A new northwest swell was beginning to generate big waves yesterday afternoon along north- and west-facing shores of Ni'ihau, Kaua'i, O'ahu and Moloka'i, and on west-facing shores of Maui.

The National Weather Service issued a high-surf advisory that is expected to remain in effect until 6 a.m. Friday.

Ni'ihau and Kaua'i was to get 15- to 18-foot surf on their north shores, the weather service said. Similar surf was expected to build on O'ahu and Maui through the evening.