The US National Hurricane Centre in its 8 a.m. tropical storm update reported Tropical Storm Isaac's centre was 25 miles east of Dominica and 80 miles southeast of Guadeloupe.
Winds will likely diminish over land, but the storm's path, which now looks set to make landfall near the North Carolina-South Carolina border, will still take it as far west and south as the Georgia border, the analytics firm predicted.
Tropical storm watches are in effect for Montserrat, St. Kitts and Nevis, Antigua, and Saba and St. Eustatius.
For its part, the tropical storm Helene, located southwest of the Portuguese Azores, has tilted its course to the north and must be maintained with a similar course and speed of translation over the waters of the eastern Atlantic.
This weekend Isaac is forecast to move toward the central and western Caribbean as a tropical storm.
Tropical Storm Isaac continued west at 15 miles per hour with maximum winds of 60 miles per hour as of 5:00 a.m. Wednesday.
Little change in strength is expected over the next several hours as Isaac moves through the Leeward Islands.
An outer band associated with Isaac will bring some scattered showers and possible isolated thunderstorms to Barbados today.
For this reason, all warnings and storm surveillance for the Lesser Antilles have been raised. If the two systems become tropical storms, it would be the first time the Atlantic has had five named storms at once, Colorado State University meteorologist Phil Klotzbach said.
The Portuguese Sea and Atmosphere Institute said "very strong wind from the south with gusts up to 120km/h, heavy rain and waves from the south between 6 and 8m high are expected from Thursday afternoon to Sunday" in Flores and Corvo islands.
This alert is provided by Tropical Storm Risk (TSR).