While Joyce has made landfall and will continue to weaken, the threat for flooding and travel delays will persist across southestern Australia into Monday.
Joyce made landfall just west of Wallal Downs on Friday, local time, as a Category 1 cyclone (the equivalent of a tropical storm in the northern Pacific and Atlantic oceans). Joyce weakened to a tropical rainstorm on Friday night as it pushed inland.
Into Monday, downpours will spread farther south across Western Australia’s Wheatbelt, Perth and Peel regions through Monday.
While the flood threat will gradually lessen as Joyce moves further away from the tropical moisture along the Pilbara and Kimberley coasts, heavy downpours are still likely.
Heavy rain amounts have soaked the coastline where Joyce made landfall. Already, 150-210 mm (6-8 inches) has fallen between Wallal Downs and Bidyadanga.
While similar amounts are not expected in southwest Australia, 25-75 mm (1-3 inches) of rain will still soak the region. Isolated totals to 100 mm (4 inches) are possible to the north of Perth.
Residents living in flood-prone areas are being put on alert as the heavy rain threat may cause low-lying and poor drainage areas to quickly become inundated with flood waters. Creeks and smaller rivers may overflow their banks.
“Any flooding would make transportation to the coast for shipping problematic with washed-out roads and/or rails,” AccuWeather Senior Meteorologist Jason Nicholls said.
Even if flooding does not ensue, outdoor plans can be ruined and delays may plague travelers.
Motorists would face reduced visibility and a heightened risk of vehicles hydroplaning when traveling at highway speeds.
The downpours may focus on areas south of Perth on Monday night. Lingering showers and thunderstorms are possible on Tuesday.
“Joyce is the second landfalling-cyclone to strike Australia so far this season, which is equal to all of the 2016-2017 season, and the current season runs through the end of April,” Nicholls said.
Nicholls is anticipating a near-normal tropical season across the Australian Basin.
He adds “Another tropical cyclone may threaten to form along the northwest Australia coast early next week.”
A total of 10 tropical cyclones are expected. Four to five of those can become severe tropical cyclones, with sustained winds in excess of 118 km/h (73 mph).