SAM

History

Severe Tropical Cyclone Sam developed from a weak tropical low near Darwin on 12 January 1990, forming within the active monsoon trough that characterised the above-average 1989–90 Australian cyclone season. The system moved westward into the Timor Sea, reaching tropical cyclone intensity on 13 January before tracking on a west-southwesterly to southwesterly course that kept it well offshore and roughly parallel to the Western Australian coastline.

As Sam moved into the open Indian Ocean, it steadily intensified. On 18 January, satellite imagery revealed a weakly defined eye at the storm's centre, and the system reached its peak that night as a Category 3 severe tropical cyclone on the Australian scale, with an estimated minimum central pressure of 966 hPa. Shortly afterwards, increasing vertical wind shear and cooler waters to the south caused rapid weakening, and Sam fell below cyclone intensity by 20 January.

A notable meteorological feature of Sam's lifespan was its interaction with the smaller and weaker Tropical Cyclone Rosita, which had formed to Sam's west. Sam's broad circulation dominated the surrounding environment, trapping Rosita and forcing it to orbit the larger storm's periphery before it was sheared apart and absorbed. Because Sam remained entirely over open ocean throughout its existence, it produced no structural damage or coastal impacts on the Australian mainland, and no casualties were recorded.

Sources: Bureau of Meteorology report Wikipedia