Australian Tropical Cyclones

Tropical cyclones (or hurricanes in North America, typhoons in Asia) are like giant whirlwinds of air and dense cloud spiralling at over 120 km/h around a central eye of extreme low pressure.

Cyclone Season and Effects

Australia's cyclone season is usually November to April. Cyclones mainly affect coastal areas north of Perth along the WA and NT coasts, most of the Queensland coast and occasionally the far northern NSW coast. The greatest threat lies north of the Tropic of Capricorn.

Frequency

Cyclones occur frequently in the southern hemisphere, with an average of ten per year being tracked by the Bureau of Meteorology in the Australian region alone. Of these, six may be expected to cross the Australian coast each year. Cyclones further out in the Indian and Pacific Oceans are monitored in case they threaten Australian islands or nearby countries.

Severity Categories

• 1 weak cyclones, wind gusts less than 125 km/h
• 2 wind gusts from 125 to 169 km/h
• 3 wind gusts from 170 to 224 km/h
• 4 wind gusts from 225 to 279 km/h
• 5 severe cyclones, wind gusts more than 280 km/h

Effects

Cyclones approach from the sea bringing with them torrential rains, extreme winds and sometimes storm surges. Damage caused by each cyclone varies widely depending on its path, but can include buildings, crops and boats at sea. Most deaths from cyclones occur as a result of drownings (both at sea and during floods), collapsed buildings, or debris which become lethal projectiles carried along by the extreme winds.

Cyclone Survival and Property Protection

In cyclone-prone areas of Australia, strict building codes exist for all new constructions. In some areas public cyclone shelters are provided in strong buildings for people who live or work in sub-standard buildings. A cyclone warning system is provided by the Bureau of Meteorology, and State and Territory Emergency Services run preparedness campaigns to support community emergency plans. If you live in a cyclone-prone area you should heed this advice:

Before the Cyclone Season

• Know your community cyclone plan, and how the cyclone warning system works.
• Have a portable radio and torch with spare batteries.
• Check that your house is in good condition, particularly the roof, and trim tree branches clear of your house. Clear property of loose items likely to cause damage in high winds.
• In case of a storm surge warning, identify your nearest safe, high area in advance.
• Create an emergency kit of tinned food, water containers,emergency lighting, first aid kit, medicines, tape and plastic bags.

Upon a Cyclone Warning

• Listen to your local radio or TV for further warnings.
• Board or tape windows, store loose articles inside.
• Lock up pets, fill water containers, fuel car and place under cover.
• Check your emergency kit and put spare clothing and shoes in plastic bags.

On Warning of a Local Evacuation

• Switch off electricity, gas, etc. and lock your house upon leaving.
• Don't forget your emergency kit. Follow instructions from emergency personnel.

When the Cyclone Strikes

• Stay inside and shelter in the strongest part of the house e.g. the bathroom or cellar.
• Protect yourself with mattresses, blankets and anchor yourself to a strong fixture (such as water pipes) or get under a strong table.
• Beware the calm eye of the cyclone. Remain indoors until advised that the cyclone has passed.

After the Cyclone

• Don't go outside until advised officially that the cyclone has passed.
• Listen to your radio for further information and advice.
• If you had to evacuate, don't go home until advised. Use only recommended routes.
• Beware of fallen power lines, damaged buildings, trees and flooded water courses.