The National Weather Service issued a high surf advisory at 4 a.m. today for the north-facing shores of Niihau, Kauai, Oahu, Molokai and Maui.

The advisory is expected to remain in effect until 6 a.m. Wednesday.

A swell generated by a storm passing by to north of the islands several days ago has begun to arrive, the Weather Service said.

Data from several ocean buoys suggest the surf heights will be at, or slightly above, the advisory level of 15 feet for north-facing shores.

The above normal north-northwest swell is expected to last through early Wednesday morning.

Elsewhere on Oahu today, look for surf of 6 to 9 feet along west-facing shores, 5 to 7 feet along east-facing shores and 2 feet or less along south-facing shores.

Outlook through Sunday, Feb. 8: The north-northwest swell will peak near the 15-foot north shore advisory level today and tonight.

A long period northwest swell will boost surf above advisory levels again Thursday night into Saturday.

Fresh trade winds and an increasing north-northeast swell will produce rough, short period surf near the advisory level along east-facing shores over the next few days.