PENNY

History

Severe Tropical Cyclone Penny developed from an active monsoonal low over the Timor Sea, north of the Kimberley region, on 6 November 1974. Favoured by warm sea surface temperatures, the disturbance organised steadily as it drifted west-southwestward, and was classified as a tropical cyclone on 7 November when it lay roughly 300 kilometres north-northwest of Broome. It was named Penny by the Bureau of Meteorology's Tropical Cyclone Warning Centre in Perth on that date.

A strong ridge of high pressure across the Australian continent steered the system along a persistent west-southwesterly course, keeping it well offshore of the Kimberley and Pilbara coastlines throughout its life. Penny intensified over open water, reaching severe tropical cyclone status — Category 3 on the Australian scale — on 10 November. At its peak, positioned to the northwest of North West Cape, the cyclone's central pressure fell to approximately 960 hPa, with maximum 10-minute sustained winds estimated near 130–140 km/h and gusts over the open ocean exceeding 185 km/h.

From 13 November, Penny continued generally westward into the central Indian Ocean, where cooler waters and strengthening vertical wind shear began to erode its structure. The system weakened below tropical cyclone intensity on 14 November and dissipated over open water by 16 November. At no stage did Penny approach or cross the coast.

Because the cyclone remained well out to sea, there were no impacts on mainland Australia — no gale-force winds, flooding rainfall or damage were recorded at Western Australian coastal communities, and no casualties or injuries were attributed to the system. The principal effects were maritime. Storm warnings were maintained for shipping across the North West Shelf, commercial vessels altered their routes to avoid the cyclone's path, and offshore oil exploration platforms implemented heavy weather precautions, though none reported structural damage.

Penny was an early-season system in the 1974–75 Australian region cyclone season, which would later produce the catastrophic Cyclone Tracy at Darwin in December.

Sources: Bureau of Meteorology report Wikipedia