Cyclone Yasi – A Category 5 Cyclone -the Largest Cyclone In Queensland’s History

Australian Cyclones

Cyclone Yasi was the most intense Cyclone and tropical storm to ever strike the Queensland coast in recorded history. A strong La Nina was in effect in the year 2011 and aided in the development of Yasi

Severe Tropical Cyclone Yasi was an intense and destructive tropical cyclone that made landfall in northern Queensland, Australia, in early 2011, causing significant destruction to the affected areas.

Starting as a tropical low near Fiji on 26 January, the system strengthened to tropical cyclone status throughout the night of 30 January. Yasi deepened swiftly over the following 24 hours and was assessed as a Category 3 cyclone at around 5 pm AEST (07:00 UTC) on 31 January 2011. Late on 1 February, the Cyclone intensified to a Category 4 system; then, early 2 February, the Cyclone strengthened into a Category 5 Severe Tropical Cyclone.

The system had a well-defined core & proceeded to trace west-southwestward, sustaining a central pressure of 930 hPa (27 inHg) & a Dvorak intensity of T6.5 into the evening.
At about midnight AEST (14:00 UTC) on 3 February, Yasi passes over the Australian coastline as a Category 5 severe tropical cyclone close to Mission Beach, with an estimated maximum of 3-second gusts of 285 km/h spanning a region from Ingham to Cairns.

A record low of 929 hPa (27.43 inHg) was measured because the eye passed over Tully. Thanks to the system’s scale and its strong core, Yasi maintained cyclonic intensity farther inland than expected, eventually dissipating into a tropical low near Mount Isa at 10 pm on 3 February 2011, 22 hours after the storm first converged on the coast.

The storm generated an estimated AU$3.5 billion (US$3.6 billion) in damage, making it the most costly tropical Cyclone to hit Australia on record (not accounting for inflation; otherwise, Cyclone Tracy was costlier). Yasi was also indirectly to blame for the death of a 23-year-old man, who died from suffocation by generator exhaust.

Cyclone Yasi – A Category 5 Cyclone -the Largest Cyclone In Queensland’s History

Tropical Cyclone Yasi was the largest storm in Queensland‘s history, with more than 10,000 souls moved from their houses. The storm passed between the two big towns of Cairns and Townsville, which only suffered minor damage. Early estimations of the structural damage caused put the value at about AU$100 million.

It didn’t cause the maximum amount of damage as the government expected because it missed significant cities. It did, however, destroy 30% of the homes in Tully. At least 75% of the banana harvest was destroyed, including damage to the sugar cane farms was anticipated to cost about AU$500 million. Destruction to power lines left 150,000 homes without electricity.

How Cyclone Yasi Formed

Tropical Disturbance 09F was initially identified on 26 January 2011 by the Fiji Meteorological Service (FMS), while it had moved 330 km (205 mi) south-southwest of Tuvalu. Over a range of high sea surface temperatures & low to moderate wind shear, it had been expected to strengthen gradually because it moved southwest. Little development happened over the subsequent two days, though it had been classified as a tropical depression on 27 January.

By 28 January, the tropical depression was characterised as a poorly-developed low, with a broad area of rotating, flaring convection. Considerable development happened on a subsequent day, urging the Joint Typhoon Warning Center (JTWC) to announce a Tropical Cyclone Formation Alert. The storm’s low-level rotation centre became more defined, and convective banding characteristics were apparent along the northern periphery of the tropical depression.

It deepened rapidly throughout 30 January, leading to the JTWC upgraded the tropical system to a tropical storm following data from an ASCAT image pictured winds near gale-force around the storm’s centre. Shortly after that, the FMS also promoted the storm, classifying it as Tropical Cyclone Yasi.

Cyclone Yasi – A Category 5 Cyclone -the Largest Cyclone In Queensland’s History

Upon being labeled a tropical cyclone, Yasi was located about 370 km (230 mi) northeast of Vanuatu. Along the northern fringe of a powerful subtropical ridge, the storm generally tracked westward, taking it through the country’s northern islands. Continuing to intensify rapidly, Yasi attained severe tropical cyclone intensity with ten-minute sustained winds of a minimum of 120 km/h (75 mph) on 31 January because the principal convective belt wrapped around the storm’s centre.

Later that day, the Cyclone crossed 160°E, prompting the final advisory from the FMS and, therefore, the first advisory from the Australian Bureau of Meteorology because the system crossed into the Australian cyclone basin.

(above) Tropical cyclone Yasi rain radar loop – you can see in the above radar loop how the Willis island radar and measurement instruments were destroyed as the cyclone approached, then the Queensland coastal radar started capturing the intense tropical storm.

Cyclone Yasi Preparation, Impact & Aftermath.

Severe Tropical Cyclone Yasi directly struck the Solomon Islands, Vanuatu, & parts of Australia, while sections of Fiji and Papua New Guniea were indirectly affected. As a result of the system’s collisions, the name Yasi was subsequently withdrawn from the record of South Pacific tropical cyclone names & replaced with Yvone.

Fiji, Vanuatu, Papua New Guinea, and also the Solomon Islands

Between 23–30 January, powerful winds and swells were witnessed in Tuvalu as Tropical Cyclones Wilma and Yasi formed and crossed. These powerful winds limited shipping schedules and affected students studying in Vaitupu and Fiji, and outer islands ran out of fresh supplies due to rough seas. During 28–30 January, Yasi’s precursor tropical depression produced rain and powerful winds over the Fijian islands off Rotuma, Vanua Levu, Taveuni, and therefore the northern Yasawa Islands.

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On 30 January, Yasi became the second of three systems to impact Vanuatu in two months directly. Tropical Cyclone Yasi passed over Vanuatu’s northern Torba Province, with winds reaching 95 km/h (60 mph). Vanuatuan officials reported difficulties in contacting the Torba Province, but it had been believed that the northern area escaped significant damage.

Cyclone Yasi – A Category 5 Cyclone -the Largest Cyclone In Queensland’s History
Cyclone Yasi Track Map 2011

The storm was several hundred kilometres southeast of Papua New Guinea, although the massive system’s exterior edges produced strong gales, high seas, & heavy rainfall to the nation. In Milne Bay Province, local administrators advised residents living along the coast to maneuver to higher grounds.

Willis Island

As Yasi passed into the Australian region, meteorological data from the meteorological observation post on Willis Island was used to help observe the system. Before the system impacting the island, staff battened down the buildings and were evacuated off the island by a helicopter on 1 February. Yasi subsequently passed directly over the meteorological observation post on 2 February.

Wind gusts of 185 km/h (115 mph) & a minimum pressure of 937.9 hPa (27.70 inHg) were registered before the meteorological equipment & connections failed. Following the system passing over the island, it became clear that the strong winds and storm surge had damaged the radar, critical observing systems also as communications, operational and life support infrastructure.

It had also been noted that the system had altered the structure of the island & cleared most of its vegetation.

Most of the automatic surface observing systems & communications were consequently restored & have become operational, fifteen days following Cyclone Yasi had passed over the island.

Cyclone Yasi – A Category 5 Cyclone -the Largest Cyclone In Queensland’s History

However, the weather radar and life-supporting systems took a touch longer to revive & were consequently completed by the end of November, before the crew returned to the island during December 2011.

Australia

By the time Yasi crossed into the Australian basin, preparations for the storm were underway. Media outlets mentioned the storm as “what may well be the state’s worst cyclone in history.”

Because of its vast size, many feared that the tropical Cyclone could cause damage exceeding severe Cyclone Larry in 2006 or Cyclone Tracy, which seriously damaged Darwin in 1974. Thousands of inhabitants within the path of the storm were urged to relocate by Queensland Premier Anna Bligh. Thirty thousand people were relocated from Cairns, including all patients from Cairns Base Hospital and Cairns Private Hospital.

They were airlifted by the Royal Australian Air Force and other agencies (such because the Royal Flying Doctor Service – RFDS) to Brisbane. The Queensland state emergency coordinator advised residents that they might be on their own for up to 24 hours because the circumstances would be too dangerous for emergency responders.

Waves as high as 12 m (39.37 ft) were predicted to strike the north Queensland coast because of the storm surge caused by Cyclone Yasi combined with a tide of up to 7 m (23 ft) above average.

Cyclone Yasi – A Category 5 Cyclone -the Largest Cyclone In Queensland’s History

In Mission Beach, near where Cyclone Yasi struck, wind gusts were estimated to have reached 290 km/h (180 mph), leaving much damage. A storm surge estimated to reach 7 m (23 ft) collapsed several structures along the coast & pushed up to 300 m (980 ft) inland to the interior. Within the hours after the storm’s passage, police couldn’t venture beyond their station grounds because the situation had yet to be declared safe.

Most of the exposed beach had lost its sand, and each structure was damaged to some extent. Near sunrise on 3 February, there have been no reports of fatalities or injuries in Mission Beach. Because the storm’s eye moved over several towns in Queensland, news reporters took the chance to provide brief damage assessments before the eyewall returned. Tully, Silkwood, Tully Heads, Mission Beach, Innisfail, and Cardwell were the worst affected areas.

According to inhabitants in Tully, the town was “…a scene of mass devastation”.

An unknown number of houses were completely destroyed as intense winds, estimated at 209 km/h (130 mph), battered the region. Many other dwellings not destroyed sustained severe facade and or roof destruction. As the dawn and daybreak came, reports from the city stated that about 90% of the structures along the main avenue sustained extensive damage.

Downed power pole & lines on Kings Road In Townsville

An evacuation point in Innisfail began to flood because the worst of Yasi’s impacts neared. Evacuees were reportedly hammering boards at the base of doors to stop water from further entering the structure. Additionally, concerns over the building’s windows occurred as they flexed amidst winds over 200 km/h (120 mph).

In Townsville, numerous roofs were torn off buildings & sent hurtling down the streets. Many windows are believed to have been broken & damaged as residents reported the sound of glass breaking throughout the night because the storm moved through. In Tully, the high school was destroyed and was rebuilt.

Numerous emergency calls were made by residents trapped in their houses near the peak of the storm. However, their calls couldn’t be acted upon as conditions were too dangerous for police to travel in. One reported instance was six people trapped in an apartment complex at Port Hinchinbrook near Cardwell, who couldn’t be evacuated. The complex was threatened by Yasi’s storm surge, which exceeded 3 m (9.8 ft).

Cyclone Yasi – A Category 5 Cyclone -the Largest Cyclone In Queensland’s History

The group was later reported to be safe. Around 10:30 pm standard time on 2 February, Premier Bligh stated that an estimated 90,000 structures, including evacuation centres, were without power. This figure rose to 170,000 by morning, and officials stated that some residents could also be without power for over a month.

The water-supply system had failed in Townsville, & there was only 24 hours supply, while the water had run out at Magnetic Island at some point.

Fears of total devastation to the banana & sugar cane harvest arose because the storm struck land. Initial estimates stated that damage to sugar cane alone could reach A$505 million.

On 3 February, total losses from the storm were estimated to achieve A$3.5 billion (US$3.54 billion). This makes it the most expensive Cyclone ever to hit Australia (not accounting for inflation). By 5 February, A$2 billion (US$2.03 billion) was confirmed to have been destroyed in agriculture, mining, and local government. A further A$1 billion has been lost within the tourism industry.

Thanks to carbon monoxide gas poisoning by the exhaust of a transportable generator used in a very confined space at Bambaroo near Ingham a man lost his life.  This was the only confirmed loss of life as directly attributed to the intense tropical system.

Two days after landfall, severe & catastrophic flooding from the intense rainfall had severed the Bruce Highway between Townsville and Ingham, leaving a ten kilometre backup of traffic. Many of these who evacuated the devastated areas, including emergency workers, were stranded.

On 5 February, Yasi’s remnants as a tropical low created torrential rain as rainfall of 140 mm (5.5 in) was recorded in Terowie & Yongala. Flooding was widespread in communities of northern South Australia, reaching even Renmark on the River Murray. In northwest Victoria, Mildura recorded the best daily rainfall total on record, with 142 mm (5.6 in), and Lyndhurst, a suburb of Melbourne, recorded 180 mm (7.1 in) of rain within the 24 hours falling up to 9 am AEDT (22:00 UTC) on 5 February.

On 6 February, the BOM reported that Ex-Tropical Cyclone Yasi was 85 km (53 mi) north of Yulara which heavy rains continued within the Alice Springs area. The deluge was also sustained in northern South Australia as vast areas continued to get rain. Hallett had its highest recorded rainfall amount of 98 mm (3.9 in). Damaging winds with gusts of over 90 km/h hit Marla and Coober Pedy. Over 100 mm (3.9 in) also fell at Arkaroola, & Mt Dare, 92 mm (3.6 in) fell at Marree, and 86 mm (3.4 in) at Yunta.

Even one week after the flooding rains, areas that were affected had become completely isolated. At Challenger Gold Mine, 150 people were isolated, & emergency supplies had to be flown in. Cattle Stations near Oodnadatta, Glendambo, and, at Anna Creek Station (the world’s largest) were all isolated.

Cyclone Yasi – A Category 5 Cyclone -the Largest Cyclone In Queensland’s History

The Australian Defense Force (ADF) response was designated Operation Yasi Assist. The ADF established Joint Task Force 664, based at Lavarack Barracks in Townsville and under the command of Brigadier Stuart Smith, for operational control on 2 February 2011.

Severe Tropical Cyclone Yasi began forming as a tropical low northwest of Fiji on 29 January and began tracking on a general westward track. The system quickly intensified to a cyclone category to the north of Vanuatu & was named Yasi at 10 pm on the 30th by Fiji Meteorological Service.

Yasi maintained a westward track & rapidly intensified to a Category 2 by 10 am on 31 January, then further to a Category 3 by 4 pm on an equivalent day.

Yasi maintained Category 3 intensity for 24 hours before being upgraded to a Category 4 at 7 pm on 1 February. During this point, Yasi began to take a more west-southwestward movement and started to accelerate towards the tropical North Queensland coast.

Yasi showed signs of further intensification & at 4 am on 2 February and was upgraded to a marginal Category 5 tropical cyclone system. Yasi maintained this intensity & its west-southwest movement, making landfall on the southern tropical coast near Mission Beach between midnight and 1 am early Thursday 3 February.

Being such a robust and enormous system, Yasi maintained a powerful core with damaging winds & heavy rain, tracking westwards across northern Queensland, and eventually weakened to a tropical low near Mount Isa around 10 pm on 3 February.

Yasi is one of the most powerful cyclones to have affected Queensland since records commenced. Previous cyclones of a comparable strength intensity include the 1899 storm Mahina in Princess Charlotte Bay, and also the two cyclones of 1918 at Mackay (January) and Innisfail (March).

Cyclone Wind Damage

There aren’t any verified observations of the highest wind gusts near the cyclone centre at the time of writing. However, a barograph at the Tully Sugar Mill recorded a minimum pressure of 929 hPa because the eye passed over, suggesting wind gusts of about 285 km/h were possible.

This is often supported by measurements (subject to verification) from instrumentation operated by the Queensland Government (Department of Environment & Resource Management) at Clump Point (near Mission Beach), which recorded a minimum pressure of 930hPa. Significant wind damage was reported between Innisfail & Townsville, where the Cyclone’s destructive core crossed the coast. Tully & Cardwell suffered major damage to structures & vegetation with the eye of the Cyclone passing over Dunk Island & Tully around midnight on 2 February.

Cyclone Yasi – A Category 5 Cyclone -the Largest Cyclone In Queensland’s History

The largest rainfall totals were near & to the south of the Cyclone and were generally within the order of 200-300mm within the 24 hours to 9 am Thursday. These rainfall totals were experienced within the area between Cairns and Ayr, causing some flooding. The very best totals were; South Mission Beach 471mm, Hawkins Creek 464mm, Zattas 407mm, Bulgun Creek 373mm along the Tully and Herbert River catchments.

Cyclone Track and Intensity Information for Severe Tropical Cyclone Yasi

Storm Tides

A 5 metre tidal surge was observed at the Department of Environment and Resource Management (DERM) storm tide gauge at Cardwell, which is 2.3 metres above the Highest Astronomical Tide (HAT).

The anomaly occurred at about 1.30 am on a falling tide, averting more severe inundation. Some significant, yet far less substantial sea inundation occurred on the late morning tide on 3 February between the Cairns Northern Beaches & Alva Beach, with peak levels measured at DERM’s Townsville tide gauge near to the expected 0.6m above HAT causing inundation of parts of the town.

Cyclone Yasi – A Category 5 Cyclone -the Largest Cyclone In Queensland’s History

***All information with reference to intensity and track is preliminary information based on operational estimates and subject to vary following post-analysis***
This was the fourth tropical Cyclone within the Queensland area of responsibility during the 2010/11 season.

* All times mentioned in Australia Eastern local time (EST)

Coastal Crossing Details

  • Crossing time:12 am – 1 am EST, 3 February 2011
  • Crossing location: Near Mission Beach, 138km S of Cairns

Extreme Values During The Cyclone Event (estimated)

Note that these values could also be changed on the receipt of later information.

  • Maximum Category:5
  • Maximum sustained wind speed:205 km/hr (estimated)
  • Maximum wind gust:285 km/hr (estimated)
  • Lowest central pressure:929 hPa

Further reading

Weather Maps and Tools


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