Meteorological Info

Cyclone Tracy was a tropical cyclone that was formed on the 21st of December but devastated the city of Darwin from Christmas day to the 26th of December, 1974. It is the most compact cyclone or equivalent strength hurricane to ever hit Australia on record, with gale force winds extending only 48 kilometres from the centre, in fact, it was the most compact cyclone in the world until tropical storm Marco, of the 2008 Atlantic hurricane season broke the record, with winds extending only 19 kilometres from the centre.

After Cyclone Tracy formed of the Arafura Sea, it moved southwards and affected Darwin with category four winds on the Australian Cyclone Intensity Scale.

After a lot of working out, Cyclone Tracy killed 71 people, caused eight hundred and thirty seven million dollars of damage, destroyed more than 70% of Darwin’s buildings and destroyed 80% of the houses . It left more than 41,000 of the 47,000 inhabitants of the city homeless prior to landfall and required the evacuation of over 30,000 people. Most of the people evacuated were sent to Adelaide, Alice Springs or Sydney and many never returned. Meteorological info

On the 20th of December 1974, the United States ESSA-8 environmental satellite recorded a large mass of clouds centred in the Arafura Sea about 370 kilometres northeast of Darwin. This distance was tracked by the Darwin weather bureaus regional director, Ray Walkie and by senior meteorologist Geoff Crane.

On the 21st of December 1974, the ESSA-8 satellite showed evidence of a newly formed circular centre near latitude 8 south and longitude 135 east. The meteorological duty officer at the time, Geoff Crane, issued the initial tropical cyclone alert describing the storm as a tropical low that could develop into a tropical cyclone. Later in the evening, the Darwin meteorological office received an infrared satellite image from the national oceanic and atmospheric administration’s satellite, NOAA-4, showing that the low pressure had developed further and that the spiralling clouds could be observed.

The storm was officially pronounced as a tropical cyclone at around 10P.M. on the 21st of December, when it was around 200 kilometres to the northeast of Cape Don.

Cyclone Tracy was first observed on the morning of the 22nd of December. Over the next few days, the cyclone moved in a south-easterly direction, passing the north of Darwin. That day there was a broadcast on ABC radio that stated, Cyclone Tracy poses no immediate threat to Darwin, however, in the morning of the 24th of December, Cyclone Tracy rounded Cape Don on the Western tip of Bathurst Island and moved in a south-easterly direction, straight towards Darwin. The bureaus weather station at Cape Fourcoy measured a wind speed of 120 kilometres an hour at 9A.M. that morning.

By late afternoon on the 24th of December, the sky over the city was heavily overcast, with low clouds, and was experiencing strong rain. Wind gusts increased the strength between 10P.M. and midnight, the damage became serious and residents began to realise that the cyclone would not pass by the city, but over it.

On the 25th of December at around 3:30 A.M., Cyclone Tracy’s centre crossed the coast near Fannie Bay. The highest wind gust from the cyclone was 217 kilometres per hour, which was recorded around 3:05 A.M. at Darwin Airport. The anemometer failed at around 3:10 A.M., with the wind vane destroyed after the cyclones eye. The bureau of meteorology’s official statement estimates suggested that Cyclone Tracy’s gusts had reached 240 kilometres. The lowest air pressure reading during Cyclone Tracy was 950 hectopascals, which was taken at around 4 A.M., by a bureau staff member at Darwin Airport. This was recorded in the eye of the cyclone.

From around 6:30 A.M., the winds began to ease, with the rainfall ceasing at around 8:30 A.M. Preparations

Darwin had been severely hit by cyclone before, in January 1897 and again in March 1937. However, in the 20 years leading up to cyclone Tracy, the city had had a period of rapid expansion. Though building standards required that some attention be given to the possibility of cyclones, most buildings were not capable of withstanding the force of a cyclones direct hit.

On the day of the cyclone, most residents of Darwin believed that it would not cause any damage to the city. Cyclone Selma had been predicted to hit Darwin earlier that month, but it instead went north and dissipated with effecting Darwin in any way. As a result, Cyclone Tracy took most residents by surprise. Despite several warnings, the people of Darwin did not evacuate or prepare for the cyclone, many people continued to prepare for Christmas and many attended Christmas parties, despite the increasing winds and heavy rain.

Aftermath and recovery

In February 1975, Prime Minister, Gough Whitlam, announced the creation of the Darwin Reconstruction Commission, which was given the task of rebuilding the city within five years. The commission was headed by Tony Powell. The damage to the city was so severe that some thought about moving the entire city. However, the government insisted that it be rebuilt in the same location. By May 1975, Darwin’s population recovered, with 30,000 people residing the city. Temporary housing, caravans, hotels and an ocean liner were used to house people, as reconstruction of permanent housing had not started until September that year.

By the following April, and after receiving complaints about the slow speed of construction, the commission had built 3000 new homes in the nearly completely destroyed northern suburbs, and completed repairs for those houses that survived the storm. Several new building codes were drawn up, trying to achieve the competing goals of the quick recovery of the area and ensuring that there would be no repeat of the damage that Darwin took in 1974. By 1978, much of the city had recovered and was able to house almost the same number of people as before Cyclone Tracy had struck. But as much as 60% of Darwin’s population in 1974 was no longer living in the city in the 1980s. In the year that followed, Darwin was almost entirely rebuilt and now shows little resemblance to the Darwin of December1974.