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.

Forecasters say Erin will likely become a hurricane by late Thursday and a major hurricane by early Sunday, but it's still too early to determine what sort of impacts the storm could have, if any, on the U.

Tropical cyclones become tropical storms when sustained winds reach 39–73 mph, are upgraded to hurricanes at 74 mph, and become “major” hurricanes at 111 mph or higher, corresponding to Category 3–5 on the Saffir-Simpson Hurricane Wind Scale.