Tropical storm Ida has formed in the southwest Caribbean, quickly adding muscle and prompting storm warnings for the coast of Nicaragua and two Colombian islands.

The National Hurricane Center in Miami said the ninth tropical storm of the season took shape Wednesday afternoon. Maximum sustained winds have increased to near 60 mph (95 kph).

The storm's center is about 75 miles (120 kilometers) east of Bluefields, Nicaragua. It is moving toward the northwest near 6 mph (9 kph).

Storm warnings were in effect for the eastern coast of Nicaragua and the Colombian islands of San Andres and Providencia.