Sometime late tonight, the first of four big swells over the next week will begin hitting North Shore reefs. The National Weather Service predicts wave faces of 20 to 30 feet that will rise quickly and dramatically.

A second swell is expected Monday, a third one on Thursday that could reach 40 feet and a fourth swell next Friday or Saturday.

The swells were the only topic of conversation at Sunset Beach yesterday, said Waimea Bay resident Jodi Young.

"It’s always really exciting," she said. "Your bed shakes against the wall. You can hear the rocks being moved around underwater. The place does rattle and roll, no two ways about it."

But waves this large are dangerous, even for people who never set foot in the ocean. Young said she will probably move backyard furniture and other loose objects so they won’t be swept out to sea.

Henry Lau, a marine forecaster for the weather service, said residents should be ready for "a rapid, sharp rise" in surf heights sometime after midnight and before sunrise.

"That can catch people off-guard," he said. "That is the dangerous type. We’re looking at 20 to 30 feet. There is a very good chance that it will wash up on beaches."

In anticipation, the weather service issued a high surf warning this morning for northwest facing shores of all islands. Although the largest of the surf will hit northwest shores on O'ahu and Kaua'i, wave faces from 15 to 25 feet are expected on northwest facing shores of all other islands.

North Shore lifeguards are bracing for impact.

"We’re battening down the hatches," said lifeguard Lt. Pat Kelly, a veteran of many North Shore winters. "Anybody who has been around this winter and hasn’t seen it, this will be the first series of events in the extra-large category."

People wanting to see the waves should avoid beaches without lifeguards and areas close to the ocean, he said. Because not every wave is large enough to wash ashore, people are lured to the edge and can be swept to their deaths when a larger wave arrives, Kelly said.

Southwest winds could wreak havoc on the waves for surfers, he said, although sometimes they just miss North Shore spots.

"It could be big and glassy enough to hold the Eddie Aikau," he said.

And if big waves are on North Shore minds, "the Eddie" is just a half-thought behind.

Young, who helps organize The Quiksilver in Memory of Eddie Aikau Big Wave Invitational, said she has been getting telephone calls for the past two days from surfers as far away as Australia. They’re ready to catch the first flight to Hawai'i, she said.

The contest is only held when 20-foot open ocean swells produce wave faces of 30 feet or more at Waimea Bay.

"One of these swells could potentially be an Eddie swell," she said. "There is anticipation. The residents are the first to think about it and from there, the word goes out. It is around the world already."