Tropical wave Invest 98L remains with a 90% probability of development for the next 48 hours.
According to the National Hurricane Center, the system will probably turn into a tropical depression in the next few days and it is expected that approach Puerto Rico this weekend.
The low pressure system is located about 1,000 miles east of the Windward Islands, in an area favorable for tropical development and moving west-northwest.
The CNH warned that tropical storm watches could be issued as early as tonight for some islands in the Antilles.
"It is possible that there will be heavy rains locally, regardless of the strength of the system, which that could cause flash floods, "the center noted.
Rains and strong winds from this system could reach parts of the eastern Caribbean, including Puerto Rico and the Virgin Islands.