Preliminary data from an Air Force plane showed Earl could be restrengthening and may grow into a Category 4 hurricane later Wednesday, the National Hurricane Center said.

Mandatory evacuation orders were issued for Ocracoke Island, on North Carolina's Outer Banks, and Cape Lookout National Seashore, as well as for visitors to Hatteras Island.

Earl was downgraded to Category 3 early Wednesday, but was still a major hurricane. National Hurricane Center Director Bill Read told reporters that the cyclone's 10-mph reduction in winds was a "fluctuation" rather than a true weakening of intensity. CNN meteorologist Chad Myers compared it to Hurricane Katrina, which brought severe damage to the Gulf Coast when it slammed ashore as a strong Category 3 hurricane in 2005. [ NOAA ]