By Colin Packham and James Regan

SYDNEY (Reuters) - Torrential rains were forcing residents and tourists to flee coastal areas along the Great Barrier Reef as the strongest cyclone in three years barreled across the Coral Sea for the Australian mainland.

Tropical Cyclone Ita is forecast by meteorologists to cross the coast near Cooktown on Australia's far northeast coast between 1100 and 1400 GMT.

Residents refusing to be evacuated to shelters or higher ground by emergency crews and police are being warned to hide in their bathrooms until the worst of the storm passes.

"We all can get through this without anyone being injured or killed," Queensland's Premier Campbell Newman said. "I want people to know you are not alone. We are all being backed up by a very big team."

Wind gusts of up to 300 kmh (186 mph) and widespread flooding are forecast through the weekend.

"While the strongest winds are focused near the center, the warning area for tropical cyclones of this intensity is quite broad with destructive winds, heavy rainfall possibly leading to flash flooding, and coastal inundation due to storm surge all posing a threat," said Rob Webb, Queensland regional director at Australia's Bureau of Meteorology

The storm's projected course should put an area stretching for 400 km (250 miles) at the greatest risk, emergency officials said.

The storm's erratic path makes pinpointing precisely where it will make landfall difficult, according to meteorologists.

People are being warned not to venture outside if they find themselves in the calm center, or eye, when the storm passes as very destructive winds from a different direction could resume at any time.

The storm was still classified as a tropical depression when it marched across the Solomon Islands late last week, killing at least 23 people near Honiara, the capital, according to the United Nations.

Sugar farmers in Queensland, who grow about 95 percent of the sweetener produced in Australia, are bracing for potential damage to up to 7 million metric tons of cane, industry groups said.

Australia, the world's third-largest exporter of raw sugar, has seen production devastated by cyclones in the past, driving up world sugar prices as buyers scramble for alternative sources of supply.

In 2011, Cyclone Yasi ripped through more southern parts of Queensland, destroying crops and causing over $3 billion in property damage and tourism business.

Before Cyclone Ita, sugar production in 2014/15 was forecast by the Australian Bureau of Agriculture and Resource Economics and Sciences to rise to 4.4 million metric tons from 4.2 million the previous year.

While the cyclone poses a threat to sugar, beleaguered cattle farmers may welcome widespread rain. Until now, drought has been forcing farmers to slaughter record numbers of animals as grazing land wilted.

The Great Barrier Reef, one of Australia's most popular tourist attractions, stretches more than 2,000 km along the Queensland coast and is the world's largest coral reef system.

The reef has lost half its coral cover in the last 27 years, with storms responsible for nearly half of that damage, the Australian government said in a 2012 report.

(Editing by Ryan Woo)