MIAMI (AP) — A third tropical storm has formed in the eastern Atlantic Ocean.

The National Hurricane Center in Miami said Sunday morning that Tropical Storm Isaac was centered about 1,540 miles (2,475 kilometers) east of the Windward Islands.

There are no coastal watches or warnings in effect, but officials say it is expected to become a hurricane by Monday.

The storm's maximum sustained winds are 50 mph (85 kph) and it is moving west at 8 mph (13 kmh).