A unique cyclone event off the coast of Western Australia will bring gale-force winds and heavy rain that could lead to flash flooding at the weekend.
A blue alert was yesterday issued for residents living between Coral Bay and Lancelin after two tropical cyclones, Seroja and Odette, formed off the West Australian coast.
Odette was downgraded to an ex-tropical cyclone by the Bureau of Meteorology on Saturday.
Both will make their way down the coast over Saturday and Sunday but only Seroja is expected to make landfall.
A BOM spokesman said residents should prepare for intense winds, rain and possible flash flooding over the weekend and Monday.
Meteorologist Todd Smith said the interaction between the two systems earlier this week was very unusual as it had not been seen off the WA coast for decades.
He said another unusual trait included TC Seroja crossing the coast with strong conditions as most of the time, cyclones would weaken in intensity as they moved closer to land.
â€œThe last time a cyclone affected the Geraldton area was 1990, and even that was a weak tropical cyclone below intensity,â€ Mr Smith said.
Ex-Tropical Cyclone Odette weakening but could result in a brief period of strong winds between Exmouth and Coral Bay this afternoon and evening. Refer to Severe Weather Warning for details. #CycloneOdettehttps://t.co/B1MVXBYXhhpic.twitter.com/p8Ol9sHFFJ
â€” Bureau of Meteorology, Western Australia (@BOM_WA) April 10, 2021
Meteorologist Jonathan How said Odette would weaken through Saturday as it swings along the eastern flank of TC Seroja.
â€œ(It will) bring a period of strong winds towards the Exmouth area towards the evening,â€ Mr How said.
â€œSeroja, however, will intensify and conditions will deteriorate during Sunday.â€
Tropical Cyclone Seroja expected to bring dangerous weather conditions to the west coast during Sunday or Monday.The track map shows #CycloneSeroja intensifying to category 3 on Saturday and reaching the coast as a category 2 system late Sunday or Monday. https://t.co/B1MVXBYXhhpic.twitter.com/v2D5slFCij
â€” Bureau of Meteorology, Western Australia (@BOM_WA) April 9, 2021
Odette, originally a tropical low, formed into a tropical cyclone after circling each other over the Indian Ocean on Thursday.
Mr How said it was known as the Fujiwhara effect â€“ where both systems â€œdumbbellâ€ around each other â€“ something â€œnot often seenâ€.
TC Seroja is forecast to cross the coast later tonight, with the centre crossing between the Carnarvon and Jurien Bay regions.
The system is likely to bring wind gusts of up to 125kmh, heavy rains and dangerous tides.
â€œRain and strong easterly winds from the system could reach as far south as Perth,â€ Mr How said.