Tropical cyclones (also known as hurricane in North America and typhoons in Asia) are giant whirlwinds of air and dense cloud spiraling at over 120 km/hr around a central ‘eye’ of extreme low pressure.

Australia’s cyclone season is usually from December to April and affects most of the Queensland coast. The greatest threat lies north of the Tropic of Capricorn.

When a tropical depression develops and its associated winds reach gale force, it will be classified as a tropical cyclone and will be given a name.

Cyclones occur frequently in the Southern Hemisphere with an average of 10 cyclones per year tracked by the Bureau of Meteorology in the Australian region.

The ‘life-cycle’ of the average tropical cyclone is about seven days, but can extend to over three weeks.

Cyclone watch

A cyclone watch is issued by the Bureau of Meteorology when a cyclone or developing cyclone is likely to affect coastal or inland communities within 24 to 48 hours.

A cyclone watch will include an estimate of the cyclone’s position, its intensity, severity and movement.

Cyclone watches will be issued every three hours initially and hourly once the cyclone nears the coast.

Cyclone warnings

A cyclone warning is issued by the Bureau of Meteorology when a cyclone or developing cyclone is likely to affect coastal or inland communities within 24 hours.

Warnings will identify the communities likely to be affected, the name of the cyclone, its position, intensity, severity and movement.

Communities under threat will be advised to take certain precautions to safeguard life and property.

Cyclones often produce winds in excess of 200 km/h which can cause extensive damage to property and turn debris into dangerous missiles.

Cyclones can also bring flooding rains, which cause further damage to property, and increase the risk of drowning.

Cyclones can cause huge seas, putting vessels in danger both in harbor and out at sea.