2017–18 South Pacific cyclone season
The 2017–18 South Pacific cyclone season was a slightly below-average season that produced 6 tropical cyclones, 3 of which became severe tropical cyclones. The season officially began on November 1, 2017 and ended on April 30, 2018; however, a tropical cyclone could form at any time between July 1, 2017 and June 30, 2018 and would count towards the season total. During the season, tropical cyclones were officially monitored by the Fiji Meteorological Service, MetService and the Australian Bureau of Meteorology, while the United States Joint Typhoon Warning Center also monitored the basin and issued warnings for American interests. The FMS attaches a number and an F suffix to significant tropical disturbances that form in or move into the basin, while the JTWC designates significant tropical cyclones with a number and a P suffix. The BoM, FMS and MetService all use the Australian Tropical Cyclone Intensity Scale and estimate wind speeds over a period of ten minutes, while the JTWC estimates sustained winds over a 1-minute period, which are subsequently compared to the Saffir–Simpson hurricane wind scale.
Seasonal forecasts
Ahead of the cyclone season, the Fiji Meteorological Service, Australian Bureau of Meteorology, New Zealand's MetService and National Institute of Water and Atmospheric Research and various other Pacific Meteorological services, all contributed towards the Island Climate Update tropical cyclone outlook that was released during October 2016. The outlook took into account the ENSO neutral conditions that had been observed across the Pacific and analogue seasons that had ENSO neutral and weak La Nina conditions occurring during the season. The outlook called for a near average number of tropical cyclones for the 2017–18 season, with eight to ten named tropical cyclones, to occur between 135°E and 120°W compared to an average of about 10. At least three of the tropical cyclones were expected to become Category 3 severe tropical cyclones, while two could become Category 4 severe tropical cyclones; they also noted that a Category 5 severe tropical cyclone was not likely to occur during the season.In addition to contributing towards the Island Climate Update outlook, the FMS and the BoM issued their own seasonal forecasts for the South Pacific region. The BoM issued two seasonal forecasts for the Southern Pacific Ocean, for their self-defined eastern and western regions of the South Pacific Ocean. They predicted that the Western region between 142.5°E and 165°E, had a 48% chance of seeing activity above its average of 7 tropical cyclones. The BoM also predicted that the Eastern Region between 165°E and 120°W, had a 55% chance of seeing activity above its average of 4 tropical cyclones. Within their outlook the FMS predicted that between four and six tropical cyclones, would occur within the basin compared to an average of around 7.1 cyclones. At least one of the tropical cyclones was expected to intensify into a Category 3 or higher severe tropical cyclone. They also predicted that the main area for tropical cyclogenesis would be within the Coral Sea, to the west of the International Dateline.
Both the Island Climate Update and the FMS tropical cyclone outlooks assessed the risk of a tropical cyclone affecting a certain island or territory. The Island Climate Update Outlook predicted that New Caledonia, Tonga, New Zealand and Papua New Guinea had an above average chance of being impacted by a tropical cyclone or their remnants. They also predicted that the Solomon Islands, Fiji and Vanuatu had a near normal to normal risk of being impacted by one or more tropical cyclones. The Southern Cook Islands, American Samoa, Samoa, Niue, Tokelau, Tuvalu, as well as Wallis and Futuna were thought to have a below average chance of being impacted. It was also considered unlikely that the Northern Cook Islands, French Polynesia, Kiribati and the Pitcairn Islands would be affected by a tropical cyclone. The FMS's outlook predicted that Vanuatu, New Caledonia, Fiji as well as Wallis and Futuna had a normal chance of being impacted by a tropical cyclone. The outlook also predicted that the Solomon Islands, Tokelau, Samoa, Tonga, Niue, Cook Islands and French Polynesia had a reduced chance of being affected by a tropical cyclone. It was thought that there was a normal risk of Vanuatu, New Caledonia, Fiji and Samoa being impacted by at least one severe tropical cyclone, while other areas such as the Solomon Islands, Tokelau, Samoa, Tonga, Niue and French Polynesia, had a reduced chance of being impacted by a severe tropical cyclone.
Seasonal summary
ImageSize = width:800 height:200
PlotArea = top:10 bottom:80 right:20 left:20
Legend = columns:3 left:30 top:58 columnwidth:270
AlignBars = early
DateFormat = dd/mm/yyyy
Period = from:01/12/2017 till:01/06/2018
TimeAxis = orientation:horizontal
ScaleMinor = grid:black unit:month increment:1 start:01/12/2017
Colors =
id:canvas value:gray
id:GP value:red
id:TDi value:rgb legend:Tropical_Disturbance
id:TD value:rgb legend:Tropical_Depression
id:C1 value:rgb legend:Category_1_=_63-87_km/h_
id:C2 value:rgb legend:Category_2_=_88-142_km/h_
id:C3 value:rgb legend:Category_3_=_143-158-km/h_
id:C4 value:rgb legend:Category_4_=_159–204_km/h_
id:C5 value:rgb legend:Category_5_=_≥205_km/h_
Backgroundcolors = canvas:canvas
BarData =
barset:Hurricane
bar:Month
PlotData=
barset:Hurricane width:11 align:left fontsize:S shift: anchor:till
from:16/12/2017 till:18/12/2017 color:TDi text:"02F "
from:17/12/2017 till:19/12/2017 color:TDi text:"03F "
from:20/12/2017 till:26/12/2017 color:TD text:"04F "
from:26/01/2018 till:27/01/2018 color:TDi text:"05F "
from:28/01/2018 till:30/01/2018 color:C1 text:"Fehi "
from:03/02/2018 till:19/02/2018 color:C5 text:"Gita "
from:03/02/2018 till:11/02/2018 color:TD text:"08F "
barset:break
from:03/03/2018 till:11/03/2018 color:C4 text:"Hola "
from:11/03/2018 till:13/03/2018 color:TD text:"Linda "
from:20/03/2018 till:24/03/2018 color:C1 text:"Iris "
from:29/03/2018 till:02/04/2018 color:C1 text:"Josie "
from:05/04/2018 till:11/04/2018 color:C3 text:"Keni "
from:17/04/2018 till:20/04/2018 color:TD text:"14F "
from:04/05/2018 till:09/05/2018 color:C1 text:"Lexi "
bar:Month width:5 align:center fontsize:S shift: anchor:middle color:canvas
from:01/12/2017 till:01/01/2018 text:December
from:01/01/2018 till:01/02/2018 text:January
from:01/02/2018 till:01/03/2018 text:February
from:01/03/2018 till:01/04/2018 text:March
from:01/04/2018 till:01/05/2018 text:April
from:01/05/2018 till:01/06/2018 text:May
TextData =
pos:
text:""
Systems
Tropical Depression 04F
Tropical Disturbance 05F
Tropical Cyclone Fehi
Insurance loss were amounted at NZ$38.5 million.Severe Tropical Cyclone Gita
Tropical Depression 08F
Severe Tropical Cyclone Hola
During March 3, 2018 the Fiji Meteorological Service reported that Tropical Disturbance 09F had developed within a trough of low pressure about to the northeast of Nadi, Fiji. At this time the disturbance had a broad low-level circulation and was located within a very favourable environment for further development, with low vertical wind shear and warm sea surface temperatures. Over the next couple of days, the disturbance gradually developed further as it gradually moved westwards towards Vanuatu, under the influence of a subtropical ridge of high pressure. It was subsequently classified as a tropical depression by the FMS during March 5, before the United States Joint Typhoon Warning Center subsequently issued a tropical cyclone formation alert on the system later that day.During March 6, the JTWC initiated advisories on the system and designated it as Tropical Cyclone 12P, after its broad low-level circulation center had slowly consolidated and the overall organisation of the cyclone had improved. The FMS subsequently reported that the system had developed into a Category 1 tropical cyclone on the Australian tropical cyclone intensity scale and named it Hola, while it was located about to the east of Pentecost Island in Vanuatu. After it was named, Hola started developing a weak low level eye feature, before it was classified as a category 2 tropical cyclone as it passed in between the islands of Pentecost and Ambrym. The system subsequently passed over the island of Malekula and moved into the Coral Sea during March 7, where it rapidly consolidated and developed a pinhole eye. The FMS subsequently reported that Hola had become a Category 4 Severe Tropical Cyclone and predicted that Hola would peak as a Category 5 Severe Tropical Cyclone.
Tropical Depression 10F (Linda)
On March 11, the FMS reported that Tropical Disturbance 10F, had developed about to the southwest of Rennell and Bellona Province of the Solomon Islands. The system was poorly organised with deep atmospheric convection, displaced to the east of the system's consolidating low-level circulation center. The disturbance was subsequently classified as Tropical Low 21U by the BoM during March 12, as it moved southwards within an area of low vertical wind shear and warm sea surface temperatures.Tropical Cyclone Iris
During March 20, the FMS reported that Tropical Disturbance 11F had developed within an area of low to moderate vertical wind shear, over the eastern Solomon Islands around to the east of Honiara. At this time the system was poorly organised with deep atmospheric convection, located to the east of the low-level circulation centre. Over the next few days, the system remained weak as it moved erratically around the Solomon Islands and was classified as a tropical depression during March 22.Tropical Cyclone Josie
Despite not making landfall, Tropical Cyclone Josie caused heavy rainfall and sustained gale-force winds in southern Fiji. Severe flooding occurred in the city of Nadi, and at least five people were washed away by floodwaters, of which four are confirmed dead and one is still missing.Severe Tropical Cyclone Keni
Tropical Cyclone Keni impacted Fiji and caused the cast and crew of the of the American reality competition series, Survivor, to be temporarily evacuated to the production's base camp.Tropical Depression 14F
Other systems
During December 16, Tropical Disturbance 02F developed within a trough of low pressure, about to the northeast of the island of Futuna. During the following day, Tropical Disturbance 03F developed along the same trough of low pressure about to the southeast of the island of Wallis. Over the next couple of days, the disturbances moved southeastwards into areas of high vertical wind shear, before they were last noted during December 18 and 19 as they dissipated to the southeast of Samoa.On January 28, the JTWC issued a tropical cyclone formation alert on a tropical disturbance, which was located near the French Polynesian island of Rapa Iti. The system had a well defined low-level circulation, and was located within an area of warm sea surface temperatures and marginal vertical wind shear. The system subsequently peaked with 1-minute sustained wind speeds of, which made it equivalent to a tropical storm. The alert was subsequently cancelled during the next day, after the system's low level circulation center became ragged, while atmospheric convection was displaced to the east of the circulation center.
On May 4, 2018, a system identified as a subtropical cyclone formed east of 120°W, just a few hundred miles off the coast of Chile, with researchers unofficially naming the storm Lexi. The cyclone formed in an area without a Regional Specialized Meteorological Center, so it was not officially classified. On May 9, the satellite services division of the NOAA classified the system as a weak subtropical storm, despite occurring in cooler sea surface temperatures.