WALTER

History

Tropical Cyclone Walter began as a tropical low within the monsoon trough over the far eastern Indian Ocean, first identified near 14.6°S, 94.0°E on 3 March 1990 — well to the west of the Western Australian coast and south-southwest of the Cocos (Keeling) Islands. The system organised quickly and was named Walter by the Bureau of Meteorology's Perth Tropical Cyclone Warning Centre on 4 March, when it reached Category 1 on the Australian scale.

Its track proved unusually convoluted. Initially the young cyclone was steered southeast ahead of a high-latitude cold front, but once a ridge of high pressure built in behind the front, Walter swung around to the southwest. It reached an initial peak on 6 March with a minimum central pressure of about 985 hPa, corresponding to Category 2 intensity with 10-minute sustained winds near 95 km/h and gusts to roughly 130 km/h.

Continuing westward into a hostile environment, Walter lost organisation and fell back to tropical low status by 8 March. With steering currents collapsing, the weak remaining circulation wandered erratically, drifting north-northeast before looping back toward the northwest while retaining a shallow low-level centre. Warm open water then allowed the system to rebuild: gale-force winds returned on 12 March and Walter regained Category 1–2 status as it tracked west-northwest. On 13 March it crossed 90°E, leaving the Australian region, and was renamed Gregoara by the Mauritius Meteorological Service, subsequently deepening into a severe system over the open South-West Indian Ocean.

Because Walter formed and remained over remote ocean — staying more than 1,500 km west of the Western Australian coastline and never approaching the Cocos Islands — it produced no landfall and no impacts on any inhabited area. There were no casualties, injuries or structural damage. The only operational consequence was the issuing of high-seas gale and storm warnings for commercial shipping using the eastern and central Indian Ocean routes.

Walter was one of a number of systems that made the 1989–90 Australian region season an above-average one.

Sources: Bureau of Meteorology report Wikipedia