On 13 December, the BoM reported that Tropical Low 05U had formed approximately 170 km (110 mi) north of Cocos Islands, initially forecast to not develop further due to not conducive conditions.[36] However, over the next 5 days, conditions improved, with vertical wind shear decreasing.[37] At 11:30 UTC on 17 December, satellite imagery showed a partially exposed low-level center embedded in deep convection, prompting the JTWC's to issue a TCFA.[38] On the next day, the system strengthened into a Category 1-cyclone on the Australian scale, with BoM naming it Darian.[39] Later that day, the JTWC initiated advisories on the system and classified it as Tropical Cyclone 05S.[40] The BoM's assessed the cyclone to have strengthened into a Category 2 cyclone on 19 December and later to Category 3 cyclone on the Australian scale.[41][42] By 15:00 UTC, the JTWC upgraded Darian to a Category 1-equivalent cyclone on the Saffir-Simpson hurricane wind scale (SSHWS), with maximum 1-sustained winds of 140 km/h (85 mph).[43]
Darian then strengthened to a Category 3 equivalent cyclone on the SSHWS in an environment of low wind shear, warm sea surface temperatures and good upper-level poleward outflow, which led to the storm having a symmetric 23 nautical miles (43 km; 26 mi) eye.[44] The cyclone quickly intensified, and was upgraded to a Category 4 cyclone by the BoM.[45] Similarly, the JTWC's further upgraded Darian to a Category 4-equivalent cyclone around 21:00 UTC, while exhibiting some annular characteristics.[46] Darian continued to rapidly intensify, and reached Category 5 intensity on the Australian scale at 00:00 UTC on 21 December.[47][48] Later that day, it exited the basin and moved into the South-West Indian Ocean basin
Credits
Icons by Typhoon Force kim
Map by Jnlt
Music - INCL.CMD - Sunset city