By world standards, Tracy was a small but intense tropical cyclone at landfall, the radius of gale force winds being only about 50 km.
The central pressure of 950 hPa was close to the average for such systems, but the winds were unusually strong. The anemometer at Darwin Airport recorded a gust of 217 km/h before the instrument was destroyed.
Tracy was first detected as a depression in the Arafura Sea on 20 December 1974. It moved slowly southwest and intensified, passing close to Bathurst Island on the 23rd and 24th. Then it turned sharply east-southeastward, and headed straight at Darwin, striking the city early on Christmas Day. Warnings were issued, but - perhaps because it was Christmas eve, and perhaps because no severe cyclone had affected Darwin in many years - many residents were caught unprepared. But even had there been perfect compliance, the combination of extremely powerful winds, and the loose design of many buildings at that time, was such that wholesale destruction was probably inevitable anyway. Forty-nine people were killed in the city and a further 16 perished at sea. The entire fabric of life in Darwin was catastrophically disrupted, with the majority of buildings being totally destroyed or badly damaged, and very few escaping unscathed. The total damage bill ran into hundreds of millions of dollars.
It is hard for anyone who was not there at the time to imagine how it must have felt, however the Museum & Art Gallery of the Northern Territory has a permanent exhibit which is so realistic it's a bit frightening.
When you see whole suburbs without a house standing, the magnitude of this disaster hits home.
Wind speeds of 217 km/h registered at Darwin Airport before the equipment was itself blown away and there are estimates of maximum speeds of up to 300 km/h.
Seeing this destruction also brings home another matter - Darwin is a very new city simply because there was almost nothing left standing when Tracy had finished her work.
Before the storm Darwin was a “big town” of 45,000 where isolation from the rest of Australia was both a curse and a boon. As Greta Quong remembers, it made for lousy shopping. But she and her husband Eddie also recall an easygoing town where everyone knew everyone else. It was also a place where many were blissfully unaware of their vulnerability to a tropical cyclone. When cyclone Selma narrowly missed early in December 1974, it prompted a local architect Peter Dermoudy to warn many houses would not stand up to a big wind. While the authorities advised staying at home was the best option in a cyclone, he reckoned the safest place was out of town away from buildings and out of the path of flying debris.
In the week leading up to Christmas another cyclone formed in the Arafura Sea and began to track southwest behind the Tiwi Islands. Most folk thought it would go the way of Selma; out of sight, out of mind. But on the morning of Christmas Eve it changed direction and headed straight for Darwin. A former Darwin weatherman, Geoff Crane (now second in command with the Queensland Met Bureau) recalls how the first warning for Darwin went out during the ABC Country Hour shortly after midday.
Cyclone Tracy was a tropical cyclone that devastated the city of Darwin, Northern Territory, Australia, from Christmas Eve to Christmas Day, 1974. It is the most compact hurricane or equivalent-strength tropical cyclone on record in the Australian basin, with gale-force winds extending only 48 kilometres (30 mi) from the centre and was the most compact system worldwide until 2008 when Tropical Storm Marco of the 2008 Atlantic hurricane season broke the record, with gale-force winds extending only 19 kilometres (12 mi) from the centre. After forming over the Arafura Sea, the storm moved southwards and affected the city with Category 4 winds on the Australian cyclone intensity scale, while there is evidence to suggest that it had reached Category 3 on the Saffir-Simpson Hurricane Scale when it made landfall.