Cyclone Osea

Cyclone Osea

Category 3 cyclone (Australian scale) Category 2 tropical cyclone (SSHWS)
Cyclone Osea near peak intensity on November 27
Formed	November 24, 1997
Dissipated	November 28, 1997
Highest winds	10-minute sustained: 150 km/h (90 mph) 1-minute sustained: 165 km/h (105 mph)
Lowest pressure	950 mbar (hPa); 28.05 inHg
Fatalities	None reported
Areas affected	French Polynesia
Part of the 1997–98 South Pacific cyclone season

Cyclone Osea was the second of seven cyclones to affect French Polynesia during the 1997–98 South Pacific cyclone season. Forming on November 22, the storm initially remained weak. Moving south and later east, it was named Osea on November 24 after achieving windspeeds equal to a Category 1 cyclone on the Australian tropical cyclone intensity scale. Continuing to intensify, Osea soon reached its peak intensity of 90 mph (145 km/h). Afterwords, Osea began to weaken because of increased wind shear, and the cyclone started moving southeast. By November 28, Osea was no longer a tropical cyclone.

The cyclone brought major damage to some islands in French Polynesia. Around 95% of the infrastructure in Maupiti was destroyed, including 77 homes, an airport, and a town hall. About 30% of the infrastructure in Bora-Bora was destroyed, as well as 309 homes and many yachts. Many roads were also damaged. Almost everything on the north side of the island was destroyed. However, no deaths were reported. The name Osea was retired after this usage of the name.

Meteorological history

On November 22, 1997, the Fiji Meteorological Service's Regional Specialized Meteorological Center in Nadi, Fiji (RSMC Nadi) and the Naval Pacific Meteorology and Oceanography Center (NPMOC) started to monitor a tropical depression that had developed about 465 km (290 mi) to the northeast of the Northern Cook Island: Manihiki.^[1][2] Over the next two days the depression gradually developed further, as it slowly moved southwards due to a weakness in the subtropical ridge of high pressure.^[1][3] At 1200 UTC on November 23, the NPMOC reported that the depression had become equivalent to a tropical storm and assigned it the designation 06P. Twelve hours later RSMC Nadi named the system Osea after it had developed into a Category 1 tropical cyclone on the Australian tropical cyclone intensity scale.^[4][3] Thereafter, Osea started moving towards the southeast, as an area of high pressure started to develop to the south of the system.^[1][5]

During November 25, RSMC Nadi estimated that Osea had become a Category 3 severe tropical cyclone, while the NPMOC announced that the system had become equivalent to a Category 1 hurricane on the Saffir-Simpson hurricane wind scale as it moved through French Polynesia. The next day both agency's reported that Severe Tropical Cyclone Osea had reached its peak intensity.^[1][6][7] RSMC Nadi reported 10-minute sustained winds of 150 km/h (90 mph); the NPMOC reported peak 1-minute sustained windspeeds of 165 km/h (105 mph) which made it equivalent to a Category 2 hurricane on the SSHS.^[8][2] After attaining peak intensity, Osea gradually weakened. By November 27, the NPMOC had issued their final warning on the system because the convection had become dislocated over 185 km (115 mi) from the low level circulation center due to increased wind shear.^[9] RSMC Nadi subsequently monitored Osea for another 24 hours before it was last noted by the agency on November 28, around the time it degenerated into a tropical depression.^[4][8]

Preparations, impact, and aftermath

Prior the arrival of Cyclone Osea on November 24, various cyclone alerts and warnings were issued for the whole of French Polynesia, while authorities strengthened security measures and advised people not to drive.^[10][11] Throughout the archipelago schools were closed. Furthermore, people on the atoll of Scilly were evacuated by helicopter to other islands.^[10]

Cyclone Osea was extremely destructive to some of the islands in French Polynesia. Over 700 homes were destroyed or severely damaged on Maupiti, Bora-Bora, and Raiatea. Several roofs were blown off of buildings across the archipelago.^[12] On Maupiti, an island with a population of 1,100, about 95% of the infrastructure was destroyed. The town hall, two schools, and an airfield were destroyed.^[13] The town hall was originally being used as an emergency shelter, but was later evacuated due to strong winds^[14] and was later destroyed. Furthermore, many roadways and highways were blocked due to flooding.^[15] In addition, 77 homes on the island were destroyed. All but three homes that belonged to Mormons on the island were destroyed.^[16]

On Bora-Bora, an island which had a population of 4,500 at the time, roughly 30% of the infrastructure was destroyed,^[13] including 309 houses. Hotels were also impacted during the storm.^[17] On the north side of Bora Bora, nearly everything was destroyed, including the village of Vaitape and a local yacht club.^[18] Across Vaitape, roads were blocked by fallen trees and telecommunication lines were severed due to high winds. Seven people on the island were reportedly slightly injured.^[7][19] In addition, the islands of Tahaa, Raiatea, and Moorea all sustained damage, though yachts in Raiatea managed to survive unscathed.^[18] In another archipelago, 700 homes and various public infrastructures were at least somewhat destroyed by Osea.^[20] In addition to the impact on infrastructure, banana trees were knocked down due to the winds, especially in mountain gardens.^[21] Throughout the impacted region, no deaths were reported.^[13]

Osea was the second tropical cyclone to impact French Polynesia during the season; Cyclone Martin had impacted the islands a few weeks earlier. In the aftermath of the storm, disaster aid was delivered to the victims of Osea.^[17] President Gaston Flosse, accompanied by technicians, arrived in Maupiti to help repair the island's electrical and hydraulic systems.^[22] A Latter-Day Saint meeting house was used as an emergency shelter, though the house itself sustained minor damage from the storm.^[15] The name Osea was later retired from the South Pacific list of tropical cyclone names.^[23]

See also

• List of retired South Pacific tropical cyclone names

References

External links

• World Meteorological Organization
• Fiji Meteorological Service
• Meteorological Service of New Zealand
• Joint Typhoon Warning Center

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