Tropical Cyclone Betsy

6 - 13 January 1992

Summary

Tropical cyclone Betsy was the second cyclone to affect Vanuatu during 1991-92 and was considerably more damaging than its predecessor, tropical cyclone Tia . Unusually for the time of year, Betsy formed as a southern hemisphere twin to typhoon Axel in the northern hemisphere. ( Axel tracked westward and was subsequently associated with the spin up of tropical cyclone Mark in the Gulf of Carpentaria.)

Between 3 and 5 January, strong to gale-force westerly winds developed on the northern side of the southern hemisphere monsoon trough. Enhanced convection associated with the westerly burst gradually became more organised within the trough west of Tuvalu, and by 1800 5 January, a deep tropical depression was evident. The depression continued intensifying as it drifted slowly west and at 1900 UTC 6 January was named tropical cyclone Betsy . During the next 12 hours, Betsy steadily deepened and tracked south-southeast at around 5 m/s. Mean winds associated with the cyclone reached storm force at 2100 UTC 7 January and the system turned to the southwest in response to increasing deep-layer mean easterlies. This brought the cyclone on a direct course for the central Vanuatu Islands.

By 1800 UTC 8 January, mean winds associated with tropical cyclone Betsy had reached hurricane force. Six hours later, the destructive core of the cyclone struck the islands of Ambrym and Malakula in central Vanuatu. On Malakula, sustained winds of 33 m/s were recorded between 0400 and 0500 UTC 9 January and the MSLP dropped to 959 hPa. At this point, Betsy possessed a large ragged eye with a diameter of over 110 km. Betsy continued to intensify after leaving Vanuatu, and reached maximum intensity (mean winds estimated to 45 m/s) at around 0000 UTC 10 January whilst 200 km to the north of New Caledonia.

By 0600 UTC 11 January, satellite imagery indicated that Betsy was losing organisation, with the large eye (diameter of 165 km) rapidly shrinking and becoming elongated and ragged. Around 1200 UTC 11 January, Betsy recurved sharply to the south under the influence of an approaching upper trough. Environmental shearing increased over the next few days, and by 13 January Betsy had dissipated as a tropical cyclone. The extratropical remnants continued drifting southeast and then east, passing close to the northern coast of New Zealand on 17 January.

Tropical cyclone Betsy wrought considerable damage in Vanuatu and was responsible for the deaths of two people. The worst affected island was Efate, where an estimated three-metre storm surge washed away kilometres of coastal road, parts of villages and the entire resort of Takara. Elsewhere on Efate, houses lost roofing, major crop damage was reported north of Vila, and power lines were brought down. On Pentecost Island and Espiritu Santo, many houses were destroyed or damaged and roads were blocked by mud slides.

Track and intensity

Best Track of Tropical Cyclone Betsy