BONNIE

History

Tropical Cyclone Bonnie was a late-season system of the 2001–02 Australian region season, and one whose greatest impact came before it was even named. The storm's origins lay in a tropical low that developed over the Banda Sea around 9 April 2002. Drifting south-southwestward, the disturbance passed directly over Timor Island on 10–11 April. Although surface winds remained modest at that stage, the low carried extremely heavy rainfall, and it was this phase of its life that proved deadly.

Emerging over the warm waters of the Timor Sea to the west of Darwin, the system consolidated quickly in a favourable environment. It reached Category 1 strength on 11 April and was named Bonnie by the Bureau of Meteorology's Darwin Tropical Cyclone Warning Centre. Continuing on a west-southwesterly path roughly parallel to the northern Western Australian coastline, Bonnie strengthened further and attained Category 2 intensity on 12 April. At its peak the cyclone had an estimated minimum central pressure near 980 hPa, with maximum ten-minute sustained winds of about 100 km/h and gusts to around 140 km/h.

The peak was short-lived. Strong upper-level wind shear began to affect the cyclone late on 12 April, displacing the deep convection away from the low-level centre. Bonnie weakened rapidly, falling below cyclone intensity on 13 April, and the remnant low dissipated over open water north of the Kimberley coast on 14 April. The system never made landfall as a cyclone.

The heaviest consequences were felt on Timor, where torrential rain from the precursor low triggered flash flooding and landslides across both East Timor and Indonesian West Timor. At least 19 people were killed, and housing, roads and agricultural land sustained considerable damage. In Australia, Bonnie stayed far enough offshore to spare the Top End and Kimberley coasts; gale-force winds and heavy swells were experienced at Ashmore Reef as the centre passed nearby, but no Australian casualties or significant structural damage were reported.

Sources: Bureau of Meteorology report Wikipedia