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Cyclone Sarai

Category 2 South Pacific cyclone of 2019

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Ahead of Sarai, gale warnings, tropical cyclone alerts and heavy rain warnings were imposed for Fiji. These warnings were also raised on Tonga, Niue, and the southern Cook Islands. National and international flights were also canceled and many people are evacuated to different emergency shelters. Impacts were felt, starting on December 22 on the northern division of Fiji. The impacts of the cyclone were wide, from the country to Tonga and the Cook Islands. In total, Sarai claimed two lives, all in Fiji alone, and leftover FJ$5 million (US$2.3 million) worth of damages on that country. The damages in other countries affected by the cyclone, if any, were minor.

Meteorological history

During December 20, the Fiji Meteorological Service (FMS) started to monitor an area of low pressure, located near the Solomon Islands for the possibility of tropical cyclogenesis. Over the next few days, they continued to monitor the system and assessed its potential to become a tropical cyclone. During December 23, the FMS reported that the area of low pressure had developed into a tropical disturbance and assigned it the designator 03F, while it was located about 630 km (390 mi) to the west of Tuvalu. At this time the system was poorly organised with deep atmospheric convection, displaced to the north and east of its broad and elongated low-level circulation. The disturbance was also located underneath an upper ridge of high pressure within a favourable environment for further development, with low to moderate vertical windshear and warm sea surface temperatures of 29–30 °C (84–86 °F). The FMS expected at this time that the disturbance would track just to the west of the Yasawa and Mamanuca Islands, before turning and moving southeastwards to the south of Kadavu towards the southern Lau Islands. However, it was noted that the movement of tropical cyclones could be erratic within the region and that some weather models were predicting that the system would make landfall on Viti Levu.

Over the next couple of days, the system moved southwards and gradually developed further with its overall organisation improving, before it was classified as a tropical depression by the FMS during December 25. After being classified as a tropical depression, the system continued to develop, with its outflow improving and deep convection wrapping on to the systems low level circulation center. During December 26, the United States Joint Typhoon Warning Center initiated advisories on the depression and designated it as Tropical Cyclone 04P, before the FMS reported that the system had become a Category 1 tropical cyclone on the Australian tropical cyclone intensity scale and named it Sarai. At this time, Sarai was being steered southwards to the west of Fiji, along the edge of a near-equatorial ridge of high pressure and the jetstream. Over the next couple of days, the system gradually intensified further and was classified as a Category 2 tropical cyclone during December 27, while it was located around 220 km (135 mi) to the west of Nadi, Fiji. As the system turned south-eastwards later that day, the JTWC noted that there was significant uncertainty in the model guidance over Sarai's future track, as a trough of low pressure approached the ridge of high pressure and weakened it. In particular, the ECMWF and NAVGEM models showed that the system would meander near Viti Levu or move northwards over Fiji, while other models showed that the system would move eastwards towards Fiji's Lau Islands and Tonga or northeastwards towards American Samoa.

During December 28, as Sarai passed about 100 km (60 mi) to the south of Fiji's Kadavu Island, the FMS estimated that the system had peaked as a Category 2 tropical cyclone with 10-minute sustained winds of 110 km/h (70 mph). During that day as the system continued to move eastwards the system briefly developed an eye, while the model guidance came into better agreement over Sarai's future track. The JTWC also estimated that Sarai had peaked with 1-minute sustained winds of 140 km/h (85 mph), which made it equivalent to a Category 1 hurricane on the Saffir-Simpson hurricane wind scale. Over the next couple of days, the system gradually weakened as it was steered eastwards towards Tonga, with its low level circulation center becoming partially exposed and atmospheric convection significantly decreased as vertical wind shear increased. During December 30, the FMS reported that Sarai had weakened into a Category 1 tropical cyclone, before it passed over the Tongan island groups of Ha'apai and Tongatapu later that day. The system subsequently rapidly decayed during the next day, with atmospheric convection was displaced over 90 km (55 mi) to the southeast of the systems ragged and fully exposed low level circulation center. As a result, the JTWC issued their final advisory on Sarai, while the FMS reported that had degenerated into a tropical depression. The remnant tropical depression continued to move east-southeastwards and passed about 215 km (135 mi) to the southeast of the island nation of Niue later that day. The system was last noted by the FMS during January 2, while it was located about 180 km (110 mi) to the southeast of Rarotonga in the Cook Islands.

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