North Shore residents should be prepared to evacuate this weekend while surf as high as 60 feet could wrap around Oahu all the way to Makapuu and Diamond Head, city officials said Friday.

And everyone should tie down loose objects at home and be aware that high winds could topple power lines and trees while sending debris flying through the air.

“Be flexible with your travel plans this weekend as the highways could be impacted, roadways could be impacted,” said Hirokazu “Hiro” Toiya, director of the city’s Department of Emergency Management.

“National Weather Service is telling us they haven’t seen a pattern like this in some time,” Toiya said. “We don’t exactly know what the impacts will be, but the potential is significant. So for those folks that are living on the North Shore, we would urge them to be vigilant and be prepared for the possibility that they may need to evacuate their homes.”

If so, the city likely will open evacuation centers, he said.

The National Weather Service predicted surf as high as 25 to 35 feet for today and 40 to 60 feet for Sunday along north- and west-facing shores of Niihau and Kauai, and north-facing shores of Oahu, Molokai and Maui.

At the same time, wind gusts of over 50 mph could develop today. And sustained west winds of over 40 mph — with gusts over 60 mph — are possible for some areas tonight through Sunday night.

If power lines should fall on a moving vehicle, Toiya urged drivers to remain calm, pull over, call 911 and wait for help.

“Help is going to come,” he said. “Let the professionals handle it.”

The state Department of Land and Natural Resources warned of “a major storm headed toward Hawaii that could bring destructive coastal flooding and erosion and high winds.”

DLNR’s Division of Boating and Ocean Recreation advised boaters to secure their vessels — whether they’re in small-boat harbors or tied to offshore moorings.

At the same time, the Division of State Parks warned coastline campers “to move out of harm’s way if necessary.”

“This could be a powerful storm, and along with all of our federal, state and county partners, we can’t stress strongly enough, that anyone living or playing along coastlines should pay attention to the latest weather advisories and warnings to be sure they stay safe,” DLNR Chairwoman Suzanne Case said in a statement.

Maui’s Department of Parks and Recreation officials were preparing for the possibility of shoreline flooding, dangerous ocean conditions and “damaging winds.”

Maui officials are expecting downed trees islandwide and the “potential for hurricane-force winds at high elevations.” So county officials warned Maui residents and tourists to stay away from streams, drainage ditches and low-lying areas prone to flooding. People also should not cross fast-flowing or rising water in vehicles or by foot.

On Oahu, Jim Howe, director of the city Emergency Services Department, said lifeguards will be warning people to stay away from the shoreline.

“This is for visitors in particular who may not be familiar with the kinds of conditions we see here in the islands when we get a big surf episode,” Howe said. “For those folks that are visiting the island, this isn’t the kind of surf you’re going to go and get a picture of one of our famous big-wave surfers. Nobody’s in the water on the North Shore right now. It’s too rough. It’s not a great time to head out to the North Shore and think you’re going to get that picture or see that famous Hawaiian surf that everyone wants to see.”