2018–19 South Pacific cyclone season
The 2018–19 South Pacific cyclone season was a below-average season that produced 5 tropical cyclones, 2 of which became severe tropical cyclones. The season officially runs from November 1, 2018, to April 30, 2019; however, a tropical cyclone could have formed at any time between July 1, 2018, and June 30, 2019, and would count towards the season total. During the season, tropical cyclones were officially monitored by the Fiji Meteorological Service, Australian Bureau of Meteorology, and New Zealand's MetService. The United States Armed Forces through the Joint Typhoon Warning Center also monitored the basin and issued warnings for American interests. RSMC Nadi attaches a number and an F suffix to 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 FMS, the BoM 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 formally starting, 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 2018. The outlook took into account the ENSO neutral conditions that had been observed across the Pacific and analogue seasons that had ENSO neutral and El Niño conditions occurring during the season. The outlook called for a near-average number of tropical cyclones for the 2018–19 season, with seven to eleven named tropical cyclones, predicted 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 intensify further and become severe tropical cyclones, while it was noted that a Category 5 severe tropical cyclone could 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 seven and nine tropical cyclones, would occur within the basin compared to an average of around 7.1 cyclones. At least two of the tropical cyclones were expected to intensify further and become Category 3 or higher severe tropical cyclones.
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 the Austral Islands, American Samoa, the Cook Islands and Samoa had an elevated chance, while the Northern Cook Islands had a normal to elevated chance of being impacted by a tropical cyclone. They also predicted that Fiji, Niue, Papua New Guinea, Tonga, Tokelau, Tuvalu, Wallis and Futuna, the Society and the Solomon Islands all had a near-normal risk of being impacted. The outlook noted that Vanuatu and New Caledonia had a normal to reduced risk of being impacted by multiple tropical cyclones while it was considered unlikely that the Pitcairn Islands, Kiribati and parts of French Polynesia such as the Marquesas Islands and the Tuamotu Archipelago would be impacted by a tropical cyclone. The FMS's outlook predicted that Tuvalu, Wallis and Futuna, Tokelau, Samoa, Niue, the Cook, Society and Austral Islands had an increased chance of being impacted by a tropical cyclone. Their outlook also predicted that the Solomon Islands, Vanuatu, Fiji, Tonga, the Pitcairn Islands and Tuamotu Archipelago and the Gambier Islands had a normal chance of being impacted by a tropical cyclone. It was also noted that New Caledonia had a reduced chance of being affected by a tropical cyclone, while tropical cyclone activity near Kiribati and the Marquesas Islands was considered unlikely. It was thought by the FMS that there was an increased risk of Wallis & Futuna, the Cook, Society and the Austral Islands being impacted by at least one severe tropical cyclone, while other areas such as Fiji, New Caledonia, Niue, the Solomon Islands, Tokelau, Samoa, Tonga and Niue had a normal to reduced chance of being impacted by a severe tropical cyclone.
Seasonal summary
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Systems
Tropical Cyclone Liua
A disturbance which initially formed in the Australian region basin crossed into the South Pacific basin on September 26 and strengthened, and was designated as Tropical Depression 01F by RSMC Nadi. Late on September 26, the storm intensified into a tropical cyclone, and was given the name Liua. Liua is the earliest-forming named tropical cyclone in the South Pacific basin since reliable records began, surpassing Cyclone Lusi in 1997.Tropical Disturbance 02F
During November 11, the FMS reported that Tropical Disturbance 02F had developed about to the north-northeast of Honiara in the Solomon Islands. At this stage the system was located within an area of low vertical windshear, while deep convection surrounding the system's low level circulation was poorly organised. Over the next few days, the system's organization slightly improved as it moved south-eastwards before it was last noted on November 16, while located about to the northeast of Port Vila in Vanuatu.Tropical Depression 03F
During December 28, the FMS reported that Tropical Disturbance 03F had developed within a trough of low pressure, about to the east of Honiara in the Solomon Islands. The disturbance was located within a favourable environment for further development to the south of an upper-level ridge, while deep atmospheric convection persisted over the systems elongated low-level circulation. During the next day, as the organisation of the system improved, the FMS relocated the system to be located near the Solomon Island of San Cristobal. The system subsequently moved eastwards through Temotu Province and gradually developed further, before it was classified as a tropical depression during December 30. It dissipated on January 1.Tropical Cyclone Mona
Mona entered this basin as a tropical low from the Australian region basin. The system then intensified into Tropical Depression 04F on January 3. Later that day, it intensified into a Category 1 cyclone on the Australian scale and was named Mona. It peaked as a Category 2 tropical cyclone. On January 7, the system dissipated.About 2,000 people took shelter in 40 evacuation centers over the weekend, and thirty roads were closed, mostly due to floods and some landslides. People in the Lau group have been warned to expect gale-force and heavy rain as Mona tracked south, before arching south-west over Fiji over the next 24 hours.