By James Regan
SYDNEY (Reuters) - A pair of tropical cyclones was bearing down on northeastern Australia on Thursday and emergency officials warned residents to take shelter ahead of torrential rain and flooding, destructive winds and massive seas.
Cyclone Marcia off the northeast coast of Queensland state is forecast to dump 300 mm of rain in the next 24 hours, with wind gusts up to 90 kph (55 mph), making it possibly the most destructive cyclone to hit Queensland since 2013.
The more powerful Cyclone Lam, with winds expected up to 130 kph (80 mph), was heading west towards the Northern Territory and had already forced some 350 residents to evacuate exposed offshore islands.
"Our message to Queenslanders is start getting ready now," said state premier Annastacia Palaszczuk. The worst of the storms are expected to hit on Friday.
Shipping and aluminum smelting in the path of the cyclones could face disruptions but farmers suffering under severe drought will welcome the soaking rains.
The Port of Gladstone, Queensland's biggest multi-commodity port handling much of the state's coal, alumina, bauxite and natural gas shipments, said it was monitoring Marcia's movement and following procedures in place to deal with storms.
Maritime Safety Queensland said ships would be moved away from Gladstone Harbour and into deeper, safer sealanes as a precaution, the Australian Broadcasting Corp. reported.
Data supplied by the Bureau of Meteorology shows Marcia making landfall roughly 125 km (75 miles) north of Boyne Island in Queensland, where Rio Tinto operates Australia's largest aluminum smelter.
Rio Tinto said it was also monitoring Lam given its proximity to the company's Gove bauxite mining operation in the Northern Territory. Lam was also threatening to disrupt BHP Billiton's Groote Eylandt manganese mine and Glencore's (GLEN.L) McArthur River zinc and lead mine.
Queensland State Emergency Services said it had so far handed out more than 7,000 sandbags to help shore up homes and storefronts and advised residents to seek higher ground to ride out the storm.
Marcia had intensified quicker than expected, strengthening from a tropical low in the Coral Sea into a cyclone by Wednesday evening, according to meteorologists.
"This is a fast-moving system, so we expect a lot of rain in a short time-frame," Queensland Fire and Emergency Services acting commissioner Katarina Carroll told reporters.
Coastal towns were already feeling the brunt of rising seas, with destructive waves and the highest tides of the year expected to cause widespread coastal flooding. Many beaches were closed.
"The seas will be big, the swells will be big, the winds will be strong, and the rain will be very, very heavy," said Maritime Safety Queensland spokesman Patrick Quirk.
"You'd be a very brave or foolish seafarer who went to sea in these conditions unless it was an urgent or lifesaving issue."
(Editing by Michael Perry)