Reunion/webcmrs9.0/francais/activiteope/bulletins/cmrs/CMRSF_201811060600_1_2_20182019.pdf (in French)
  6. ^ http://www.meteo.fr/temps/domtom/La_Reunion/webcmrs9.0/francais/activiteope/bulletins/cmrs/CMRSF_201811061800_ALCIDE.pdf (in French)
  7. ^ http://www.meteo.fr/temps/domtom/La_Reunion/webcmrs9.0/francais/activiteope/bulletins/cmrs/CMRSF_201811070600_ALCIDE.pdf (in French)
  8. ^ http://www.meteo.fr/temps/domtom/La_Reunion/webcmrs9.0/francais/activiteope/bulletins/cmrs/CMRSF_201811080600_ALCIDE.pdf (in French)
  9. ^ http://www.meteo.fr/temps/domtom/La_Reunion/webcmrs9.0/francais/activiteope/bulletins/cmrs/CMRSF_201811081200_ALCIDE.pdf (in French)
  10. ^ http://www.meteo.fr/temps/domtom/La_Reunion/webcmrs9.0/francais/activiteope/bulletins/cmrs/CMRSF_201811091200_ALCIDE.pdf (in French)
  11. ^ http://www.meteo.fr/temps/domtom/La_Reunion/webcmrs9.0/francais/activiteope/bulletins/cmrs/CMRSF_201811110000_EX-ALCIDE.pdf (in French)
  12. ^ http://www.meteo.fr/temps/domtom/La_Reunion/webcmrs9.0/francais/activiteope/bulletins/cmrs/CMRSF_201811111200_EX-ALCIDE.pdf (in French)
  13. ^ "12 UTC Gradient Level Wind Analysis Chart". Bureau of Meteorology. 1 November 2018.
  14. ^ "Tropical Activity Bulletin" (PDF). Météo-France La Réunion. 9 November 2018.
  15. ^ "Moderate Tropical Storm Bouchra Forecast Track Map". Météo-France La Réunion. 10 November 2018. Archived from the original on 11 November 2018.
  16. ^ "Current Tropical Cyclone Basin Activity". Meteorology, Climatology and Geophysical Agency. 10 November 2018. Archived from the original on 10 November 2018.
  17. ^ "Tropical Cyclone 04S Warning #1". Joint Typhoon Warning Center. 10 November 2018. Archived from the original on 10 November 2018.
  18. ^ "Tropical Activity Bulletin" (PDF). Météo-France La Réunion. 10 November 2018.
  19. ^ "Bouchra Analysis Bulletin #2" (PDF). Météo-France La Réunion. 11 November 2018.
  20. ^ a b "Tropical Storm Bouchra Advisory (12 UTC)" (PDF). Météo-France La Réunion. 11 November 2018. Retrieved 14 November 2018.
  21. ^ a b "Tropical Activity Bulletin" (PDF). Météo-France La Réunion. 13 November 2018. Retrieved 13 November 2018.
  22. ^ "Western Region Tropical Cyclone Outlook". Bureau of Meteorology. 13 November 2018. Archived from the original on 13 November 2018. Retrieved 13 November 2018.
  23. ^ "Western Region Tropical Cyclone Outlook". Bureau of Meteorology. 14 November 2018. Archived from the original on 14 November 2018. Retrieved 14 November 2018.
  24. ^ Regional Association I Tropical Cyclone Committee (2016). "Tropical Cyclone Operational Plan for the South-West Indian Ocean" (PDF). World Meteorological Organization. Retrieved 2016-10-05.

External links[edit]