Update: High surf warning issued for western shores of Big Island through Saturday

Update at 3:50 p.m. Nov. 29: A high surf warning is now in effect for the western shores of the Big Island until 6 p.m. Saturday as surf from a building extra-large northwest swell will exceed warning levels and peak tonight.

The National Weather Service forecast office in Honolulu says surf of 10 to 14 feet is expected along west-facing shorelines of North and South Kohala and North and South Kona.

Expect very strong breaking waves and powerful currents. Breaking waves might make navigating channels and channel entrances dangerous.

The weather agency advises the public to:

• Stay away from the shoreline along the affected coasts.
• Be prepared for road closures.
• Postpone entering or leaving channels affected by the high surf until the surf subsides.

Surf levels should begin to decline during the day Saturday.

Visit the National Weather Service Honolulu forecast office website for updated information about ocean and weather alerts.

Update at 1:32 p.m. Nov. 29: “Largest swell of the season so far will quickly build throughout the day today,” said the National Weather Service forecast office in Honolulu in an email this morning.

A sharp increase in surf is expected to come with that large to extra-large northwest swell fills in today and peaks tonight.

That’s why the National Weather Service forecast office in Honolulu issued a high surf advisory for the island’s western shorelines Thursday in advance of the swell. The advisory is in effect until noon Saturday.

However, offshore buoys were showing larger than expected swell heights this morning.

Forecasters now anticipate warning level surf of 8 to 14 feet tonight and into Saturday for west-facing exposures along select Kona shores, which means the potential for very strong breaking waves and powerful currents.

The day started off with surf of 3 to 5 feet along western shores. The forecast calls for surf increasing to 7 to 10 feet this afternoon and tonight, but as previously noted, greater heights can be expected.

Surf heights also can vary significantly from beach to beach, and surf larger than the upper end of the range provided in the forecast will occur periodically, sometimes up to a few hours apart.

Expect ocean water surging and sweeping across beaches, potentially impacting coastal properties and infrastructure, including roadways.

There also is the potential for brief overtopping of vulnerable coastal roadways and some wave runup to coastal properties near high tide early Saturday morning.

For the latest beach hazard and safety information at individual beaches, click here.

A gradual downward trend will follow over the weekend.

The National Weather Service forecast shows surf for the Big Island’s western shorelines falling just below or right at advisory level from 6 to 8 feet by Saturday morning and then to below advisory level at 4 to 6 feet that afternoon and evening.

Visit the National Weather Service Honolulu forecast office website for updated information about ocean and weather alerts.

Original post at 3 a.m. Nov. 29: Waters along exposed west-facing shores of the Big Island are about to get more than choppy as a large to extra-large long-period west-northwest swell drives surf heights up today.

The National Weather Service forecast office in Honolulu issued a high surf advisory from noon today through noon Saturday for Kona and Kohala shores because the swell, which has a strong westerly component, will continue to build into Saturday and likely produce advisory level surf as early as this afternoon.

Surf heights of 6 to 8 feet can be expected, causing strong, breaking waves and strong currents that will make swimming and other activities dangerous.

The long-period northwest swell is expected to peak late tonight or early Saturday before gradually declining.

National Weather Service forecasters said a small craft advisory would be issued if seas reach levels greater than 10 feet in the majority of coastal waters today and Saturday.

There also is the potential for brief overtopping of vulnerable coastal roadways and some wave runup to coastal properties near high tide early Saturday morning.

The public is advised to heed all advice from ocean safety officials. If you’re ever in doubt, the best option is don’t go out.

Forecasts from the National Weather Service for other shores around the island show surf along east and northeast shorelines will be remain elevated through the weekend because of a lingering short-period north-northeast swell.

South-facing shores will have near seasonal average surf for the rest of this week, driven by a mix of short-period southeast and background long-period south-southwest swells.

An upward trend is expected this weekend through the first week of December along southern shorelines, however, because of an active pattern developing within the swell window near New Zealand.