A Tropical Storm Watch remains in effect for Jamaica as Melissa slows down over the Caribbean Sea south of Hispaniola.

This means tropical storm conditions pose a possible threat to Jamaica within 48 hours.

The Met Office says as at 4:00 a.m., the centre of tropical storm Melissa was located by an Air Force Reserve Hurricane Hunter Aircraft about 306 miles southeast of Morant Point, Jamaica.

Tropical Storm Melissa is moving toward the west-northwest near 11 kilometres per hour.

A decrease in forward speed and a gradual turn to the northwest and north-northwest is expected during the next few days.

Maximum sustained winds are near 85 kilometres per hour with higher gusts.

Some gradual strengthening is anticipated during the next few days, and Melissa could become a hurricane on Thursday.

The forecast track of Melissa has been slightly altered with the tropical storm now expected to approach Jamaica, before turning towards the west on Saturday, and passing over the waters south of Jamaica, through the start of next week.

As the system nears Jamaica, it is expected to produce periods of moderate to heavy rainfall and strong, gusty winds, possibly reaching tropical storm intensity, particularly over northeastern and southern parishes on Thursday and continuing through the weekend.

Marine interests should expect widespread heavy showers and thunderstorms, along with tropical storm force winds late Wednesday and Thursday.

All small craft operators, including fishers from the cays and banks, should be arriving in port to start preparations for safe harbour.