Erin is the fifth named storm to develop during the Atlantic hurricane season, which started just over two months ago. Last week, Tropical Storm Dexter formed in the western Atlantic but didn't pose a threat to land. In early July, Tropical Storm Chantal made landfall on the Carolina coast, bringing deadly flooding to the region.

Tropical Storm Erin is tracking west over the open Atlantic Ocean on Tuesday and forecasters expect it to become the first hurricane of the Atlantic season this week.

The chances that the storm will make landfall in the U.S. have increased slightly after the path shifted south.