Cyclone Veronica is gaining strength as it approaches Western Australia's Pilbara coast with a predicted 11-metre storm surge, but it remains unclear exactly where it will make landfall.
Communities along the state's north-west coast are preparing themselves for the arrival of the category four tropical cyclone, which is now about 355 kilometres north-northwest of Port Hedland, home to one of the world's busiest ports.
While it is still strengthening, forecasters say it may not develop into a category five system as initially thought.
The cyclone is due to strike the coast sometime on Sunday somewhere between Port Hedland and Karratha, a distance of almost 200 kilometres, and the Bureau of Meteorology (BOM) has warned "a severe impact" is likely.
Very destructive winds will develop on Saturday and could reach gale force by tonight, with Cyclone Veronica sparking warnings of widespread heavy rainfall, a damaging storm surge and major flooding.
In Port Hedland, people in low-lying areas between the port and Pretty Pool, including the suburb of Wedgefield, are being urged to evacuate.
A huge tidal surge is forecast to result in waves up to 4 metres higher than the usual 7.5-metre tides experienced at this time of year.
BOM warns of major flooding
The BOM said the cyclone was expected to track south to south-east towards the Pilbara coast over the weekend.
"People between Mardie and Pardoo should be prepared for cyclonic weather and listen to emergency messages coming out from DFES," BOM senior forecaster Matt Boterhoven said,
"We'll see gales develop maybe as early as Friday evening but more likely during Saturday, and they'll extend east to possibly east to Wallal Downs and further west to Onslow.
"As the system approaches the coast over the weekend we'll see destructive gusts develop around Dampier to Pardoo, possibly late Saturday, and very destructive winds in excess of 165 kilometres an hour are possible near the cyclone centre as it approaches the coast.
"We're also expecting widespread heavy rainfall which is conducive to some major flooding over the Pilbara over the weekend and into early next week.
"Also it's likely to be slow moving when it approaches the coast, [so] we're expecting a dangerous storm tide to emerge."
More than 500mm of rain forecast
The cyclone is forecast to become slow moving after crossing the coast.
But the BOM warned "this could mean that the impacts of wind and heavy rain may be sustained for a considerable period".
More than 500 millimetres of rain could fall between Saturday and Tuesday in the areas closest to the cyclone's track, the BOM said.
"Tides are likely to rise significantly above the normal high tide mark with damaging waves and very dangerous coastal inundation," it said in an advice.
Shelves emptied, mine workers sent home
Preparations are well underway in communities along the coast as the cyclone approaches land.
In Port Hedland, supermarket shelves have been emptied of essentials like bottled water, windows are being boarded up and loose items secured.
Mine workers have been sent home and the port is continuing to send its ships out to sea.
Port Hedland is Australia's biggest port and the biggest iron ore port in the world, shipping tens of millions of tonnes of iron ore a month from mines across the Pilbara to export markets, principally China.
Pilbara Ports Authority said it was also clearing anchorages and berths at the ports of Ashburton and Dampier.
Rio Tinto said the ports of Cape Lambert and Dampier were being cleared as a precautionary measure, and it was monitoring conditions for its other operations.
FMG CEO Elizabeth Gaines, whose company operates three iron ore minesites in the Pilbara, said conditions were being closely monitored.
"We have detailed cyclone preparedness procedures in place at all our operations in the Pilbara," she said in a statement.
BHP said all production had stopped at its Pyrenees oil field, which is about 20 kilometres offshore from the Northwest Cape.
Non-essential fly-in, fly-out staff from that operation and from Port Hedland have been sent home, with the last ships scheduled to leave the port today.
Yellow cyclone alert in place
Beaches in the area normally never have waves, but people have also been making the most of the swell generated by the advancing cyclone and surfing at point breaks and beaches across Port Hedland before the wind picks up.
A cyclone yellow alert is current for people between Pardoo and Mardie, including Port Hedland, South Hedland, Point Samson, Wickham, Roebourne, Karratha, Barrow Island and Dampier.
DFES said there was a possible threat to lives and homes as the cyclone approached, and residents needed to take action immediately.
A blue alert is current from Wallal to Pardoo and Mardie to Onslow, including Marble Bar but excluding Pardoo, Mardie, Pannawonica and Onslow in the Pilbara.
Although there is no immediate danger, those communities have been asked to start preparing, to secure or remove loose materials from around their homes and to ensure they have an emergency kit ready.
DFES Pilbara Superintendent Peter McCarthy has urged residents and visitors in towns in the Cyclone Veronica watch area to get ready.
"I encourage people to take notice, this is a big storm, it's very strong and unpredictable," he said.
"If anyone is visiting the area as a tourist now is the time to look at moving to Broome or to Carnarvon or Newman to get some distance.
"If you are vulnerable in caravans and camping, this is not the weather for that."
Main Roads has warned major flooding is expected along North West Coastal Highway and surrounding roads, and has urged travellers to avoid travelling north of Geraldton and south of Roebuck in coming days.
The highway is likely to be closed as the weather system intensifies, and drivers have been warned not to drive into water of unknown depth.ABC