Island communities off the coast of North Carolina are bracing for flooding ahead of Hurricane Erin, the year’s first Atlantic hurricane.

Additional strengthening is expected as the storm is forecast to “remain a large and dangerous major hurricane through the middle of this week,” the National Hurricane Center said.

Parts of North Carolina's Outer Banks are under mandatory evacuation orders, as the National Hurricane Center warns that Hurricane Erin could bring tall waves topping 15 to 20 feet.

Maximum sustained winds have increased to near 140 mph, with higher gusts. Erin is a Category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale. Some additional strengthening is expected today. Erin will remain a dangerous major hurricane through the middle of this week.

Hurricane Erin is likely to restrengthen again as it passes east of the Turks and Caicos Islands and the southeast Bahamas on Monday after lashing the Caribbean with damaging winds and flooding rain.

Hurricane Erin weakened to a Category 3 hurricane overnight but still remains a formidable major storm.Erin had max sustained winds of 125 mph, the National Hurricane Center said in an update on Sunday afternoon.