Hurricane Erin will continue to strengthen as it approaches the Leeward Island and Puerto Rico, where it will threaten with tropical downpours, pounding surf and strong winds.

Tropical Storm Erin was expected to strengthen into a hurricane on Friday as it approached the northeast Caribbean, prompting forecasters to warn of possible flooding and landslides. The storm is expected to remain over open waters,

Erin, the first hurricane of the season, is now forecast to become a Category 4 by Sunday. Here's where it could head in the week ahead.