Cyclone Betsy

Severe Tropical Cyclone Betsy
Category 4 severe tropical cyclone (Aus scale)
Category 2 (Saffir–Simpson scale)

Cyclone Betsy on January 10, while near its peak intensity.
Formed January 4, 1992 (1992-01-04)
Dissipated January 19, 1992 (1992-01-19)
(Extratropical after January 15, 1992)
Highest winds 10-minute sustained: 165 km/h (105 mph)
1-minute sustained: 175 km/h (110 mph)
Lowest pressure 940 hPa (mbar); 27.76 inHg
Fatalities 6
Areas affected Kiribati, Tuvalu, Solomon Islands, Vanuatu, New Caledonia
Part of the 1991–92 South Pacific cyclone season

Severe Tropical Cyclone Betsy impacted 8 island nations.

Meteorological history

Map plotting the track and intensity of the storm according to the Saffir–Simpson hurricane wind scale

In early January 1992, an equatorial westerly wind burst caused a surge of stronger than normal low level westerly winds, to develop on the northern side of the Southern Hemisphere monsoon trough to the east of New Guinea.[1][2] Enhanced convection associated with the wind burst gradually became more organized and by late on January 5, a tropical depression had developed within the monsoon trough to the west of Tuvalu.[1] Early on January 6, the JTWC initiated advisories on the depression and designated it as Tropical Cyclone 11P, as it moved westwards.[3][4] During that day the system gradually developed further with the cloud system becoming more symmetrical, while strong upper-level outflow and weak vertical wind shear favored further development.[1][4] Later that day TCWC Nadi named the system Betsy at 19:15 UTC, after the system had developed into a category 1 tropical cyclone on the Australian tropical cyclone intensity scale.[1][4]

After being named the system moved erratically towards the south-southeast, as it interacted with a mid troposphere trough of low pressure.[4][5] Throughout January 7, Betsy continued to intensify under the influence of a strong upper level anticyclone, located to its north and developed an eye feature.[4][5][6] The system also passed about 95 km (60 mi) to the east of the Solomon Island: Anuta, where winds of 85–100 km/h (55–60 mph) were recorded.[4][7] Betsy subsequently changed its course and started to move towards the south-southwest, as it interacted with the upper level easterlies and a ridge of high pressure built to the south-east of the system.[4][5] During February 8, the system became a category 3 severe tropical cyclone before it crossed central parts of Vanuatu early the next day, with the eye passing over, or very close to the islands of Ambrym and Malakula between 0000 and 0500 UTC.[4]

Preparations and impact

Betsy directly affected the Pacific island nations of Vanuatu, New Caledonia, New Zealand and the Solomon Islands, while it also indirectly affected the island nations of Papua New Guinea, Fiji, Tuvalu and Kiribati.

Tropical cyclone Betsy directly affected three countries, and indirectly affected two others. Some meteorological data reported from Vanuatu, the worst affected during the passage of Betsy.

Solomon Islands

Betsy impacted the Solomon Islands Temotu Province between January 6–8, which had been impacted by Severe Tropical Cyclone Tia seven weeks earlier.[4][8] During January 7, the system passed about 95 km (60 mi) to the east of Anuta, where wind speeds of 85–100 km/h (55–60 mph) were recorded by the automatic weather station on the island.[4][7] Later that day the system subsequently passed, about 160 km (100 mi) to the east of Tikopia during January 7.[4]

Vanuatu

Cyclone Betsy was the second of six tropical cyclones to affect Vanuatu during the 1991-92 season, seven weeks after Severe Tropical Cyclone Tia brought gale force winds to northern Vanuatu. The system affected Vanuatu between January 7–9, with gale, storm and hurricane-force winds reported at various locations around the island nation including on Malakula Island.

, started reporting average winds of gale force from 4 a.m. on the 9th (Vanuatu time) increasing to near storm force for a while around midday. Winds then started to decrease gradually.

However, the strongest winds reported were at Lamap (Malakula Island), where hurricane-force winds were recorded between 3 and 5 p.m. that day. Gale force winds were also reported for a time from Aneityum. It is estimated from the meteorological information available, sustained winds during between 75 and 80 knots.

northern and central regions of Vanuatu were the worst affectedt including the islands of Espiritu Santo, Maevo, Pentecost, Ambrym, Paama, Epi and Malakula. Fortunately, no loss of life was reported but it is understood that there was a considerable number of injuries.

On Pentecost and Santo many houses were damaged or destroyed and on Santo roads were blocked by landslides. On Efate, at Port Vila many houses suffered roof damage, some power lines were brought down, and there was a fairly major crop damage north of Vila. However, by far the worst damage on Efate was due to the storm surge, estimated at about three metres, on the northeast part of the island. It washed away the road totally for some kilometres, parts of some villages and the resort of Takara completely. As the road was built during World War Two it is probable that no comparable surge has affected the area for 50 years or more.

Aftermath

On January 10, Vanuatu's Minister for Foreign Affairs, formally submitted a request to donor countries for foreign aid.[9] As a result of this request two aircraft a French Guardian and an Australian Orion, arrived in Vanuatu during the next day for surveillance operations. The planes completed their operations early on January 12 and returned to their countries, before a donor aid meeting involving the Australian, French, New Zealand and British high commissions was held later that day.

New Caledonia

Cyclone Betsy affected New Caledonia between January 9–10, and passed about 195 km (120 mi) to the north of the Belop islands. Gale force winds associated with Betsy, were experienced as far south as Nouméa.

Other islands

Late on January 3, westerly winds of between 75–85 km/h (45–55 mph), were reported on the northern side of the monsoon trough in Nauru.[4] At around the same time parts of Kiribati, were affected by squally westerly winds.[4] Five people died in accidents related to the strong winds, including one when the roof of a mission building collapsed.[4] During January 7, heavy swell generated by the system caused flooding and minor damage on the Northern Tuvaluan islands.[4]

References

  1. 1 2 3 4 Gill, Jonathan P. "The South Pacific and Southeast Indian Ocean Tropical Cyclone Season 1991–1992" (PDF). Australian Meteorological Magazine. Australian Bureau of Meteorology. 43: 181 – 192. Archived (PDF) from the original on July 17, 2012. Retrieved July 11, 2012.
  2. ↑ Stremler, David J; Joint Typhoon Warning Center; Naval Western Oceanography Center (1993). Typhoon Axel (01W) (PDF) (1992 Annual Tropical Cyclone Report). United States Navy, United States Airforce. pp. 36–41. Archived (PDF) from the original on March 18, 2012. Retrieved September 8, 2013.
  3. ↑ Joint Typhoon Warning Center; Naval Western Oceanography Center (1993). 6. Tropical Cyclone Warning Verification Statistics: Southern Hemisphere (PDF) (1992 Annual Tropical Cyclone Report). United States Navy, United States Airforce. pp. 240–247. Archived (PDF) from the original on March 18, 2012. Retrieved March 25, 2013.
  4. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Tropical Cyclone Betsy, January 4 – 15, 1992 (Tropical Cyclone Report). Fiji Meteorological Service. Archived from the original on March 19, 2013. Retrieved September 8, 2013.
  5. 1 2 3 http://www.bom.gov.au/climate/ntregion/statements/tropical/dtds-199201.pdf
  6. ↑ MetService (May 22, 2009). "TCWC Wellington Best Track Data 1967–2006". International Best Track Archive for Climate Stewardship.
  7. 1 2 "Tropical Cyclones/Depressions that passed through Solomon Islands Region" (PDF). Solomon Islands Meteorological Service. September 13, 2009. Archived from the original (PDF) on March 9, 2013. Retrieved September 21, 2011.
  8. ↑ Ward, Graham F.A (February 12, 1992). Tropical Cyclone Tia, November 14 - 21, 1991 (PDF) (Tropical Cyclone Report 92/3). Fiji Meteorological Service. Archived (PDF) from the original on September 23, 2013. Retrieved December 20, 2015.
  9. ↑ http://www.pacificdisaster.net/pdnadmin/data/original/JB_DM184_PNG_1992_emergemcy_response.pdf
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