Forecasters say Tropical Storm Erin, which formed in the eastern Atlantic Ocean on Monday, is expected to become the Atlantic's first hurricane of the season. The storm formed just west of the Cabo Verde islands, off the western coast of Africa, and was moving west, the U.S. National Hurricane Center in Miami said.

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

Tropical Storm Erin has formed on a path toward the Caribbean and is expected to strengthen to a hurricane later in the week as it passes by Puerto Rico. Most models forecast the storm turning upward into the Atlantic Ocean, but a few see the storm continuing onward to the U.S. mainland.