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CRAMP: North Pacific Swell

North Pacific Swell is generated by Northern Hemisphere winter storms in the North Pacific. Typical wave heights offshore range from 8-15 feet with periods of from 10-17 seconds. Breaking waves inshore with faces over 15 m (50 ft) high have occasionally been observed. North Pacific Swell has a dominant NW directionality (315°) that can vary between 282° and 45°. Wave energy of this magnitude prevents extensive coral reef development along the north shores of the Hawaiian islands.

1. Typical Conditions

Northern hemisphere winter storms generate North Pacific Swell that typically arrives in Hawai‘i from the northwest. WAM model nowcast data for 29 December 2000 from NOAA/NCEP website. (Click for a larger view)

Typical conditions for generation of North Pacific Swell, WAM model nowcast data observed on 17 January 2001. Data from NOAA/NCEP website. (Click for a larger view)

2. Changes in Normal Directionality

Directionality of the North Pacific Swell can vary. Under very unusual conditions the North Pacific Swell can even arrive from the east. Wave data provided by Naval Oceanographic Office website. (Click for a larger view)

The Mokapu wave buoy located off NE O‘ahu measured the unusual period of eastward swell on 24 Jan 2001. Data provided by Pat Caldwell of NODC. (Click for a larger view)

Model data shows conditions responsible for easterly swell in Hawai‘i on 25 Jan 01. Data from NOAA/NCEP website. (Click for a larger view)

November - December 2000 Wave Gallery



Last Update: 04/21/2008

By: Lea Hollingsworth

Hawai‘i  Coral Reef Assessment & Monitoring Program

Hawai‘i  Institute of Marine Biology

P.O. Box 1346

Kāne‘ohe, HI 96744

808-236-7440 phone

808-236-7443 fax