Erin formed in the eastern Atlantic Ocean on Monday and is strengthening as it moves westward. The NHC said there is still uncertainty about what impact it could have on states like Florida on the U.S. East Coast, as well as the Bahamas and Bermuda.

Tropical Storm Erin is forecast to strengthen into the first hurricane of the Atlantic season by Saturday morning and then become a major Category 3 hurricane by Sunday morning as it passes north of Puerto Rico. But as of now, Erin is not expected to pose a direct threat to the U.S.

Tropical Storm Erin is forecast to intensify into a hurricane as it brushes Puerto Rico, then turn north. Its impacts on the U.S. east coast next week are still uncertain.