 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.Over the next couple of days 17F moved north-eastwards towards the Samoan Islands and passed about to the west of Tonga's Niuas island group during April 18.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.