Tropical Cyclone Yasi

Tropical Cyclone Formation and Concerning Characteristics

Tropical cyclones are severe, spinning storm systems with low-pressure centres. Tropical cyclones form over warm waters between the two tropics: Tropic of Cancer (23.5°N) and Tropic of Capricorn (23.5°S). A tropical cyclone needs a warm body of water- at least 26.5°C - from which it gathers energy. This water must be at least 50m deep. The high temperature of the water means that evaporation is sped up. Once this water vapour hits the cooler atmosphere above, it encourages thunderstorm activity. The energy released in a thunderstorm starts circulating and is sucked upwards. The mid-troposphere (5km) must be relatively moist in order for the cyclone to develop. The heat energy combined with the rotation of the Earth (Coriolis force) gets the cyclone rotating and pushes it forward. Tropical cyclones cannot form spontaneously; these specific conditions are required.


What are hurricanes, typhoons and tropical cyclones?

Tropical cyclones are unbelievably destructive when they hit land. Their devastating winds and heavy rain cause substantial damage. Cyclone winds can reach up to 200 km/h and destroys anything in its path. The cyclone looks fierce from the outside, but its low-pressure centre (the eye), is deceptively calm. A dense wall of cloud surrounds the eye. When inexperienced people are in the “eye” they assume that the danger has passed and this makes the eye the deadliest part of a cyclone.


The large size of cyclones is a very concerning characteristic, as this causes severe, widespread damage. High winds with flying debris, storm surge, rain and flooding caused by a cyclone can affect thousands of people and inundate kilometers of land. These characteristics put lives at risk. Cyclones are rated in categories 1 to 5, with 5 being the most dangerous.



KGI Justification-

Movement- Tropical cyclones cause devastation to the environment in its path; trees are uprooted and flooding occurs as the cyclone hits the coastal areas. The wind and air are also moving.

Region- Cyclones can only occur in tropical regions. These regions are between the two tropics. This area is distinguishable to other places by its climatic conditions of hot temperatures and rain.

Distribution- Cyclones only form over water within the tropics of Capricorn and Cancer.

Spatial Association- There is a strong spatial association between the formation of tropical cyclones and specific latitudes and climatic conditions. The cyclones are located within 23.5°N and 23.5°S and have specific climatic conditions in which they will form.

Location- Tropical cyclone form over oceans.


Pathway of Cyclone Yasi


Cyclone Yasi started developing as a tropical low 330km off the northwest of Fiji on the 26 January 2011. When it intensified and was classified as a tropical cyclone, it was located approximately 370km northeast of Vanuatu. Cyclone Yasi rapidly intensified into a category 5 system as it went through another tropical low. Yasi maintained its intensity and its west-southwest movement, towards the tropical Queensland coast, between Cairns and Townsville. It hit land near Mission Beach early on Thursday 3rd February 2011. Being such a strong and large system, Yasi maintained a strong core with damaging winds and heavy rain, tracking westwards across northern Queensland. Yasi finally weakened to a tropical low near Mount Isa.


Since the route for Cyclone Yasi was about 2400km of warm water, it quickly built up lots of energy and intensity. Once Yasi hit land, it was a giant wall of wind and rain, charged by its prolonged journey over tropical waters. This meant that once it hit land it took a long time to weaken into a tropical low and was very destructive.


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KGI Justification-



Location- Cyclone Yasi started developing as a tropical low 330km of the northwest of Fiji. It hit land near Mission Beach, which is an example of an absolute location.

Movement- The path of cyclone Yasi was 2400km as it travelled from Fiji (as a tropical low) to the Australian coastline near Mission Beach.

Spatial Interaction- Cyclone Yasi developed into a category 5 system when it interacted with another tropical low and therefore intensified the system dramatically.

Scale- Cyclone was rated as a category 5 cyclone, which is the highest rating on the scale.


Characteristics of Cyclone Yasi

The main characteristics of cyclone Yasi that devastated part of Queensland were the torrential rain, strong winds and storm surge. Cyclone Yasi brought an average of 200-300 ml of rain in 24 hours and caused widespread flooding. The highest total was in Mission Beach, where 471 mm was recorded to have fallen within 24 hours. The average rainfall for Queensland in one month is 160 ml. Thousands of homes were inundated due to the heavy rainfall.


Strong winds are a typical characteristic of cyclones. Cyclone Yasi was estimated by the Bureau of Meteorology to have winds that reached up to 285 km/h and flattened everything in its path. Homes were ripped apart, roofs torn off, power and communications cut and crops flattened. Many trees fell onto houses and roads. Up to half the homes in the town of Tully were severely damaged.


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A storm surge is the elevation of the ocean water surface occurring as a result of force of extreme winds and the inverse barometric effect associated with low pressure systems, particularly tropical cyclones. The government’s extensive network of 25 storm tide gauges and 14 wave measuring buoys strategically located along Queensland’s coastline provided technical information that was used to identify the storm tide threat and extreme waves. After Cyclone Yasi had made landfall, scientists began surveying the impacts along 230 kilometres of coastline in the worst-hit areas from Townsville to Bramston Beach. In Mission Beach a storm surge estimated to have reached 7 m along the coast and pushed 300 m inland. Most of the beach had lost its sand and every structure was damaged to some extent. The storm surges left thousands of houses inundated along the coast. Many objects including boats are picked up and moved onto the land due to these surges.


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KGI Justification-


Scale- The devastation of cyclone Yasi was large scale as it impacted on 230km of coastline.

Location- A number of absolute locations have been mention in relation to being affected by cyclone Yasi. These include Townsville, Mission Beach and Bramston Beach.

Distance- Cyclone Yasi severely impacted on the area between Townsville to Bramston beach, some 230km of coastline.

Movement- The tidal surge is an example of movent of the ocean that travelled 300m inland and rose 7m.

Spatial Change over Time- As a direct result of cyclone Yasi, towns were virtually uninhabitable because of damaged homes, lack of power and communication and crops flattened. This all happened in a matter of hours.


Cyclone Yasi's Affect on Natural and Cultural Landscapes

Parks and rainforests (including the Daintree) in Queensland suffered substantial damage. There was immense tree loss and canopies were stripped of leaves. Luckily rainforests have been able to adapt to extreme weather events. The fast growing pioneer trees that protect inner, old-growth rainforest were battered beyond recognition. Their purpose appears to be to take the brunt of the storm and in this way, protect the old growth.


One of the most concerning impacts of Cyclone Yasi was habitat destruction of the already endangered southern cassowary. Loss of the canopy fruit caused a shortage of food and forced the cassowary out of the safety of their homes. In search of food, the southern cassowary population found their way into the danger of land occupied by humans. Yasi also caused severe damage to the habitat of mahogany gliders. The gliders were already limited to a strip of lowland sclerophyll forest between Townsville and Tully. This threatened the mahogany gliders even more.

The cultural landscape sustained severe damage by cyclone Yasi. Homes were ripped apart, roofs torn off and power and communications cut. 150 houses were destroyed and another 650 were unliveable. 2275 homes sustained moderate damage and at least 200000 homes lost power. This severely affected tourism as Mission beach is a popular tourist destination, especially over the winter months.


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KGI Justification-


Region: Cyclone Yasi affected the coastal and tropical rainforest regions. It also impacted on urban regions affecting industries such as tourism.

Distribution- The southern cassowary and mahogany gliders are endangered species and are distributed over a small amount of the rainforest areas within northern Queensland.

Movement- The southern cassowary moved into the suburbs in search of food.

Spatial Association-

Spatial Change Over Time- The animals habitat has been destructed within hours of cyclone Yasi hitting the mainland. The rainforest is able to regenerate over time.


Two Effects of Cyclone Yasi

Banana Plantations-


Cyclone Yasi has had a huge impact on the banana plantations in far north Queensland. This region provides 90% of Australia’s bananas. Cyclone Yasi, with its strong winds flattened 75% of the crop and devastated the Banana Industry. The Tully and Innisfail Plantations, which grow the majority of Queensland bananas, were hit worst. The impact of Cyclone Yasi, sent banana prices from $1.98 a kilogram to $15 a kilo. This was a rise of rose 470%. It took about 12 months for the industry to get back to full production.


The two most affected plantations were Tully and Innisfail, which provide 90% of Australia’s bananas. This meant that the places that would be affected would be the whole of Australia (as 90% of the bananas were produced in this region) and international places such as the Philippines. These places were left with a shortage of bananas and very high prices. The high rise in prices meant that many consumers took bananas off their shopping list. Obviously this then impacted the already struggling farmers, as they had to source an income because their livelihood had been diminished in a matter of hours.


Insurance Prices-


Insurance premiums were also increased due to cyclone Yasi. There were 71,145 insurance claims due to Cyclone Yasi and reached an estimated total amount of $1.4 billion. The price of insurance rose 30% in early 2012 due to “extreme weather” conditions. These weather disasters also included the Brisbane floodings. Shares in Brisbane-based insurer Suncorp fell more than 1.5% in a matter of days from when Cyclone Yasi hit. Insurance company Swiss Re said that “Australia has become a riskier place to do business due to the string of natural disaster since 2009”. Insurance premiums Australia-wide were rising in the aftermath of Cyclone Yasi. This means that the victims of Yasi as well as people who were not affected but had insurance with the companies involved, had to pay more. This means that someone who needed to claim on damage to their house in places other than northern Queensland would need to pay more.




KGI Justification-


Scale- The plantations of bananas were largely located in the area hit by cyclone Yasi but the impact on the prices and distribution was on a national and global scale.

Distribution- Bananas are mainly grown in northern Queensland. People were affected by the increase in insurance premiums across Australia.

Movement- As a result of cyclone Yasi, the movement of the trade in bananas was severely impacted as most of the banana crops were damaged.

Spatial Association- The link between the price of bananas and the devastation of the crops. When natural disasters occurs insurance premiums rise.


Changes for the Region and for Wider Australia due to Cyclone Yasi

There have been many changes that have occurred to the affected region and wider Australia due to Cyclone Yasi. The Queensland Government has adopted a new policy for more strict building regulations in cyclone prone areas. The regulations are in place to protect infrastructure from damage from winds and storm surges. This includes specific building materials, roof covering, tie downs, bracing, fences and stronger windows and doors to improve debris protection. The Government also proposed a flood levy because of the damage left from cyclone Yasi and the Queensland flooding, which was just beforehand. These regulations aim to prepare the regions for tropical cyclones and minimise damage clean up and costs.



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The regulations for the locations of structures has also been changed because of the impact of Cyclone Yasi. Houses, telephone poles and other infrastructure must be approved for their location by undergoing wind speed tests. It was noticed that the structures on hills (where wind speeds are greater) were ripped out of the ground during Cyclone Yasi. Houses in low lying areas are prone to flooding and must now be built on stilts to reduce inundation.


As for the rest of Australia, some States designed their own natural disaster guidelines to help reduce cost and damage from natural disasters including bushfires, flooding and cyclones. The prices of fruit (especially bananas) also rose dramatically. Even when the farms were back to full supply the prices were still higher than beforehand to make up for lost income.


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