The National Hurricane Centre (NHC) says a tropical wave near Trinidad and Tobago is likely to turn into a tropical storm in the next few days.
In an update at 11 pm Saturday, the NHC confirmed the latest development.
"A strong tropical wave, accompanied by a broad low pressure area located between Barbados and Tobago, is producing showers and thunderstorms that are showing signs of organization," the HC said.
It added: "In addition, recent satellite-derived surface wind data and observations from Barbados indicate that the disturbance is producing winds to near tropical storm force in the eastern portion of the system. Further development of this disturbance is expected over the next couple of days, and a tropical depression or tropical storm will likely form while it moves westward and then northwestward at 10 to 15 mph across the Windward Islands and over the eastern Caribbean Sea."
The NHC said the system is then expected to turn northward, moving near Puerto Rico and the Virgin Islands on Tuesday.
Regardless of development, heavy rainfall and strong gusty winds are likely over much of the Lesser Antilles during the next couple of days and will likely spread across Puerto Rico and the Virgin Islands by Monday night or Tuesday, it added.
It notes that interests across the eastern Caribbean should monitor the progress of this disturbance since tropical storm watches and warnings could be required for portions of the Lesser Antilles and Puerto Rico and the Virgin Islands on Sunday.
Earlier today the Met Office raised the alert level from yellow to orange.
It said that periods of heavy to intense showers and/or thunderstorms are likely.
It added that heavy/intense downpours are expected to result in street/flash flooding.
Gusty winds in excess of 65 km/hr can be expected and the risk of landslides/landslips is very high in areas so prone.
Sea conditions are also likely to become occasionally rough.
It has suggested that adequate preparations be made to safeguard life and property.
It says that people who live in areas that are susceptible to flooding, especially areas along the main river courses and tributaries, should be prepared and create a safety plan in case of emergency.
Meanwhile, another tropical wave is expected to move off the west coast of Africa by Sunday and environmental conditions are expected to be conducive for development, and a tropical depression or tropical storm is likely to form early next week while the wave moves westward across the eastern tropical Atlantic.
This system has a high 90 per cent chance of development within the next five days.