What caused Cyclone Tracy?

Cyclone Tracy resulted from a tropical low in the Arafura Sea between New Guinea and Australia, growing quickly into a tropical cyclone in less than 48 hours. When the slow-moving storm reached the warm waters of the Timor Sea, it became more intense and made landfall as a Category 4 cyclone on December 24, 1974, with top wind speeds of 135 miles per hour recorded in the Darwin, Australia airport before the winds ripped off the location's anemometer.

Cyclone Tracy killed 71 people and injured another 650 while displacing 41,000. It destroyed 80 percent of the buildings in Darwin. The total cost of the storm was projected at $586 million.