BESSI

History

Tropical Cyclone Bessi was a weak, poorly organised system that developed late in the 1989–90 Australian region cyclone season over the eastern Indian Ocean. Forecasters first identified the precursor tropical low within a broad monsoon trough on 11–12 April 1990, several hundred kilometres northwest of the Kimberley coast of Western Australia. The low drifted slowly towards the south-southwest across warm water, but persistent vertical wind shear hampered the consolidation of a well-defined inner core, and development was gradual over the following days.

The Bureau of Meteorology's Tropical Cyclone Warning Centre in Perth named the system Bessi on 15 April, when it was assessed as a Category 1 cyclone on the Australian scale. Peak intensity was reached around 15–16 April, with an estimated minimum central pressure near 990 hPa and maximum 10-minute sustained winds of about 75 km/h, with localised gusts to roughly 100 km/h. Even at its strongest, Bessi remained a marginal cyclone: satellite imagery showed no persistent convective banding curling into the centre, and the gale-force winds lay well out in the outer quadrants rather than being tightly wrapped around the low-level circulation.

Bessi continued on a southwestward course into higher latitudes, where increasingly strong upper-level westerly shear displaced and then stripped away what convection remained. The system fell below tropical cyclone strength late on 17 April and dissipated the following day over open water west of Shark Bay.

Because Bessi tracked well out to sea — remaining more than 600 kilometres offshore throughout its life — it had no effect on mainland Australia. High-seas warnings were issued for commercial shipping across the eastern Indian Ocean, but North West Shelf oil and gas installations reported no operational disruption or adverse weather. No deaths, injuries or structural damage were attributed to the cyclone.

Bessi was among the final systems of an above-average season in the Australian region, and one of the least consequential.

Sources: Bureau of Meteorology report Wikipedia