Tropical Storm Melissa is set to intensify into a hurricane on Saturday morning as it moves closer to Jamaica.

According to the Meteorological Service of Jamaica in its latest bulletin, at 4:00 am, the centre of Tropical Storm Melissa was located about 385 kilometres (240 miles) southwest of Port-au-Prince, Haiti, and about 220 kilometres (137 miles) southeast of Morant Point, and 270 kilometres (165 miles) southeast of Kingston, Jamaica.

A hurricane warning remains in effect for Jamaica.

The met office said Tropical Storm Melissa is moving toward the northwest near 6 km/h (3 mph) and a slow west-northwestward to westward motion is expected Saturday through Sunday night. A turn to the north and northeast is forecast on Monday and Tuesday.

Maximum sustained winds are near 110 kilometres (70 mph), with higher gusts. Rapid intensification is expected to begin soon and Melissa is forecast to become a major hurricane by Sunday. Tropical storm force winds extend outward up to 185 kilometres (115 miles) from the centre.

On the forecast track, the centre of Melissa is expected to move from south to north over central Jamaica early next week and over eastern Cuba by the middle of the week.

Tropical Storm Melissa is expected to produce rainfall amounts reaching 350 to 650 mm (15 to 25 inches) over parts of Jamaica in the next few days. Catastrophic flash floods and landslides are likely.

As the tropical storm moves closer to the island, expect tropical storm force to initially affect the island, mainly over eastern parishes by Saturday night, with hurricane conditions expected by Sunday or Monday, the Met Service said.

Small craft operators, including fishers on the cays and banks, are strongly advised to remain in safe harbour until all warning messages have been lifted and wind and sea conditions have returned to normal.

The Meteorological Service said it continues to closely monitor the progress of Tropical Storm Melissa, and all interests are encouraged to pay special attention to further releases.