Cyclone yasi – a category 5 cyclone -the largest cyclone in queensland’s history

An Introduction To Cyclone Yasi

Cyclone Yasi was the most intense Cyclone and tropical storm to 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.

The severe tropical Cyclone Yasi, a powerful and destructive tropical storm, made landfall in northern Queensland in Australia in early 2011 and caused significant damage to the areas.

January 31st, 2011. The system began as a tropical low close to Fiji on January 26th. It strengthened into a tropical cyclone during the night of January 30th Yasi grew rapidly over the next 24 hours and was rated a Category 3 Cyclone at 5 p.m. AEST (07:00 UTC).

The Cyclone strengthened to a Category 4 system late on February 1st. It then intensified into a Category 5 Severe Tropical Cyclone in early February 2nd.

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.

Cyclone yasi category damage

At about midnight AEST (14:00 UTC) on February 3rd, Yasi passed 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.

The eye passing over Tully caused a record low of 929hPa (27.43inHg), which was recorded. The system’s size and strong core allowed Yasi to maintain cyclonic intensity further inland than anticipated. It eventually dissipated into a tropical low close to Mount Isa at 10 p.m. on February 3rd, 2011, 22 hours after the storm struck the coast.

The storm generated an estimated AU of $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 indirectly contributed to the death of a 23-year-old man who succumbed to exhaust from his generator.

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 Cairns and Townsville and caused only minor damage. The structural damage was estimated at around AU$100 million in early estimates.

Because it missed major cities, it didn’t do as much damage as the government had hoped. However, it did destroy 30% of Tully’s homes.

The destruction of at least 75% of the banana harvest and damage to sugarcane farms was estimated to have cost around AU$ 500 million. One hundred fifty thousand homes were left without electricity after the destruction of power lines.

Cyclone yasi category damage

How Cyclone Yasi was Formed

Fiji Meteorological Service, FMS (Fiji Meteorological Service) initially identified Tropical Disturbance 09F on January 26th, 2011. It had travelled 330 km (205 miles) south-southwest from Tuvalu.

It was expected to grow slowly as it moved southwest, despite high sea surface temperatures and low to moderate wind shear. It did not show any significant development over the next two days. However, it was classified as a Tropical Depression on January 27th.

The tropical depression was characterized as a low-level, poorly-developed low by January 28th. It had a large area of flaring, rotating convection. A lot of development occurred the next day, prompting the Joint Typhoon Warning Center to issue a Tropical Cyclone Formation Alert.

The storm’s low-level rotation centre was more clearly defined. Convective banding characteristics became apparent along the tropical depression’s northern margin.

The storm grew rapidly over January 30th. JTWC upgraded it to a tropical system after data from ASCAT showed winds close to gale force around the storm’s centre. The FMS shortly afterwards classified the storm as Tropical Cyclone Yasi.

Yasi, a tropical storm, was named northeast of Vanuatu at 370 km (230 miles). The storm tracked westward along the northern fringe of a strong subtropical ridge, passing through the country’s north island.

Yasi intensified rapidly and reached severe tropical cyclone intensity on January 31st. For ten minutes, the storm was accompanied by sustained winds of at least 120 km/h (75mph).

Later that day, the Cyclone passed 160degE. This prompted the FMS to issue the final advisory and the Australian Bureau of Meteorology to issue the first advisory.

(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.

The Solomon Islands, Vanuatu, and parts of Australia were directly affected by Severe Tropical Cyclone Yasi. Fiji and Papua New Guinea, however, were indirectly affected. The system’s collisions caused the name Yasi to be withdrawn from the South Pacific tropical cyclone record and replaced by Yvonne.

Cyclone yasi category damage

Fiji, Vanuatu and Papua New Guinea, as well as the Solomon Islands Impacts

From 23-30 January, strong winds and large swells were observed in Tuvalu during Tropical Cyclones Wilma’s (or Yasi) formation and crossing. Students studying in Fiji and Vaitupu were affected by these powerful winds, which also limited shipping schedules.

The rough seas also made it difficult for the outer islands to get fresh supplies. Between 28 and 30 January, Yasi’s tropical depression precursor produced strong winds and rain over the Fijian Islands of Rotuma, Vanua Levu and Taveuni and, therefore, the northern Yasawa Islands.

With 95 km/h (60mph) winds, Tropical Cyclone Yasi swept over Vanuatu’s northern Torba Province. Yasi was the second of three systems to directly impact Vanuatu on January 30th. Officials from Vanuatu reported difficulty in reaching the Torba Province. However, it was believed that significant damage to the northern region had been avoided.

Cyclone yasi – a category 5 cyclone -the largest cyclone in queensland’s history
Cyclone yasi track map 2011

Although the storm was several hundred kilometres southwest of Papua New Guinea’s coast, the system’s outer edges produced solid gales and high seas that brought heavy rain to the country. Milne Bay Province officials advised residents to move to higher ground if they lived along the coast.

Cyclone Yasi Hits Willis Island

Yasi crossed into the Australian region. The meteorological data from Willis Island’s meteorological observation station was used to observe the system. Staff evacuated the island on February 1st by helicopter after they had batted down the buildings. Yasi then passed directly over the meteorological observatory on February 2nd.

Before the meteorological equipment and connections failed, wind gusts of 185 km/h (115 MPH) and a minimum pressure of 937.9 hPa (27.70 InHg) were recorded. It was clear that strong winds and storm surges had caused damage to the radar and critical observing systems and 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.

After Cyclone Yasi passed over the island, most automated surface observing systems and communications were restored and operational.

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 in December 2011.

Cyclone yasi category damage

Australian Impacts

Preparations for the storm had already begun by the time Yasi reached the Australian basin. Media outlets described the storm as “what may be the state’s most severe cyclone in recent 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.

Anna Bligh, the Queensland Premier, urged thousands of residents to move out of the storm’s path. Thirty thousand people were evacuated from Cairns. This included all Cairns Base Hospital patients and Cairns Private Hospital patients.

They were airlifted by the Royal Australian Air Force and other agencies (such because of the Royal Flying Doctor Service – RFDS) to Brisbane. The Queensland state emergency coordinator advised residents that they could be left alone for up to 24 hours if it was too dangerous for emergency personnel.

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.

Wind gusts of up to 290 km/h (180 MPH) were recorded at Mission Beach, close to where Cyclone Yasi hit, causing extensive damage.

The storm surge was estimated to have reached 7m (23ft) in height, swept up several structures on the coast and pushed 300m (980ft) inland towards the interior. Police couldn’t leave their station grounds within hours of the storm’s passing because it was still not declared safe.

Cyclone yasi category damage

The exposed beaches had lost most of their sand, and every structure was damaged. Mission Beach was not affected by the storm’s eye at sunrise on February 3rd.

News reporters made brief damage assessments as the storm’s eye passed over many Queensland towns before it returned. The worst-affected areas were Tully, Silkwood and Tully Heads, Mission Beach (Innisfail), and Cardwell.

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

An unknown number of houses were destroyed by intense winds that whipped the area at speeds of 209 km/h (130 MPH). Other dwellings were not damaged by severe roof and facade damage. According to reports, about 90% of structures along the main avenue suffered severe damage as dawn broke.

Innisfail’s evacuation point began to flood as the worst effects of Yasi’s impact neared. To stop water from entering further, evacuees were reportedly tapping boards at the doors’ base. Concerns were raised about the windows of the building as they were flexed in winds exceeding 200 km/h (120 MPH).

In Townsville, numerous roofs were torn off buildings & sent hurtling down the streets. Residents reported hearing the glass crackling throughout the night as the storm passed. The high school in Tully was destroyed, but it was rebuilt.

Residents trapped near the storm’s peak made numerous emergency calls. However, their calls couldn’t be acted upon as conditions were too dangerous for police to travel. Six people were trapped in an apartment building at Port Hinchinbrook, near Cardwell. They couldn’t be evacuated. Yasi’s storm wave, which reached 3 m (9.8 feet) high, threatened the complex.

Later, the group was reported to have been safe. Premier Bligh said that 90,000 structures, including evacuation centres, were without power at 10:30 p.m. on February 2nd. The number jumped to 170,000 in the morning. Officials also stated that some residents might be without power for more than a month.

Cyclone yasi category damage

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.

The storm-battered land caused fears of destruction to the sugarcane and banana harvests. Initial estimates indicated that the damage to sugarcane could exceed A$505 million.

The storm’s total losses were estimated at A$3.54 billion (US$3.54 trillion) on February 3rd. This Cyclone is the most costly to hit Australia if inflation is not considered. A$ 2 billion (US$ 2.03 billion) had been lost in mining, agriculture and local government by February 5th. A further A$ 1 billion has been lost in the tourism sector.

A man died from carbon monoxide poisoning caused by the exhaust of a portable generator used in very restricted spaces at Bambaroo, near Ingham. This was the only death directly attributable to the intense tropical storm.

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

On February 5th, Yasi’s remnants, a tropical low, created torrential rain in Terowie and Yongala. This resulted in the area’s rainfall of 140mm (5.5 inches). Flooding was widespread across northern South Australia.

It reached Renmark on the River Murray. Mildura in northwest Victoria had the highest daily rainfall total, at 142mm (5.6 inches). Lyndhurst, a suburb in Melbourne, saw 180mm (7.1 inches) of rain in the 24 hours ending at 9 a.m. AEDT (22:00 UTC) on February 5th.

Cyclone yasi category damage

On February 6th, the BOM reported that Ex-Tropical Cyclone Yasi had passed 85km (53 miles) north of Yulara. Heavy rains continued in the Alice Springs region. As the rain continued to fall in large areas of northern South Australia, the deluge also continued. Hallett recorded a record-breaking 98mm (3.9 in) of rainfall.

Marla and Coober Pedy were hit by powerful winds of more than 90 km/h. Arkaroola and Mt Dare also suffered heavy losses. Marree was hit with 92 mm (3.76 in), while Yunta received 86 mm (3.41 in).

Even one week later, the floods had caused areas to become isolated. One hundred fifty people were evacuated from Challenger Gold Mine. Emergency supplies had to be flown in. Cattle Stations near Oodnadatta, Glendambo, and Anna Creek Station (the worlds largest) were all isolated.

Cyclone yasi category damage

Operation Yasi Assist was the Australian Defense Force’s (ADF) response. 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 February 2nd 2011.

On January 29th, Severe Tropical Cyclone Yasi formed as a tropical low in northwest Fiji and tracked on a generally westward path. Fiji Meteorological Service named Yasi on the 30th at 10 p.m.

Yasi kept a westward track and quickly intensified to a category two by 10 a.m. on January 31st. Then further to category three by 4 p.m. on the same day.

Yasi maintained Category 3 intensity for 24hrs before being upgraded from Category 4 at 7 p.m. on February 1st. Yasi started to move more to the west and southward towards the tropical North Queensland coast.

Yasi was showing signs of intensification. At 4 a.m. on February 2nd, Yasi was upgraded to a marginal Category 5-tropical cyclone system. Yasi continued to intensify its west-southwest motion, making landfall near Mission Beach on the southern tropical coast between midnight and early Thursday morning, February 3rd.

Cyclone yasi category damage
Cyclone yasi satellite image

Yasi was such an enormous and robust system that it maintained a strong core with destructive winds & heavy rainfall, tracking westwards through northern Queensland. It eventually weakened to a tropical low close to Mount Isa at 10 p.m. on February 3rd.

Yasi is the strongest Cyclone to hit Queensland since records began. Similar strength cyclones have been experienced, including the 1899 storm Mahina at Princess Charlotte Bay and the two cyclones 1918 at Mackay (January and March).

Cyclone Wind Damage

At the time of writing, there are no verified observations of wind gusts at their highest near the cyclone centre. A barograph at Tully Sugar Mill measured a minimum pressure reading of 929 hPa as the eye passed above, suggesting that wind gusts up to 285 km/h are possible.

Cyclone yasi category damage

Instrumentation at Clump Point (near Mission Beach) by the Queensland Government (Department of Environment & Resource Management) is often verified. It recorded a minimum pressure of 930hPa.

Innisfail and Townsville were the most affected by the Cyclone’s destructive centre. Tully & Cardwell sustained significant damage to structures & vegetation when the eye of the Cyclone passed over Dunk Island & Tully at midnight on February 2nd.

The Cyclone’s closest and most significant areas received the greatest rainfall. They averaged 200-300mm in the hours from 9 a.m. Thursday. These rainfall totals were experienced within the area between Cairns and Ayr, causing some flooding.

These were South Mission Beach’s 471mm, Hawkins Creek’s 464mm and Zattas’s 407mm. Bulgun Creek was 373mm and Bulgun Creek 373mm. They also reached the Tully-Hunter River catchments.

Cyclone yasi category damage

Track and Intensity Information For Severe Tropical Cyclone Yasi

Storm Tide

At Cardwell’s Department of Environment and Resource Management storm tide gauge, a 5-metre tidal surge could be seen. This is approximately 2.3 metres above Highest Astronomical Tide (HAT).

A significant but not as severe sea inundation occurred between the Cairns Northern Beaches & Alva Beach on February 3rd. A falling tide caused this anomaly at 1.30 a.m. It prevented more severe flooding. Peak levels were measured at the DERM Townsville tide gauge and were close to the expected 0.6m above the HAT, causing flooding in parts of the town.

***All information concerning intensity and track is a preliminary report 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.

Cyclone yasi category damage

* 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 upon receiving later information.

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

Further reading

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