Hurricane Erin neared North Carolina’s Outer Banks on Tuesday and threatened to whip up wild waves and tropical force winds.

Hurricane Erin strengthened overnight to a Category 4 hurricane and will make its turn to the north Aug. 18, according to the National Hurricane Center.

Though Hurricane Erin is not forecast to make landfall on the U.S., the storm’s rapid intensification has prompted increased emergency measures in North Carolina, and the Outer Banks are now under a s...