North shore waves were expected to reach 18 to 22 feet last night and drop to 12 to 16 feet this morning just before another northwest swell hits, the National Weather Service said.

A new incoming swell tomorrow and Friday is expected to generate warning level surf along north- and west-facing shores, then drop through the weekend, the weather service said.

Yesterday a large wave at Pipeline on O'ahu's North Shore wiped out a male surfer in his 20s, who hit the reef, according to Bryan Cheplic, spokesman for the city's emergency services department. City lifeguards rescued the surfer. He was treated by city paramedics and taken in stable condition to a local hospital, Cheplic said.

Lifeguards along Waimea Bay and Ehukai Beach Park made eight rescues yesterday and used their personal watercraft to assist in five other rescues, Cheplic said.

He urged people to always swim at a guarded beach and consult a lifeguard about ocean conditions before going into the water.

For more information regarding ocean conditions, advisories, and warnings, the Ocean Safety and Lifeguard Services Division provides a pre-recorded report that can be accessed 24 hours a day at 922-3888, ext. 51, or visit: www.hawaiibeachsafety.org.