Cyclone Seroja

Severe Tropical Cyclone Seroja was the third-deadliest tropical cyclone on record in the Australian region, behind Cyclone Mahina in 1899 and the Flores cyclone in 1973. Seroja brought historic flooding and landslides to portions of southern Indonesia and Timor-Leste and later went on to make landfall in Western Australia's Mid West region, becoming the first to do so since Cyclone Elaine in 1999. The twenty-second tropical low, seventh tropical cyclone, and third severe tropical cyclone of the 2020–21 Australian region cyclone season, the precursor of Seroja formed off the south coast of Timor island as Tropical Low 22U at 18:00 UTC on 3 April 2021; its genesis was related to convectively coupled equatorial waves. The tropical low moved very slowly near the island, while the system's thunderstorms increased in organization. The low intensified into Tropical Cyclone Seroja by 4 April, while it was passing north of Rote Island, while continuing its slow strengthening trend. Due to the presence of Tropical Cyclone Odette in Seroja's vicinity, interaction was anticipated as the storm moved away from Indonesia and Timor-Leste. Its intensity fluctuated as it moved southwest, with its strengthening being highly hindered due to interaction with Odette. This caused the system to weaken as Seroja moved closer to it, due to a phenomenon known as the Fujiwhara effect. Eventually, Seroja began to restrengthen and weaken Odette, with Seroja absorbing Odette into its circulation on 10 April. Due to Odette, Seroja was steered to the southeast towards Australia, before strengthening even further. At around 8 p.m. local time on 11 April, Seroja made landfall on the western coastline of Western Australia as a Category 3 severe tropical cyclone, slightly south of the coastal town of Kalbarri, bringing heavy rain and hurricane-force wind gusts (about 170 km/h, or 110 mph). Later that day, Seroja...