Narelle has reformed into a category two system in Western Australia's northwest and is sitting about 330km northeast of Port Hedland.
The storm, which is currently generating wind gusts up to 120km/hr, is expected to intensify into a category-four cyclone in the coming days after tracking southwest along the Pilbara coast.
"That is a really powerful, really major weather system," Senior Meteorologist Angus Hines said on Wednesday.
Narelle is likely to cross the coast on Saturday morning as a severe, category-three storm - which can generate gusts of up to 224km/hr - between the towns of Carnarvon and Kalbarri in the Shark Bay area.
It will then track inland and head south over the wheatbelt region on a path that will take it east of Perth towards WA's southern coastline near Esperance.
"This could occur as a category one tropical cyclone, but maybe it will have already fallen back into a tropical low-pressure area by the time it gets near Perth," Mr Hines said.
Widespread weather impacts are expected on the west coast on Friday and over the weekend, including strong winds and heavy rain up to 100mm between Geraldton and Bunbury.
"That is absolutely enough rainfall to lead to flash flooding, or rivers rising and bursting their banks," Mr Hines said.
Destructive winds, with gusts up to 140 km/hr, large waves and abnormally high tides are possible over the next few days between Karratha and Coral Bay as Narelle strengthens out to sea.
The cyclone first made landfall on March 20 in far north Queensland before tracking west across the Gulf of Carpentaria.
It became a tropical low after making landfall in the Northern Territory on the weekend, forcing hundreds to evacuate from floodwaters.
Its impact is still being felt in Katherine, south of Darwin, where the river height is expected to approach the major flood level of 17.5 metres on Wednesday, threatening to inundate homes in low-lying areas.
Shelters were ready to take people impacted by flooding, and a portable field hospital was operating while the threat remained, NT Deputy Chief Minister Gerard Maley told reporters on Wednesday.
Earlier this month, the flood level hit 19.2 metres, impacting homes and businesses.
