ALAN

History

Severe Tropical Cyclone Alan was a brief but intense system that remained entirely over water during its four-day life in the Arafura and Timor Seas in late January 1976.

Alan originated within an active monsoon trough over the western Arafura Sea on 29 January 1976. Moving west-southwestward across warm tropical waters to the north of Melville Island, the disturbance organised quickly and was classified as a tropical cyclone later the same day, being named Alan by the Bureau of Meteorology's Tropical Cyclone Warning Centre in Darwin.

A ridge of high pressure over central Australia steered the system on a steady west-southwesterly course, running roughly parallel to and offshore from the northern Kimberley coast. Intensification continued through 30 January, when Alan reached severe tropical cyclone status — Category 3 on the Australian scale. Peak intensity was attained over the Timor Sea to the north of Cape Londonderry, with an estimated minimum central pressure near 960 hPa. Maximum sustained winds were of the order of 130–140 km/h (70–75 knots), and gusts over the open ocean were estimated to have exceeded 185 km/h.

The cyclone's strength proved short-lived. As Alan tracked further west into open waters, dry continental air intruded at mid-levels and vertical wind shear increased, stripping away its convection. The core structure broke down on 31 January and the low-level circulation dissipated completely over the ocean on 1 February, with no landfall at any stage.

Because the destructive core stayed well out to sea, mainland impacts were minor. Outer monsoonal rainbands delivered squally showers and isolated gale-force gusts to coastal parts of the Top End and the north Kimberley, including the Darwin area. Gale and storm warnings were issued for shipping across the Arafura and Timor Seas, and vessels diverted without incident. No deaths, injuries or structural damage on land were attributed to Alan.

Sources: Bureau of Meteorology report Wikipedia