The system was subsequently named Amos during April 20, after it had developed into a tropical cyclone and started to move north-westwards towards the island nation of Tuvalu.

Tropical Disturbance 17F was first noted by the Fiji Meteorological Service on April 13, while it was located about 130 km (80 mi) to the northwest of the Fijian dependency of Rotuma.

[2][3] The system was subsequently classified as a tropical depression on April 16, as passed near or over several islands in Fiji's Northern Division including Vanua Levu.

[3][6] A tropical cyclone formation alert on the system was issued by the United States Joint Typhoon Warning Center during that day, as the well defined low level circulation centre consolidated.

[13][14] Amos subsequently peaked as a Category 3 Severe Tropical Cyclone, with ten-minute sustained wind speeds of 150 km/h (93 mph) during April 22.

[15] During that day as the cyclone passed within 120 km (75 mi) of Wallis Island, the JTWC estimated that Amos had peaked with 1-minute sustained winds of 165 km/h (103 mph).

[16][17] Over the next day, the system remained at its peak intensity as it accelerated south-eastwards towards the Samoan Islands, where it was expected to pass over either Upolu or Tutuila.

[4][24] As the system impacting the island nation, the Fiji Meteorological Service issued strong wind and heavy rain warnings, for the whole of the archipelago including Rotuma.

[23] Since Amos was forecast to hit Samoa as a Category 4 storm on April 24, emergency preparations went underway with water and generators being distributed.