ALISTAIR

History

Tropical Cyclone Alistair formed late in the 2000–01 season, developing from a weak tropical low embedded in an active monsoon trough over the Timor Sea, north of Darwin, on 17 April 2001. Warm sea surface temperatures allowed the system to organise quickly as it tracked towards the west-southwest, and it was upgraded to a Category 1 cyclone late on 17 April, with the Darwin Tropical Cyclone Warning Centre assigning the name Alistair. Further consolidation followed, and the system reached Category 2 strength on the Australian scale on 18 April.

Between 19 and 21 April, Alistair held a steady west-southwesterly course that ran roughly parallel to the Kimberley coastline, fluctuating between Category 1 and Category 2 intensity as it skirted the far north-west of Western Australia. Its closest approaches to land came near Troughton Island and Cape Leveque. At peak intensity the cyclone's central pressure fell to about 980 hPa, with maximum ten-minute mean winds near 100 km/h and gusts estimated at up to 140 km/h.

As the system continued southwest towards the Pilbara coast in the vicinity of Onslow and Carnarvon, conditions turned hostile. Strong mid- to upper-level westerly shear combined with dry air intruding at mid-levels to displace the thunderstorm activity from the low-level circulation. Alistair weakened swiftly, falling below cyclone intensity and becoming a tropical low on 22 April. The remnant circulation drifted over open water before dissipating on 24 April, meaning the cyclone never crossed the coast.

Impacts were consequently light. Troughton Island experienced gale-force winds and squally rain as the core passed nearby, while west Kimberley coastal communities saw raised tides and patchy rainfall, but no structural damage was reported anywhere on land. In the offshore oil and gas sector on the North West Shelf, non-essential staff were withdrawn and production was briefly suspended as a precaution, though the storm's rapid decline prevented any significant disruption. No deaths or injuries were attributed to Alistair.

Sources: Bureau of Meteorology report Wikipedia