Severe Tropical Cyclone Laurence

13-23 December 2009


A tropical low formed in the monsoon trough in the Arafura Sea on 8 December and moved west. On 12 December the system passed very close to Darwin and although it had not reached tropical cyclone strength, it produced a brief period of gales, heavy rainfall and some minor tree damage in Darwin suburbs. The low continued to track west, moving into the Joseph Bonaparte Gulf during 13 December and reached tropical cyclone strength by 0800 WST 14 December. As Laurence intensified rapidly into a small but intense system, it passed over Troughton Island which recorded a wind gust to 187 km/h (101 kn) and a lowest pressure of 982 hPa. The cyclone moved in a south westerly direction, parallel to the Kimberley coast. Despite its proximity to the coast the system reached category 5 strength with a very small radius to gales of 40 km (20 nm) and radius to maximum wind (RMW) of 10 km (5 nm). It eventually crossed the Kimberley coast at Collier Bay, east of Koolan Island on 16 December.

As Laurence moved inland the system produced some heavy rainfall even as it rapidly weakened. The remains of the system moved initially south, and then west. A well defined circulation was maintained and once the system moved off the Dampier Peninsular (Kimberley coast) at 0800 WST 19 December it quickly reformed into a tropical cyclone. The system moved initially south west and then turned south southeast while intensifying rapidly. During this period Laurence had a radius to gales of approximately 90-110 km (50-60 nm) - much closer to the climatological average - and a radius to maximum winds of 15-20 km (8-10 nm). Laurence again reached category 5 strength at 1400 WST 21 December, just prior to crossing the coast around 1700 WST near Wallal, along the 80 Mile Beach, 230 km north east of Port Hedland. There was considerable damage to properties in the area and an estimated 1500 cattle perished. Mandora recorded a wind gust to 211 km/h (114 kn) and a lowest pressure of 929 hPa. Once Laurence moved inland the system steadily weakened and was below cyclone strength by 2000 WST 22 December. Heavy rain fell in the eastern parts of the De Grey river catchment causing minor flooding, road closures but no major damage to infrastructure.

For more details see the TC Laurence Report (pdf)

Track and intensity

Best Track of Tropical Cyclone Laurence