Powerful Hurricane Erin is expected to bring high seas, big rip currents, and rough surf as it moves between the United States and Bermuda.

Hurricane Erin has been downgraded to a Category 3 hurricane but is gaining in size and raising the risk of life-threatening surf later this week along the U.S.

The storm has already prompted evacuation orders on North Carolina's Outer Banks and warnings about dangerous rip currents and swells along the East Coast.

Hurricane Erin's outer bands were beginning to lash the southeast Bahamas and the Turks and Caicos Islands early Monday after regaining Category 4 strength overnight.

Storms that ramp up so quickly complicate forecasting and make it harder for government agencies to plan for emergencies. Hurricane Erick, a Pacific storm that made landfall June 19 in Oaxaca, Mexico, also strengthened rapidly, doubling in intensity in less than a day.

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

The Ocean City Beach Patrol has closed the ocean to swimming, wading and surfing Tuesday as tropical storm activity off the coast brings dangerous conditions to the resort town.

While Erin is expected to take a northward turn in the Atlantic, a new system off the coast of Africa has the National Hurricane Center's attention.