OPHELIA

History

Tropical Cyclone Ophelia was a moderate, entirely offshore system that affected waters off north-western Australia in January 1986. Its precursor tropical low was first monitored on 5 January, having developed along a weak monsoon trough in the eastern Indian Ocean to the north of Cape Leveque. Drifting steadily south-westward across warm sea surface temperatures, the low became progressively better organised and was named Ophelia by the Bureau of Meteorology's Tropical Cyclone Warning Centre in Perth on 8 January, when it was situated roughly 250 km north-north-west of Broome as a Category 1 system.

A mid-level ridge of high pressure over the Australian interior steered Ophelia on a south-westward course that kept it running roughly parallel to the Pilbara coastline. The cyclone deepened on 9 January, reaching its peak intensity as a Category 2 system on the Australian scale near 17.5°S, 118.0°E, with an estimated minimum central pressure of about 980 hPa. Maximum 10-minute sustained winds were assessed at approximately 95–105 km/h, with gusts to around 140 km/h. Ophelia maintained this strength for roughly a day as it passed well to the north of Port Hedland and Dampier.

Conditions deteriorated on 11 January when an upper-level trough moved over Western Australia, generating strong westerly vertical wind shear that displaced the deep convection away from the low-level circulation centre. Ophelia weakened rapidly, falling below cyclone intensity and dissipating over open water north of North West Cape on 12 January.

The system never approached the coast closely enough for gale-force winds to reach the mainland, with only localised squalls and increased cloudiness from the outer rainbands affecting the West Kimberley and Pilbara coasts. Marine gale warnings were maintained for shipping lanes and offshore production facilities on the North West Shelf, and some operations near the Dampier and Karratha fields saw minor precautionary delays, but no structural damage occurred. No deaths or injuries were attributed to the cyclone, making Ophelia one of the more benign systems of an otherwise busy 1985–86 season.

Sources: Bureau of Meteorology report Wikipedia