2015–16 South Pacific cyclone season

The 2015–16 South Pacific cyclone season was one of the most disastrous South Pacific tropical cyclone seasons on record, with a total of 50 deaths and $1.405 billion (2016 USD) in damage. Throughout the season, 8 systems attained tropical cyclone status, whilst 5 became severe tropical cyclones. The most notable cyclone of the season by far was Winston, which attained a minimum pressure of 884 hPa (mbar; 26.10 inHg), and maximum ten-minute sustained winds of 175 mph, making it the most intense tropical cyclone on record in the Southern Hemisphere. Winston went on to devastate Fiji, causing $1.4 billion (2016 USD) in damage and 44 deaths across the country.

The 2015–16 season marked the period of the year when most tropical cyclones form within the South Pacific Ocean to the east of 160°E. The season officially ran from November 1, 2015, to April 30, 2016, however a tropical cyclone could form at any time between July 1, 2015, and June 30, 2016, and would count towards the season total. During the season, tropical cyclones are officially monitored by the Fiji Meteorological Service and the Meteorological Service of New Zealand (MetService). Other warning centres like the Australian Bureau of Meteorology and the United States Joint Typhoon Warning Center (JTWC) will also monitor the basin. The FMS and MetService both use the Australian Tropical Cyclone Intensity Scale and estimate wind speeds over a period of ten minutes, while the JTWC estimated sustained winds over a 1-minute period, which are subsequently compared to the Saffir–Simpson hurricane wind scale (SSHWS).

Seasonal forecasts
After the occurrences of Tropical Cyclone Raquel and Tropical Depression 01F during July and August 2015, the Fiji Meteorological Service (FMS) noted that the ongoing 2014–16 El Niño event, might mean that more tropical cyclones occur in the basin than usual during the season. It was also noted that during previous El Niño episodes the season started early, with systems developing before the start of the season on November 1. As a result, the FMS expected the tropical cyclone season to start during October 2015. During September 24, Météo-France announced that there was a 90% chance of either a moderate tropical storm, severe tropical storm or tropical cyclone, impacting the waters surrounding French Polynesia during the season. Ahead of the cyclone season, the FMS, the BoM, Météo-France, New Zealand's MetService and National Institute of Water and Atmospheric Research (NIWA) and various other Pacific Meteorological services, all contributed towards the Island Climate Update tropical cyclone outlook that was released during October 2015.

The outlook took into account the strong El Niño conditions that had been observed across the Pacific and analogue seasons that had ENSO neutral and weak El Niño conditions occurring during the season. The outlook called for an above average number of tropical cyclones for the 2015–16 season, with eleven to thirteen named tropical cyclones to occur between 135°E and 120°W compared to an average of 10–12. At least six of the tropical cyclones were expected to become category 3 severe tropical cyclones, while four could become category 4 severe tropical cyclones. It was also noted that Category 5 severe tropical cyclones, with 10-minute sustained windspeeds of 196 km/h were known to occur during El Niño events. In addition to contributing towards the Island Climate Update outlook the BoM and the FMS, issued their own seasonal forecasts for the South Pacific region. The BoM issued a seasonal forecast for both the Western and Eastern South Pacific. The Western region between 142.5°E and 165°E was predicted to have a 15% chance of having an above average number of tropical cyclones, while the Eastern region between 165°E and 120°W was predicted to have a 48% chance of having an above average number of tropical cyclones. Within their outlook the FMS predicted that between ten and fourteen tropical cyclones, would occur within the basin compared to an average of around 7.3 cyclones. Between four and eight of these tropical cyclones were expected to intensify into category 3 severe tropical cyclones, while 3-7 might intensify into Category 4 or 5 severe tropical cyclones. They also reported that the tropical cyclone genesis trough was expected to be displaced far eastwards of its long term average position. This was based on the expected and predicted ENSO conditions, and the existence of the Pacific warm pool of sub-surface temperature anomalies in this region.

Both the Island Climate Update and the FMS tropical cyclone outlooks assessed the risk of a tropical cyclone affecting a certain island or territory. As the tropical cyclone genesis trough of low pressure was expected to be located near to and to the east of the International Date Line, normal or slightly above normal activity was expected for areas near the dateline. With the exception of Kiribati, Papua New Guinea, New Caledonia, Niue, and Tonga, the Island Climate Update predicted that all areas would experience an elevated risk of being affected by multiple tropical cyclones. The FMS's outlook predicted that the Solomon and Northern Cook Islands, Wallis and Futuna, Tokelau, Samoa, and French Polynesia had a highly elevated chance of being affected by a tropical cyclone. Vanuatu, Fiji, Niue, and the Southern Cook Islands had an elevated risk, while a normal risk was anticipated for New Caledonia, Tuvalu, and Tonga.

Tropical Depression 01F
The first tropical depression of the season was first noted as a tropical disturbance during July 29, while it was located about 920 km to the north-northeast of Honiara in the Solomon Islands. The system lay to the north of an upper level subtropical ridge of high pressure in an area of moderate vertical wind shear. Over the next couple of days the system slowly organised further as it steered south-eastwards into an area of decreasing vertical wind shear.

Tropical Depression 02F
During October 12, Tropical Disturbance 02F developed along the South Pacific convergence zone, while it was located about 450 km to the northwest of Rotuma. The system was located within a favourable environment for further development, with low to moderate vertical wind shear, and it lay under an upper-level ridge of high pressure.

Tropical Cyclone Tuni
On November 23, Tropical Disturbance 03F developed within a trough of low pressure, about 500 km to the northeast of Suva, Fiji. The system lay in an area of low to moderate vertical wind shear, to the south of an upper-level ridge of high pressure.

Across American Samoa, Tuni produced strong winds and heavy rains. Sustained winds of 56 mph were observed in Tututila at an elevated location. Some trees were uprooted. Plantations, shacks, and garages sustained damage with total losses amounting to US$5 million. There was no significant damage recorded in Niue, as the system brushed the island nation.

Severe Tropical Cyclone Ula
In late December 2015, a long-lived and powerful westerly wind burst triggered the formation of a tropical disturbance in the south Pacific, along with its twin in the central North Pacific, which became Tropical Depression Nine-C.

Tropical Depression 07F
Three people died in seagoing accidents related to Tropical Depression 07F, while four others went missing.

Severe Tropical Cyclone Victor
On January 10, the FMS reported that Tropical Disturbance 08F had developed about 100 km to the northwest of Penrhyn in the Northern Cook Islands. A few days later, the system was classified as an invest, until JTWC classified it with a low-chance of developing to a tropical cyclone on January 13. Later in that same day, 08F was upgraded to a tropical depression. On January 14, the JTWC issued a TCFA alert as 08F was located in moderate wind shear and warm sea-surface temperatures, which were conductive for tropical development. Hours later, the JTWC upgraded 08F to a tropical cyclone as it was designated as 07P and started issuing advisories, located 368 mi east of Pago Pago, American Samoa. On January 15, 08F was upgraded to a Category 1 tropical cyclone and was therefore named Victor.

Severe Tropical Cyclone Winston
Tropical Disturbance 09F developed on February 7, 2016, to the northwest of Port Vila, Vanuatu. Over the next few days, the system gradually developed as it moved southeastward, acquiring gale-force winds by February 11. The following day it underwent rapid intensification and attained ten-minute maximum sustained winds of 175 km/h. Less favourable environmental conditions prompted weakening thereafter. After turning northeast on February 14, Winston stalled to the north of Tonga on February 17. Regaining strength, the storm doubled back to the west, achieving Category 5 status on both the Australian tropical cyclone scale and the Saffir–Simpson hurricane wind scale on February 19. It reached its record intensity the next day with ten-minute sustained winds of 280 km/h and a pressure of 884 hPa (mbar; 26.10 inHg), shortly before making landfall on Viti Levu, Fiji. This made it the strongest storm to ever strike the nation, as well as the strongest tropical cyclone of the Southern Hemisphere in history.

On February 26, Winston exited the South Pacific basin and entered the Australian region basin.

In advance of the storm's arrival in Fiji, numerous shelters were opened, and a nationwide curfew was instituted during the evening of February 20. Striking Fiji at Category 5 intensity on February 20, Winston inflicted extensive damage on many islands and killed at least 44 people. Communications were temporarily lost with at least six islands. Total damage from Winston amounted to $FJ 2.98 billion ($1.4 billion 2016 USD), making it the costliest cyclone on record in the basin.

Tropical Cyclone Tatiana
Tropical Cyclone Tatiana moved into the South Pacific basin from the Australian region during February 12, as it peaked as a Category 2 tropical cyclone with 10-minute sustained winds of 95 km/h (60 mph). The system subsequently moved southwards and rapidly weakened during the next day, crossing back into BoM's area of responsibility. On the next day it degenerated into a remnant low.

Tropical Cyclone Yalo
During February 23, Tropical Disturbance 11F developed underneath an upper-level ridge of high pressure, about 850 km to the northwest of Tahiti, French Polynesia. By the next day, the JTWC issued a Tropical Cyclone Formation Alert as it was located over in favorable conditions of developing further.

Severe Tropical Cyclone Zena
Severe Tropical Cyclone Zena passed near Fiji. This storm interfered with Survivor, causing the contestants to be temporarily evacuated on day 2.

Severe Tropical Cyclone Amos
Tropical Disturbance 17F was first noted on April 13, while it was located about 130 km to the northwest of the Fijian dependency of Rotuma.

Other systems
As the 2015–16 tropical cyclone year opened on July 1, Tropical Cyclone Raquel was located in the Australian region to the north-west of Honiara. Over the next 24 hours, the system recurved eastwards and weakened into a tropical depression, as it entered the basin on July 2. The system subsequently moved westwards and out of the basin during July 4, as it impacted the Solomon Islands, with high wind gusts and heavy rain. Tropical Disturbance 04F was first noted on December 1, while it was located about 640 km to the northeast of Papeete in French Polynesia. Over the next day the poorly organised system moved westwards, underneath an upper-level ridge of high pressure before it dissipated during December 2. During December 27, Tropical Disturbance 06F developed to the north of Wallis Island, in an area of moderate to high vertical wind shear.

During February 29, Tropical Disturbance 12F developed about 330 km, to the northwest of Papeete on the island of Tahiti in French Polynesia. However, during that day as the system moved southwards in an area of low vertical wind shear, atmospheric convection decreased in magnitude before it was last noted during March 1. Tropical Disturbance 13F was first noted on March 19, about 500 km to the northwest of Nouméa in New Caledonia. Over the next couple of days the system moved east-southeast, before it was last noted during March 21, to the southeast of New Caledonia.

On April 2, Tropical Disturbance 14F formed from an active monsoon trough over Vanuatu. The system moved in a slow eastward motion over in an area of favorable environments, thus, RSMC Nadi forecast the system to reach tropical cyclone intensity. During April 5, 14F began to weaken with a lack of further organisation and therefore, RSMC Nadi issued its final bulletin later that day. In the same time when 14F was formed, RSMC Nadi had reported of the formation of Tropical Disturbance 15F just to the east of Fiji. Again, 15F was located over in favorable environments with deep convection and a developing LLCC. During April 4, the JTWC issued a TCFA on the system, however it was also mentioned that organization started to weaken. 15F passed Fiji and rapidly diminished on April 6. During April 20, Tropical Disturbance 18F developed within an area of low to moderate vertical wind-shear, to the south of an upper-level ridge of high pressure to the north of the Southern Cook Islands.

Storm names
Within the Southern Pacific a tropical depression is judged to have reached tropical cyclone intensity should it reach winds of 65 km/h and it is evident that gales are occurring at least halfway around the center. Tropical depressions that intensify into a tropical cyclone between the Equator and 25°S and between 160°E and 120°W are named by the FMS. However, should a tropical depression intensify to the south of 25°S between 160°E and 120°W it will be named by MetService in conjunction with the FMS. If a tropical cyclone moves out of the basin and into the Australian region, it will retain its original name. The names Tuni, Ula, Victor, Winston, Yalo, Zena and Amos would be used for the first (and only, in the case of Ula, Winston, Yalo and Zena) time this year, after replacing the names Tui, Ursula, Veli, Wes, Yali, Zuman and Alan after the 1997-98 season. The names that were used for the 2015-16 season are listed below:

If a tropical cyclone enters the South Pacific basin from the Australian region basin (west of 160°E), it will retain the name assigned to it by the Australian Bureau of Meteorology. The following storms were named in this manner:


 * Tatiana

Retirement
After the season, the names Ula, Winston, Yalo and Zena were all retired, and replaced with Ulu, Wanita, Yates and Zidane respectively.

Season effects
This table lists all the storms that developed in the South Pacific to the east of longitude 160°E during the 2015–16 season. It includes their intensity on the Australian tropical cyclone intensity scale, duration, name, landfalls, deaths, and damages. All data is taken from RSMC Nadi and/or TCWC Wellington, and all of the damage figures are in 2015 USD.


 * 01F || July 29 – August 4 || bgcolor=#|Tropical depression || bgcolor=#|Not specified || bgcolor=#|1000 hPa || Solomon Islands, Vanuatu || None || None ||
 * 02F || October 12–18 || bgcolor=#|Tropical depression || bgcolor=#|45 km/h || bgcolor=#|1001 hPa || Vanuatu || None || None ||
 * Tuni || November 26–30 || bgcolor=#|Category 1 tropical cyclone || bgcolor=#|75 km/h || bgcolor=#|992 hPa || Tuvalu, Samoan Islands, Niue, Tonga ||  || None ||
 * 04F || December 1–2 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|1003 hPa || French Polynesia || None || None ||
 * Ula || December 26 – January 12 || bgcolor=#|Category 4 severe tropical cyclone || bgcolor=#|185 km/h || bgcolor=#|944 hPa || Tuvalu, Samoan Islands, Tonga, Fiji, Vanuatu, New Caledonia || Minimal || ||
 * 06F || December 27–30 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|997 hPa || Wallis and Futuna || None || None ||
 * 07F || December 28 – January 1 || bgcolor=#|Tropical depression || bgcolor=#|Not specified || bgcolor=#|995 hPa || Solomon Islands, Tuvalu, Fiji || None || ||
 * Victor || January 14–22 || bgcolor=#|Category 3 severe tropical cyclone || bgcolor=#|150 km/h || bgcolor=#|958 hPa || Northern Cook Islands, Niue, Tonga || None || None ||
 * Winston || February 7–26 || bgcolor=#|Category 5 severe tropical cyclone || bgcolor=#|280 km/h || bgcolor=#|884 hPa || Vanuatu, Fiji, Tonga, Niue || || 44 ||
 * Tatiana || February 12–13 || bgcolor=#|Category 2 tropical cyclone || bgcolor=#|95 km/h || bgcolor=#|983 hPa || None || None || None ||
 * Yalo || February 24–26 || bgcolor=#|Category 1 tropical cyclone || bgcolor=#|75 km/h || bgcolor=#|993 hPa || Cook Islands, French Polynesia || None || None ||
 * 12F || February 29 – March 1 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|1000 hPa || French Polynesia || None || None ||
 * 13F || March 19–22 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|998 hPa || New Caledonia, Vanuatu || None || None ||
 * 14F || April 1–5 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|1002 hPa || Vanuatu || None || None ||
 * 15F || April 2–6 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|998 hPa || Fiji || Minor || None ||
 * Zena || April 5–7 || bgcolor=#|Category 3 severe tropical cyclone || bgcolor=#|130 km/h || bgcolor=#|975 hPa || Solomon Islands, Vanuatu, Fiji, Tonga || Minimal || 2 ||
 * Amos || April 20–24 || bgcolor=#|Category 3 severe tropical cyclone || bgcolor=#|150 km/h || bgcolor=#|965 hPa || Fiji, Wallis and Futuna, Samoan Islands || Minimal || None ||
 * 18F || April 20–27 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|1002 hPa || French Polynesia || None || None ||
 * Tatiana || February 12–13 || bgcolor=#|Category 2 tropical cyclone || bgcolor=#|95 km/h || bgcolor=#|983 hPa || None || None || None ||
 * Yalo || February 24–26 || bgcolor=#|Category 1 tropical cyclone || bgcolor=#|75 km/h || bgcolor=#|993 hPa || Cook Islands, French Polynesia || None || None ||
 * 12F || February 29 – March 1 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|1000 hPa || French Polynesia || None || None ||
 * 13F || March 19–22 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|998 hPa || New Caledonia, Vanuatu || None || None ||
 * 14F || April 1–5 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|1002 hPa || Vanuatu || None || None ||
 * 15F || April 2–6 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|998 hPa || Fiji || Minor || None ||
 * Zena || April 5–7 || bgcolor=#|Category 3 severe tropical cyclone || bgcolor=#|130 km/h || bgcolor=#|975 hPa || Solomon Islands, Vanuatu, Fiji, Tonga || Minimal || 2 ||
 * Amos || April 20–24 || bgcolor=#|Category 3 severe tropical cyclone || bgcolor=#|150 km/h || bgcolor=#|965 hPa || Fiji, Wallis and Futuna, Samoan Islands || Minimal || None ||
 * 18F || April 20–27 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|1002 hPa || French Polynesia || None || None ||
 * 14F || April 1–5 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|1002 hPa || Vanuatu || None || None ||
 * 15F || April 2–6 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|998 hPa || Fiji || Minor || None ||
 * Zena || April 5–7 || bgcolor=#|Category 3 severe tropical cyclone || bgcolor=#|130 km/h || bgcolor=#|975 hPa || Solomon Islands, Vanuatu, Fiji, Tonga || Minimal || 2 ||
 * Amos || April 20–24 || bgcolor=#|Category 3 severe tropical cyclone || bgcolor=#|150 km/h || bgcolor=#|965 hPa || Fiji, Wallis and Futuna, Samoan Islands || Minimal || None ||
 * 18F || April 20–27 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|1002 hPa || French Polynesia || None || None ||
 * Amos || April 20–24 || bgcolor=#|Category 3 severe tropical cyclone || bgcolor=#|150 km/h || bgcolor=#|965 hPa || Fiji, Wallis and Futuna, Samoan Islands || Minimal || None ||
 * 18F || April 20–27 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|1002 hPa || French Polynesia || None || None ||
 * 18F || April 20–27 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|1002 hPa || French Polynesia || None || None ||
 * 18F || April 20–27 || bgcolor=#|Tropical disturbance || bgcolor=#|Not specified || bgcolor=#|1002 hPa || French Polynesia || None || None ||