A large northwest swell has prompted a high surf advisory for north and west facing shores of most islands from 6 p.m. Thursday through 6 a.m. Saturday.

The National Weather Service expects surf on north shores to be 10 to 14 feet Thursday, rising to 12 to 16 feet Thursday night and 15 to 20 feet on Friday.

West shores can expect wave faces of 6 to 10 feet Friday, building to 8 to 12 feet Thursday night and 10 to 14 feet Friday.

South shores are also expecting a small swell to bring 3 to 5 feet surf, but not reaching advisory levels of 8 feet.

East shores may also see a bump from increased tradewinds with waves of 2 to 4 feet.

Forecasters say beachgoers can expect strong breaking waves and shorebreak. Rip currents can also make swimming difficult and dangerous.

Beachgoers should heed advice from lifeguards and exercise caution, the National Weather Service said.