Two more tropical systems trail Hurricane Erin, which is following a projected course that brushes past the East Coast without making landfall.

Mandatory evacuations are underway for parts of the Outer Banks, including Dare and Hyde counties and various islands, as Hurricane Erin draws closer.

Forecasts nudge Erin's likely path to the west, increasing the risks at U.S. beaches. Experts say the storm's massive size, rather than windspeed, is what makes it a threat.

By Tuesday morning, Erin had lost some strength from previous days and dropped to a Category 2 hurricane with maximum sustained winds of 110 mph (175 kph), the National Hurricane Center in Miami said.

Hurricane Erin was a Category 4 storm Monday morning and is expected to retain major hurricane status through the middle of the week.

Hurricane Erin is moving east of the U.S. coast and will bring strong waves and rip currents to Florida's east coast – and it comes as the National Hurricane Center is eyeing two more tropical waves in the Atlantic.