Hurricane Erin isn't forecast to hit land, but it will bring large waves and dangerous rip currents to the U.S. East Coast this week.

Offshore Hurricane Erin was downgraded to a Category 3 storm early Sunday, as rain lashed Caribbean islands and weather officials warned of possible flash floods and landslides.It also warned of "locally considerable flash and urban flooding,

Hurricane Erin has intensified to a Category 4 storm affecting the Caribbean, impacting flights and cruise itineraries, with warnings issued for the Bahamas and Turks and Caicos, and it poses a significant coastal threat to the U.

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Forecasters are watching a new tropical system that may form behind Hurricane Erin, which is intensifying again Monday as it tracks off the U.S. coast.

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.