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 and unofficially by the Joint Typhoon Warning Center.
[1] 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 having environmental conditions more conducive for cyclogenesis.
Alvaro became a tropical depression the next day, traversing the Mozambique Channel, before making landfall in Morombe District, Madagascar on 1 January 2024.
[9] 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.
[13] 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.
[18] By 29 December, a monsoon trough had produced convection southeast of Beira, Mozambique that spun, as convergence of winds increased within the system's closed surface circulation.
[28] On 11 January, the MFR marked a zone of disturbed weather, citing the conducive conditions induced by the MJO and an equatorial Rossby wave.
[29] By the next day, the JTWC issued a Tropical Cyclone Formation Alert (TCFA) on the potential disturbance, since it was in an environment of very warm sea surface temperatures, high ocean heat content, low vertical shear, and excellent outflow.
Additionally, microwave imagery indicated an eye in the lower-layer while the storm steered more westward,[31] and the JTWC began issuing advisories on the system as a tropical cyclone.
[33] Intense lightning activity within the center further signaled a period of rapid intensification, leading to Belal becoming a severe tropical storm.
"[50] On 17 January, the MFR noted in its daily bulletin that a strong surge of monsoon flow northeast of the Mascarenes could produce a precursor vortex.
[52] Upper-level divergence in conjunction with warm sea surface temperatures subdued the effects of vertical shear, enabling consolidation of the disturbance.
[58] 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 95 km/h (60 mph).
[63] 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 −112 °F (−80 °C) cloud tops.
[72][73] 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.
[82] 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.
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.
[94] As the eye 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.
[96] Soon afterward, the storm structure evolved the eye pattern and was surrounded by intense convective bursts, becoming a tropical cyclone.
[11] 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.
[12] Rain accumulations were estimated by weather satellite to be of the order of 130 mm in 24 hours, approximately the normal rainfall for the entire month of March.
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.
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.
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.
Satellite imagery shows that it began rapidly eroding, with its convective activity diminished, and the cloud tops considerably warmed.
[120] On 13 May, the Joint Typhoon Warning Center began monitoring a low-level circulation which persisted 588 nm east-northeast of Comoros, stating it was in a favourable environment to intensify.
[131] 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.
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.
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 on Réunion island, France (RSMC La Réunion) are usually assigned a name by the Sub-Regional Tropical Cyclone Advisory Centers in Mauritius and Madagascar.