The Trans-Australian Railway line and the Eyre Highway, key freight routes running between WA and South Australia through the Nullarbor, have been closed since the weekend with water over roads and railways.
More than 155mm of rain has fallen on Rawlinna, 900km east of Perth, since 9am on Friday, while the Bureau of Meteorology has forecast 24-hour totals of up to 130mm for parts of the Goldfields, Eucla and South Interior districts.
National weather update for this week: Temps to drop on the south-east coast from Tuesday but will stay high inland. More rain for interior & southern — Bureau of Meteorology, Australia (@BOM_au) #WA, Severe Weather Warning in place. Potential tropical #cyclone developing north-west of WA. Latest: https://t.co/jlOoTZL1iF pic.twitter.com/2hoVABMIR8March 11, 2024
Average rainfall in those areas is around 260mm per year.
"A near-stationary trough over southeastern Western Australia will remain in the area until the middle of the week," the BOM said on Tuesday.
"A moist airmass drawn southward from the tropics is combining with this trough to produce a band of heavy rainfall, with embedded thunderstorms capable of locally intense falls."
The system is expected to persist throughout the rest of Tuesday and possibly into Wednesday, with dangerous and life-threatening flash flooding possible.
WA's Department of Fire and Emergency Services warned residents in Rawlinna as well as Carnegie, Cocklebiddy and Eyre to seek shelter, stand clear of windows and refrain from driving through floodwaters.
"If you live in parts of the Goldfields, Eucla and South Interior districts you should take action and stay safe with severe weather to come," the department advised.
"This is not typical weather for southeastern Western Australia."
The Nullarbor typically has a desert climate, with arid to semi-arid conditions. (Murray Cox/AAP PHOTOS)
Given the anticipated prolonged rainfall, the east-west rail line is expected to remain closed until later in the week, the Australian Rail Track Corporation said.
The iconic Indian-Pacific train service that operates between Perth and Sydney via Adelaide has been cancelled as a result.
"Due to a severe weather incident on the Nullarbor, the Indian Pacific schedule until Saturday 16 March has been impacted," its website says.
"At this time, all departures from Sunday 17 March will operate as scheduled."
Meanwhile, a tropical low in the Indian Ocean is expected to develop into a tropical cyclone as it tracks closerto the Pilbara coast later this week.
There is a possibility it will bring gale force winds to Christmas Island as it passes to the south on Tuesday.
