Tropical Cyclone Lam has strengthened to a category four system as it passes near to Elcho Island where several thousand people are sheltering without power.

Winds are gusting at 230 km/h as the system moves towards the Northern Territory mainland.

Earlier on Thursday, 430 people from the Aboriginal community of Warruwi on Goulburn Island were evacuated to Darwin on helicopters and planes.

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Eighteen small planes and two helicopters have been shuttling between Warruwi and Darwin, about 300km southwest, and by early afternoon on Thursday about half the people had arrived at the emergency shelter at the Darwin Showgrounds.

The Bureau of Meteorology (BoM) has advised it expects the cyclone will cross the NT’s mainland coast between Milingimbi and Gapuwiyak early on Friday morning.

Forecaster Ben Suter said Elcho Island was currently bearing the brunt of the cyclone.

“Residents should be bunkered down in safe housing at the moment.” he said.

More than 400 people have been evacuated from Goulburn Island. Photo: ABC

“The next concern is, as the cyclone moves closer to land on the south-west trajectory and then mainland, locations and communities between Milingimbi and Elcho Island will be next in line as we move into the overnight period.”

This comes as Tropical Cyclone Marcia is threatening Queensland’s coast, which is expected to make landfall at a destructive category five system, early Friday morning.

Up to 5,000 people in remote Arnhem Land Indigenous communities have so far been directly affected by the cyclone, authorities have said.

NT Chief Minister Adam Giles said the evacuation from Warruwi was proceeding well and necessary to ensure the safety of residents.

“At this stage it is a very well structured risk-management process,” he said.

Residents urged to take shelter

Remote communities are predicted to be hardest hit, with Cyclone Lam set to make landfall at Nhulunbuy and Elcho Island in Arnhem Land, 1000km from Darwin.

Residents have been advised to take shelter immediately, with flood warnings in place for coastal areas.

Evacuees fleeing Cyclone Lam at the Darwin show grounds shelter. Photo: AAP

Late Thursday afternoon Elcho Island had lost power and water supply as strong winds herald the arrival of the cyclone.

NT residents in older community housing have been encouraged to relocate to shelters at the local school and Marthakal Aboriginal Corporation workshop.

Both are housing approximately 400 people and are being manned by local teachers and volunteers.

Northern Territory police said arrangements were in place to evacuate the 350 people living on Goulburn Island to Darwin.

Meanwhile, there are additional concerns for the nearby communities of Gapuwiyak and Milingimbi.

A storm surge is predicted to coincide with a very high tide on Friday morning, which could create serious flood damage for these low-lying communities.

Social media users have already begun sharing photos from inside storm shelters.

Australia is about to be hit by two cyclones at once. #CycloneLam in the north and #CycloneMarcia off the east coast pic.twitter.com/FSPEGxEEfJ

— David Wyllie (@journodave) February 19, 2015

All houses in #Maningrida not up to cyclone standard have been evacuated #CycloneLam — Steven Schubert (@senorschubert) February 19, 2015

AUSTRALIAN MUSIC STAR GEOFFREY ‘GURRUMUL’ YUNUPINGU HAS BUNKERED DOWN FOR #CYCLONELAM http://t.co/eUyClt7OvN pic.twitter.com/NtXmz17Qqy — The NT News (@TheNTNews) February 19, 2015

Thanks to @kookarelli for this great pic taken in #Yirrkala #CycloneLam pic.twitter.com/d7SWsvhtYV #TopEnd — Top End Tweets (@TopEndTweets) February 19, 2015

Peanut butter sandwiches for lunch at #ElchoIsland shelter as community awaits #CycloneLam pic.twitter.com/72TnhrOydO — Felicity James (@james_felicity) February 19, 2015

Emergency meeting in #Maningrida as #CycloneLam approaches @abcnewsNT pic.twitter.com/5npBKfFItu — James Oaten (@james_oaten) February 19, 2015

Inside a #CycloneLam shelter on Elcho Island. Shelter chef Ollie Hokema just cooked breakfast for 200 people. pic.twitter.com/ExXySrJGpm — 105.7 ABC Darwin (@1057darwin) February 18, 2015

Another one of Middle beach in #Nhulunbuy from Tim Bunton. #cyclone lam pic.twitter.com/bJAHlTGBLU — Steven Schubert (@senorschubert) February 18, 2015

Amazing photo taken by Anthony Say of the storms coming of cyclone Lam pic.twitter.com/CLpxRF83sl — *Jezebella * jessie (@JessiStreet) February 18, 2015

If this is Cat 3 from a distance, I just can’t imagine a direct hit Cat 5. #CycloneLam #Gove pic.twitter.com/aItlCR1rHA — Zachary Hope (@Zhope10) February 18, 2015

Wind intensity building in Nhulunbuy. Bakery, Woolies and Petrol station have opened for a couple of hours. Champions. Stay safe #CycloneLam — Iapetus (@Iapetusmoon) February 17, 2015

Looking NE from Elcho Is barge landing across a choppy Cadell Strait, the edge of Cyclone Lam in view. #CycloneLam pic.twitter.com/fkvw1BhwAa — Jazlie DavisGrygoruk (@Jazlie) February 18, 2015

– with ABC