The 1997–98 South Pacific cyclone season was the most active South Pacific tropical cyclone season on record, with 16 tropical cyclones occurring within the South Pacific basin between 160°E and 120°W. The season started earlier than normal with 3 systems developing before the official start of the season on November 1, 1997, while the final system of the season dissipated on May 3, 1998, after the season had officially ended on April 30. During the season 50 people died as a result of tropical cyclones, with the deadliest being Cyclone Martin with 27 known deaths. The strongest tropical cyclones during the season were Cyclone Ron and Cyclone Susan as both were estimated to have minimum pressures of , and were the most intense tropical cyclones on record in the South Pacific Ocean until Cyclone Zoe in 2002–03. After the season ended, 11 names had their names either removed or retired from the lists of names, after they caused significant impacts to South Pacific islands.
During the season, tropical cyclones were officially monitored by the Fiji Meteorological Service (FMS), New Zealand Met Service and the Australian Bureau of Meteorology. The United States Armed Forces through the Joint Typhoon Warning Center (JTWC) and Naval Pacific Meteorology and Oceanography Center (NPMOC), also monitored the basin and issued warnings for American interests. During the season the FMS issued warnings and assigned names to any tropical cyclones that developed between the Equator and 25°S while MetService issued warnings for any that were located to the south of 25°S. The JTWC issued warnings for American interests on any significant tropical cyclone that was located between 160°E and the 180° while the NPMOC issued warnings for tropical cyclones forming between 180° and the American coast. The FMS and MetService estimated sustained wind speeds over a 10-minute and used the Australian tropical cyclone intensity scale, while the JTWC and the NPMOC estimated sustained wind speeds over a 1-minute period which are compared to the Saffir-Simpson Hurricane Scale (SSHS). __TOC__
Seasonal outlooks Record TropicalCyclone Severe TropicalCyclone Ref Average activity: (1969–70 – 1996–97) 7 – 8 4 Record high activity: 1982–83: 14 1982–83:10 Record low activity 1994–95: 3 1994–95: 0 Activity during this season: 16 7
Ahead of the season officially starting on November 1, the Governor of American Samoa reported that traditionalists were forecasting a hurricane to affect American Samoa during the season after the big breadfruit and mango harvest that the island nation had experienced. The Cook Islands Meteorological Service and National Disasters Committee warned islanders that they could expect the "worst cyclone season in years" and urged residents to prepare. On November 27, New Zealand's National Institute of Water and Atmospheric Research (NIWA) issued a press release, which predicted that because of the strong El Niño phenomenon, there would be more tropical cyclones than average. In particular, they predicted that due to the strong El Niño, countries within the western part of the basin were likely to see fewer tropical cyclones during the season than countries within the eastern part of the basin. The Southern Cook Islands, Tonga, Tuvalu and French Polynesia were predicted to have an increased risk, while Fiji was forecast to have an average risk of being affected by a tropical cyclone. NIWA also reported that Cyclone Martin's impact on the Northern Cook Islands was an early sign of what could be expected during the season, because the system had occurred further east than normal. In mid-December, the Cook Islands Meteorological Service director commented to the media that from now on, by the time cyclones reached Rarotonga, they would have lost their intensity, while a spokesperson for NIWA commented that holidaymakers heading for the Pacific had little chance of running into a cyclone as the damaging core of the cyclone was expected to be over the ocean, while some cyclones were expected to be relatively weak. It was also noted that collectively the Pacific Islands Meteorological Services were collectively bracing for up to 15 tropical cyclones during the season, compared to 12 during an average season.
Seasonal summary
The 1997–98 season was one of the most active and longest South Pacific tropical cyclone seasons on record, with 16 tropical cyclones occurring within the South Pacific basin between 160°E and 120°W. The season was characterized by a very strong El Niño event, which caused the South Pacific Convergence Zone to move from its usual position near the Solomon Islands to the Northern Cook Islands. As a result, ten tropical cyclones formed to the east of the International Dateline, with seven of these tropical cyclones going on to affect French Polynesia.
After the 1996–97 season had one of the latest ends to a season on record, the 1997–98 season started early, with three tropical systems observed before the start of the season on November 1, 1997. Two other tropical systems, including the precursor tropical disturbance to Severe Tropical Cyclone Martin developed, before the official start of the season on November 1, 1997. Severe Tropical Cyclone Martin impacted the Cook Islands and French Polynesia, where it caused significant damage and 28 deaths during the opening days of the season. Tropical Cyclone Nute was named on November 18, before it moved out of the basin as a Category 2 tropical cyclone during November 19. During the rest of November, several tropical disturbances developed along the South Pacific Convergence Zone, including the precursor system to Severe Tropical Cyclone Osea and Tropical Cyclone Pam.
Severe Tropical Cyclones Ron and Susan were both the strongest tropical cyclones of the season and were thought to be the strongest tropical cyclones in the region since Severe Tropical Cyclone Hina of the 1984–85 season.
After the final warnings on Cyclone Tui were issued a weak circulation remained in the vicinity of Samoa for several days, before a westerly surge from the monsoon resulted in a tropical cyclone developing during February 1. However, due to uncertainties in the continuation of Tui after several other weak low-pressure areas had formed, the FMS decided to treat the cyclone as a separate system and named it Wes.
Tropical Cyclone Bart developed during the final days of the season and caused ten deaths and minor damage to French Polynesia, before it dissipated during May 3.
After the season had ended the names Alan, Katrina, Martin, Nute, Osea, Ron, Susan, Tui, Ursula, Veli, Yali and Zuman were either retired or removed from the list of names for the region, while the names Lusi, Pam and Bart were reused during the 2013–14, 2014–15 and 2016–17 seasons.
Systems
Tropical Cyclone Lusi
On October 4, a cyclonic circulation became evident within an area of convection, that was located about to the southeast of Yaren in Nauru. Over the next few days the system moved southwards, towards the upper subtropical ridge while outflow gradually developed further. During October 8, the system was classified as a tropical depression as the system rapidly developed further, before the JTWC initiated advisories on the depression and designated it as Tropical Cyclone 02P. The FMS subsequently named the depression Lusi during the next day, as the system had intensified into the earliest tropical cyclone since 1970, while located about to the northwest of Port Vila, Vanuatu. Over the next few days, Lusi moved towards the south-southeast, taking a so-called "gentleman's track" between Vanuatu and Fiji.
During October 10, the JTWC reported that Lusi had peaked with 1-minute sustained wind speeds of , while the system was located about to the northwest of Port Vila, Vanuatu. The FMS subsequently followed suit during the next day and estimated peak 10-minute sustained wind speeds of which made it a category 2 tropical cyclone. After it had peaked in intensity Lusi started to weaken in an area of cooler sea surface temperatures, while vertical wind shear increased because of a mid-level trough and strong north-westerlies. During October 12, Lusi degenerated into an extratropical cyclone, before the remnants were last noted to the northeast of New Zealand. There was no impact caused by Lusi on any island, however, widespread heavy rainfall and gale-force winds were reported on several Fijian Islands.
Tropical Depression 03P
On October 26, the FMS reported that a tropical depression had developed about to the west of the Fijian dependency of Rotuma. During that day, as the system moved south-westwards a central dense overcast became apparent in satellite imagery, before the JTWC initiated advisories and designated the system as Tropical Cyclone 03P. Within their first advisory, the JTWC noted that atmospheric convection associated with the system had fluctuated considerably over the last few days and that moderate to strong upper-level winds was creating significant vertical windshear over the system. As a result, they estimated that the system had peaked with 1-minute sustained winds of , despite estimates of being reached via the Dvorak Technique. Over the next day, the systems original low level circulation center slowly weakened and became indistinguishable from the surrounding atmospheric convection, before a new center developed to the northeast of the old centre. Deep convection had developed around this new centre, however, the convection did not persist as the system was located in a region of strong vertical windshear, before the depression dissipated to the northwest of Fiji during October 28.
Severe Tropical Cyclone Martin
On October 27, the FMS started to monitor a weak tropical disturbance that had developed to the north of the Northern Cook Islands. Over the next few days atmospheric convection surrounding the system remained disorganised, as the system moved to the southwest and was affected by strong upper-level north-easterly winds and moderate to strong vertical wind shear. Late on October 30, the NPMOC designated the disturbance as Tropical Cyclone 04P, after it had developed into a tropical depression. During the next day the system started to show a marked improvement in organisation and began rapidly developing, before the FMS named it Martin at 1500 UTC after it had developed into a category 1 tropical cyclone. When it was named, Martin was located about to the west of Manihiki Atoll in the Northern Cook Islands and had started to re-curve and move towards the south-east during that day. Early on November 1, the FMS reported that the system had become a category 2 tropical cyclone on the Australian scale, before the NPMOC reported that Martin had become equivalent to a category 1 hurricane on the SSHWS.