The precursor tropical depression to Cyclone Tusi developed on January 13, within a trough of low pressure near the island nation of Tuvalu.

Tusi's eye subsequently passed near or over American Samoa's Manu'a Islands early the next day, as the system peaked in intensity with 10-minute sustained wind speeds of 150 km/h (90 mph).

During the middle of January 1987, a trough of low pressure was located over the South Pacific Ocean, between Tuvalu and the Southern Cook Islands.

[1] During that day Tusi started to move southwards as it intensified further and developed an eye, before it became a category 3 severe tropical cyclone with hurricane-force winds.

[1][2] Tusi's eye subsequently passed near or over American Samoa's Manu'a Islands early the next day, as the system peaked in intensity with the FMS estimating 10-minute sustained wind speeds of 150 km/h (90 mph).

[1][3] An area of high pressure to the southeast of the system subsequently steered Tusi's remnants westwards, before they were last noted to the northeast of New Zealand on January 25.

As the initial tropical cyclone developed, westerly winds were responsible for some coastal erosion at several places on the Tuvaluan island of Funafuti.

[10][12] The system hurled furniture and appliances through walls and flattened plantations that grew various crops including bananas, oranges, taro and breadfruit.

[12] Ronald Reagan signed a Major Disaster Declaration for American Samoa during January 24, which authorized the use of federal funds in relief and recovery efforts.