Cyclone updates are constant, and always monitored. A tropical cyclone is “a tropical low pressure system intense enough to produce sustained gale force winds (at least 63 km/h)” as defined by BOM's resources on cyclones. Cyclones aren't necessarily like those picturesque "fantasy" twisters seen in Hollywood films. They generally tend to be very fast winds which uproot trees, topple over power poles and destroy property roofing.
In the average cyclone season, roughly 10 cyclones will develop over Australian-monitored waters, and roughly 6 will cross the coast and hit the northern half of Australia. This is because of the El Nino and the La Niña. Scientists have proven that occurrence of the El Niño increases cyclone activity in the Atlantic, whilst the La Niña provokes cyclone formation in the pacific.
This chart shows where the most common occurrences of cyclones take place over Australia on an annual basis.
East coast lows are a phenomenon that takes place on the eastern coast of Australia. These occur outside of the tropics zone, but can still almost match the power of a cyclone. They form when there is a high pressure system towards the southern coastal area and a low directly above around Queensland. These systems draw moisture from the Tasman Sea, and can cause violent rain and flooding in NSW or QLD. With the intense low near Queensland, this weather pattern can further push other aggressive storms into action.
Australia uses a separate system to the U.S. for measuring the severity of cyclones. Accordingly, the risk of property and crop damage, shore erosion and danger to life is all taken into account with the scale, ranging from 1-5 (one being the weakest).
- Category 1 - associated with minimal house damage, and minor damage to crops, caravans, trees and moorings
- Category 2 - associated with Minor house damage, significant damage to trees, signs and caravans. Heavy damage to some crops, risk of power failure and small craft may break moorings.
- Category 3 - associated with some roof and structural damage to housing. Caravans can possibly be destroyed and power failure likely to occur.
- Category 4 - associated with significant roofing loss and structural damage to housing. Many caravans are likely to be either destroyed and/or blown away. Dangerous airborne debris and widespread power failure is also highly likely.
- Category 5 - associated with extremely dangerous wind with widespread and malicious destruction.
The BOM will issue a warning to areas of Australia under threat of a tropical cyclone using this category system. This helps the public to prepare their houses and surroundings to minimise damage from loose roof tiles or falling branches. The damage factor varies from location to location based on how far you are from the zone of maximum cyclone winds, how exposed the location is the quality of the building/house, crop type and planting and flooding. All these factors determine how much damage a cyclone will have in an area.
The Economic, Social and Environmental effects of Tropical Cyclones
The two most costly hazard types for each State and Territory are:
- New South Wales (floods, storms)
- Queensland (floods, tropical cyclones)
- Victoria (floods, bushfires)
- Western Australia (tropical cyclones, storms)
- South Australia (floods, storms)
- Tasmania (bushfires, floods)
- Northern Territory (tropical cyclones, floods)
- Australian Capital Territory (bushfires, storms)
From this information we can see that for three out of eight states, tropical cyclones were one of the most costly for the country. Including cyclones, six out of eight states and territories blamed storm activity as the most costly natural hazard. On an annual basis, cyclones can cause up to 2.5 billion worth of damage in Australia. This affects the socio-economic status of some of the victims of tropical cyclones.
In a severe tropical cyclone, people can lose just about everything; an example of this was the victims of cyclone Tracy. This majorly affects their sociality with people around them as many grieve for the loss of their homes or even lives. One single devastating cyclone can change the outlook on some people's lives depending on what damage was done to them, be it physically, mentally or materially.
It is an understatement to say that the environmental effects of cyclones are devastating. Flash flooding ruins crops and pollutes dams/water supplies. Excessive rain causes runoff from mountains and speeds up erosion, as well as wind which erodes and sucks up loose rubble from anywhere. Associated storm tides along with wind quickly erode down beaches and rock faces along the coast. The debris from houses and elsewhere fly through the air like sharp, jagged blades which cuts up anything in its path, along with dirt and dust which is sucked up into the clouds along with other naturally forming chemicals to produce acid rain. Fires can start amidst all the chaos if a sub-station blows up. Tropical cyclones are possibly one of the most devastating natural disasters to affect the environment, so it's best to follow guidelines set out by the government to help protect the environment.
Responsibility to the hazard at an individual, community-based and Government level
There are many suggested courses of action to take once a cyclone warning has been issued by the government. The BOM suggests checking to see if your house is cyclone protected, and if it isn't, steps should be considered to cyclone-proof the house. Check all the walls, roofing tiles and eaves at the house, and patch up gaps. Trim treetops and branches well from your house, so little debris as possible hits your house. It is best to know where the nearest high ground is, in case of flooding. Glass windows should be reinforced with wire shutters or mesh to prevent shattering. Another helpful suggestion is to prepare an emergency kit if needed for a quick evacuation.
On a community level, organisations in cyclone affected areas of Australia provide detailed and helpful information about how to help you before and when a cyclone hits, but also provides places of refuge, such as a local community centre or town hall.
The government weather service (BOM) is responsible for monitoring and warning the Australian public about incoming cyclones. The government also provides money to the badly affected victims after the cyclone to help them rebuild their lives. The Bureau of Meteorology also has a 24 hour information hotline regarding tropical cyclone information and assistance.
