2015–16 South-West Indian Ocean cyclone season

Severe tropical storm (MFR)
Tropical storm (SSHWS)
Duration	November 19 – November 23
Peak intensity	100 km/h (65 mph) (10-min); 983 hPa (mbar)

Météo-France first noted a zone of disturbed weather about 930 km (580 mi) east-northeast of Diego Garcia on November 18. It was designated as a tropical disturbance the next day, and upgraded to a tropical depression shortly thereafter.[4] On November 20, the system's organization continued to improve with tight convective banding and it was upgraded to moderate tropical storm status about 270 km (170 mi) south of Diego Garcia.[12] The system was not named Annabelle operationally until early the next day.[13] Annabelle intensified slowly for several days as it drifted south-southeast.[4] The system accelerated to the southeast and developed an eye feature.[14] Annabelle became a severe tropical storm early on November 23,[4] benefiting from strong upper level divergence aloft.[14] Six hours later, Annabelle reached its peak intensity of 100 km/h (65 mph).[4] By November 24, Annabelle's convection became disorganized as a result of increased wind shear induced by an upper level trough and cooler ocean temperatures and it was declared post-tropical.[15] The remnants of Annabelle weakened in the following days until it dissipated during November 27.[4]

Moderate tropical storm (MFR)
Tropical storm (SSHWS)
Duration	December 9 – December 12
Peak intensity	65 km/h (40 mph) (10-min); 995 hPa (mbar)

On December 3, a disorganized area of convection developed over the equatorial regions of the central Indian Ocean.[16] The system tracked generally southwest until it intensified into Tropical Depression 02 on December 10.[5] The tropical depression gradually turned to the south-southwest and exhibited weak convection, leaving the system exposed as it struggled to intensify within a dry air mass.[17] It received the name Bohale from the Mauritius Meteorological Services early on December 11 when it was operationally determined to have become a moderate tropical storm.[18] In post-season re-analysis, Météo-France determined that Bohale became a tropical storm a day later, on December 12.[5] Bohale maintained its peak intensity of 65 km/h (40 mph) as a moderate tropical storm for 18 hours, before transitioning into a post-tropical depression at 18 UTC while retaining its gale-force winds.[5] The post-tropical remnants of Bohale tracked south slowly until they dissipated on December 16.[5]

Severe tropical storm (MFR)
Category 1 tropical cyclone (SSHWS)
Duration	January 20 – January 24
Peak intensity	110 km/h (70 mph) (10-min); 975 hPa (mbar)

Météo-France identified a tropical disturbance moving generally westward over the eastern Indian Ocean on January 20.[6] At midday the next day, the disturbance intensified into a moderate tropical storm which received the name Corentin.[6] Corentin continued to steadily intensify under an upper-level ridge as its motion began to turn towards the south.[19] The system was upgraded to severe tropical storm status on January 22 as it tracked nearly due south.[6] Corentin peaked later that day with 10-minute maximum sustained wind speeds of 110 km/h (70 mph) and a large, 110 km (70 mi) ragged eye.[20] The system began to weaken on January 23 as its satellite representation deteriorated and its eye began to widen.[21] The storm continued to weaken as the upper-level wind pattern became unfavorable.[22] With its center exposed and moving over cooler waters,[23] Corentin transitioned into a post-tropical depression on January 24. The post-tropical remnants of Corentin meandered in the southern Indian Ocean until its remnant low dissipated on January 31.[6]

Moderate tropical storm (MFR)
Tropical storm (SSHWS)
Duration	February 8 – February 12
Peak intensity	65 km/h (40 mph) (10-min); 990 hPa (mbar)

A low-pressure area developed within a monsoon trough over the Mozambique Channel on February 1.[24] It tracked southeastward, crossing Madagascar and becoming a tropical disturbance 380 km (235 mi) north of Saint-Denis, Réunion on February 8.[7] The disturbance began to travel generally southwestward, intensifying slowly. The next day, the system turned southeast under the influence of a ridge to its east and a cut-off low to the southwest.[25] On February 11, the system was classified as Moderate Tropical Storm Daya, while located about 545 km (340 mi) south-southwest of Saint-Denis.[7] Daya accelerated to the southeast under the influence of the ridge and favorable poleward divergence allowed the system to peak with maximum sustained winds of 65 km/h (40 mph) early the next day.[25][7] Daya quickly met strong wind shear, which led to its transition into a post-tropical depression on February 12.[26] Météo-France ceased monitoring post-tropical Daya the following day.[7]

Between February 9 and 10, heavy rain from Daya affected parts of Madagascar, Réunion, and Mauritius. During a 24-hour period, 111 mm (4.4 in) of rain fell in Vacoas-Phoenix, Mauritius, and 100 mm (3.9 in) fell in Saint-Denis, Réunion. Flash flooding damaged homes and displaced hundreds of people in Mauritius.[27]

Intense tropical cyclone (MFR)
Category 4 tropical cyclone (SSHWS)
Duration	February 14 (Entered basin) – February 19
Peak intensity	205 km/h (125 mph) (10-min); 925 hPa (mbar)

Uriah entered the South-West Indian Ocean basin as a moderate tropical storm from the Australian region on February 14, where it was previously monitored by the Bureau of Meteorology's office in Perth.[8] The storm tracked generally southwest, maintaining intensity.[8] Early on February 16, Uriah began to intensify steadily, turning to the west as a subtropical ridge built in to the south of the system. Uriah also began to develop an eye, which became evident later that day.[28] On February 17, Uriah attained hurricane-force (74 mph or 118 km/h) winds, becoming the first tropical cyclone of the season.[8] Continuing to rapidly intensify, Uriah became an intense tropical cyclone twelve hours later. As the ridge previously located to the south of Uriah rebuilt to its east, the intense tropical cyclone began to turn to the south.[29] As northwesterly wind shear began to affect the system, its appearance began to deteriorate and its convection lessened.[30] Uriah rapidly weakened to a severe tropical storm by February 19, and it transitioned to a post-tropical depression shortly thereafter. Uriah's remnants meandered, nearly stationary in the southern Indian Ocean, until it became an extratropical depression and raced to the southeast.[8]

Intense tropical cyclone (MFR)
Category 4 tropical cyclone (SSHWS)
Duration	March 15 – March 21
Peak intensity	205 km/h (125 mph) (10-min); 940 hPa (mbar)

Moderate Tropical Storm Emeraude developed near the eastern periphery of the basin on March 15.[9] With favorable environmental conditions and a good poleward outflow channel, the storm rapidly intensified[31] into a tropical cyclone the next day.[9] The small cyclone tracked slowly toward the west-northwest, continuing to strengthen rapidly.[32] It became an intense tropical cyclone early on March 17, reaching peak sustained wind speeds of 205 km/h (125 mph).[9] Under the influence of a strengthening near equatorial ridge located to its northeast, Emeraude's motion began to slow and turn to the east.[33] The cyclone was quickly affected by increasing wind shear and decreased oceanic heat content induced by its slow movement, resulting in significant weakening.[34] Unable to reach favorable conditions, Emeraude weakened below tropical cyclone intensity by 0600 UTC on March 18, 24 hours after reaching peak intensity.[9] The system briefly weakened into a moderate tropical storm before restrengthening early the next day once it reached warmer waters.[35] Emeraude turned to the south and approached tropical cyclone strength on March 19, but remained a severe tropical storm.[9] Conditions became unfavorable yet again and wind shear increased, pushing convection away from the system's center, allowing for weakening to occur once again.[36] Emeraude ceased to produce gale-force winds and became a tropical depression on March 21. Its remnant low dissipated on March 23 just south of the waters where it had reached peak intensity five days prior.[9]

Moderate tropical storm (MFR)
Tropical storm (SSHWS)
Duration	March 28 – March 30
Peak intensity	85 km/h (50 mph) (10-min); 993 hPa (mbar)

A tropical disturbance formed in the central Indian Ocean, 770 km (480 mi) south-southeast of Diego Garcia on March 28.[10] The disturbance intensified into a tropical depression and was pushed quickly to the southeast ahead of a trough, away from the British Indian Ocean Territory. Having been previously analyzed as a tropical depression throughout its lifetime, Météo-France noted that 07 intensified into a moderate tropical storm the same day.[10] Moderate Tropical Storm 07 briefly attained peak maximum sustained winds of 85 km/h (50 mph) the next day before strong wind shear pummelled the system,[37] resulting in swift weakening and a prompt transition into a post-tropical depression on March 30.[10]

Very intense tropical cyclone (MFR)
Category 5 tropical cyclone (SSHWS)
Duration	April 11 – April 23
Peak intensity	250 km/h (155 mph) (10-min); 910 hPa (mbar)

Fantala formed on April 11 to the south of Diego Garcia.[38] With a ridge to the south, the storm moved westward for several days while gaining strength, aided by warm waters and decreasing wind shear.[39][40] Late on April 17, the MFR estimated peak 10-minute sustained winds of 250 km/h (155 mph), the highest on record in the basin.[41] Meanwhile, the JTWC estimated peak 1-minute sustained winds of 285 km/h (180 mph), surpassing Cyclone Agnielle from November 1995 as the strongest cyclone on record in the south-west Indian Ocean in terms of wind speed. The system weakened due to an eyewall replacement cycle, and a change of steering currents caused Fantala to reverse direction and accelerate southeast. This brought the cyclone over cooler waters previously upwelled by itself, causing further weakening. Between April 19 and 23, Fantala fluctuated in intensity. At first, the eye became more pronounced,[42] but wind shear soon caused weakening to resume. By April 22, Fantala stalled again due to a building ridge to its south. Fantala accelerated back northwest as a moderate tropical cyclone, with the JTWC and MFR issuing their final advisories on April 24. The remnants of Fantala continued northwest toward the East African coast.

Evacuations were initiated on Agaléga ahead of Cyclone Fantala.[43] While near peak intensity, the cyclone also passed near the Farquhar Group of the Seychelles, damaging most of the buildings in the small archipelago.[44] The islands were declared a disaster area by Seychelles officials.[44] After dissipation, Fantala's remnant moisture affected Tanzania and Kenya, where heavy rains and flooding killed 13 people and left 13,933 homeless.[45] Eight people were killed in the Kilimanjaro Region where flooding entered buildings and trapped hundreds of residents.[45] In the Morogoro Region, five people drowned in flooded rivers.[46]