Most of eastern North Carolina is under a tropical-storm warning as Hurricane Sandy churns northward in the Atlantic Ocean.

In its 5 p.m. advisory Friday, the National Weather Service upgraded the tropical storm watch into a tropical storm warning for coastal regions of eastern North Carolina, including Beaufort, Dare, Hyde, Craven, Pamlico, Carteret and Onslow counties.

A tropical storm warning means that tropical storm conditions are expected within the next 36 hours somewhere within the specified areas.

Hurricane Sandy’s sustained winds of up to 105 mph Thursday had declined to 75 mph to 80 mph by Friday. That trend could continue through the weekend, according to the National Hurricane Center in Miami. The hurricane killed at least 39 people during its trek through the Caribbean, according to media sources.

“We’re preparing for a hurricane, hoping for a nor’easter,” said John Pack, Beaufort County’s emergency-management director, on Friday afternoon.

Pack expects the worst of the storm to affect Beaufort County on Sunday and into early Monday morning. He advises county residents to limit their travel Sunday, especially Sunday night, to only necessary trips.

“We had a meeting of the (Emergency Operations Center) staff (Friday) morning. We went through our hurricane-preparedness checklist to see where we stood,” Pack said. “As part of that, we did a conference all with North Carolina Emergency Management. We had all the eastern counties on there discussing what they were doing. We made final preparations, as necessary, to open any and all of our shelters that we have.”

On Friday, Gov. Beverly Perdue was expected to sign a document declaring eastern North Carolina in a state of emergency, Pack said, adding “that gives an expansion of powers all the way down to the county level.” That allows her to deploy the N.C. National Guard.

The stage’s Emergency Operations Center was expected to open this morning, Pack said.

Sandy, a category 1 hurricane, is expected to remain off the North Carolina coast this weekend as it moves northward, but its large wind field is expected to produce significant effects. Those effects include the following:

• Heavy rain resulting in flooding caused in part by poor drainage east of U.S. Highway 17. Expect 4 to 6 inches of rainfall east of U.S. 17, with some areas getting up to 8 inches.

• Coastal areas will experience sustained winds of 35 mph to 55 mph with gusts from 50 mph to 70 mph. Inland winds will experience winds from 20 mph to 30 mph with gusts to 40 mph.

• Along the southern Pamlico Sound, expect coastal flooding, rough surf and overwash from 3 to 5 feet.

Although it’s expected to be east of Cape Hatteras about 2 a.m. Monday, rain and wind associated with the storm will affect the region today and Sunday.

The county’s EOC staff meets again at noon today to revise its threat assessment as Sandy draws nearer to North Carolina.

The Eastern North Carolina Region of the American Red Cross is mobilizing volunteers, shelters relief supplies and disaster vehicles from chapter offices in Washington, Wilmington, Jacksonville, New Bern, Greenville, Elizabeth City, Kinston, Goldsboro, Rocky Mount and other staging sites to support the response and relief efforts in affected areas along the coast. Additional support staffs are being prepositioned in locations near the Outer Banks, where a greater potential for flooding is expected.

“Hundreds of local Red Cross volunteers are on standby and will be ready to assist in their communities,” said Autum Mihm, spokeswoman for the American Red Cross, in a news release. “The best thing families can do is to get ready now by staying informed about Sandy’s progress, listening to the advice of local authorities, checking their emergency supplies and reviewing their household’s emergency plan.”

Across the mid-Atlantic and Northeast, the Red Cross is moving disaster workers into areas that weather experts said would be affected by the storm. It has more than 100 emergency response vehicles on alert. The Red Cross is working closely with government officials, as well as community partners to coordinate response efforts, according to a news release.