Cyclone Susan

At this stage as the cyclone was moving towards the southwest it posed a severe threat to Vanuatu however, during that day Susan recurved towards the southeast and subsequently spared Vanuatu a direct hit. After sparing Vanuatu a direct hit, Susan started to accelerate towards the southeast and while starting to weaken significantly passed close enough to Fiji during January 7 and 8 to cause gale-force winds in Fiji's southern and western islands. While continuing to move towards the southeast, Susan started to interact with Severe Tropical Cyclone Ron during January 8 before it absorbed Ron by 0600 UTC the next day and starting to transition into an extratropical cyclone.

The extratropical remnants of the combined systems were then monitored for another day until they were last noted on January 10, bringing an unseasonable cold snap to New Zealand. Despite sparing Vanuatu and Fiji direct hits, heavy rain and gale-force winds associated with Susan were reported to have caused minor damage to several Vanuatuan and Fijian islands. These islands included Viti Levu where a possible tornado destroyed the roof of a shopping centre and the Vanuatuan island of Ambrym, where a woman died after being hit by a falling coconut tree, while gathering supplies to secure her house with.

Meteorological history

On December 20, 1997, the Fiji Meteorological Service (FMS) started to monitor a weak tropical disturbance that was located about 915 km (570 mi) to the northwest of Pago Pago in American Samoa. Over the next couple of weeks, the system gradually moved towards the west-southwest, without developing into a tropical cyclone. During the opening days of January 1998, a subtropical mid-level ridge of high pressure developed to the south of the system between Fiji and Vanuatu, which provided an area of low vertical wind shear in which the disturbance could intensify. As a result, the system started to show signs of significant development while located near the Fiji dependency of Rotuma, before on January 3, the United States Joint Typhoon Warning Center (JTWC) initiated warnings on the system and designated it as Tropical Cyclone 11P. This was followed by the FMS, which reported that the system had become a Category 1 tropical cyclone, on the Australian tropical cyclone intensity scale and named it Susan.

After it had been named, Susan continued to move towards the west-southwest and started to pose a severe threat to northern Vanuatu, as it continued to rapidly intensify. It was classified as a category 3 severe tropical cyclone during January 4, as an eye appeared on satellite imagery, atmospheric convection increased and clouds tops significantly cooled. The ridge of high pressure also started to weaken as it interacted with a trough of low pressure, which meant that the cyclone started to turn towards the south-southwest.

During January 5, the FMS reported that along with Severe Tropical Cyclone Ron, Susan had become a category 5 severe tropical cyclone and that both systems had peaked with 10-minute sustained wind speeds of 230 km/h (145 mph) and a minimum pressure of 900 hPa (26.58 inHg). As a result, both systems were considered to be two of the most intense tropical cyclones, within the South Pacific basin, since Severe Tropical Cyclone Hina of 1984-85. At around the same time, the JTWC who reported that the system had peaked with 1-minute sustained wind speeds of 260 km/h (160 mph), which made it a category 5 on the Saffir-Simpson hurricane wind scale. As it peaked in intensity, Susan was located about 415 km (260 mi) to the northeast of Port Vila in Vanuatu and had started to recurve by 70 degrees towards a large weakness in the subtropical ridge.

Over the next couple of days, Susan maintained its peak intensity and accelerated south-eastwards, as it came under the influence of a north-westerly steering flow, which was associated with a trough of low pressure. As a result, the system started to pose a threat to the island nation of Fiji and weaken as it interacted with cooler sea surface temperatures, cooler air and increased vertical windshear. During January 7, Susan's eye became ragged as it continued to weaken, with the FMS reporting that the system had weakened into a category 4 severe tropical cyclone. During that day, the system passed close enough to Fiji, to produce gale-force winds over several of the southern and western Fijian Islands. Susan subsequently absorbed the remnants of Severe Tropical Cyclone Ron during January 8, before it rapidly weakened and quickly transitioned into an extratropical cyclone, while it was located about 1,300 km (810 mi) to the northeast of Auckland, New Zealand. The combined system was monitored for another day, before it was last noted during January 10, bringing an unseasonable cold snap to New Zealand.