By Renju Jose

SYDNEY, Feb 14 (Reuters) - Australia's iron ore export hub, the world's largest, braced on Friday for a powerful tropical cyclone, forcing the closure of all of the major commodity ports in the country's northwest as residents rushed to stock up on essential supplies.

Cyclone Zelia, located in the Indian Ocean about 115 km (72 miles) north of Port Hedland, has been upgraded to a category five storm, the highest rating on the scale, Australia's weather bureau said in its latest warning note.

The system is expected to make landfall on Friday evening near Port Hedland in the Pilbara region, packing wind gusts of up to 320 kph (200 mph) and bringing heavy rains across a 550 km sparsely populated stretch, the weather bureau said.

"We haven't seen the worst of the weather yet but we've already started to see the rainfall numbers tick up and some strong wind gusts along the coast," forecaster Angus Hines said.

Port Hedland's port, the world's biggest iron ore export point, was closed on Wednesday, while the ports of Dampier and Varanus Island, a gathering and processing hub for oil and gas, were shut down on Thursday evening. Cape Lambert was also shut.

Port Hedland is used by BHP Group BHP.AX, Fortescue FMG.AX and billionaire Gina Rinehart's Hancock Prospecting, while the Dampier and Cape Lambert ports ship iron ore from Rio Tinto RIO.AX.

The potential disruptions to supply from Western Australia did not impact Dalian iron ore futures on Thursday, which snapped a two-day rise amid concerns over the U.S. steel tariffs and potential Indian taxes.

Iron ore is the primary raw material used to make steel.

Port Hedland's 15,000 residents, most of whom are mining company employees, have been advised to seek shelter indoors, while non-essential staff have been moved to safe locations.

Some supermarkets have been closed, ABC News reported, after essential supplies ran out as people stocked up.

(Reporting by Renju Jose in Sydney; Editing by Jamie Freed)

((renju.jose@thomsonreuters.com;))