Tropical Cyclone Fina is currently a category one cyclone and is slowly moving south towards the Northern Territory's Top End.

The Bureau of Meteorology (BOM) has issued a cyclone watch alert for communities in north-west Arnhem Land and the Tiwi Islands, with the cyclone likely to increase in strength before making landfall.

It is expected to make landfall on the Tiwi Islands about 1am CST on Saturday morning as a category two system.

The BOM's latest update shows the cyclone has sustained winds of 75 kilometres per hour near its centre, with wind gusts up to 100km/h.

On Sunday and early next week, the system might continue on a south-west path through the Timor Sea, the BOM said.

Live 120-hour Cyclone Fina forecast map

This map shows a 120-hour forecast for Tropical Cyclone Fina'

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