Update: Incoming largest swell in overlapping winter-caliber series calls for extension of high surf warning, advisory

Update at 12:37 p.m. Dec. 21: The high surf warning in effect for the shores of Kona and Kohala on the Big Island was extended again, this time until 6 a.m. Dec. 23, as the National Weather Service in Honolulu is forecasting surf to reach peak heights of 8 to 12 feet through the day Sunday.

The best chance for coastal impacts to properties and roadways will be during peak daily high tides through the early morning hours.

Impacts from the high surf could be very high.

Forecasters say ocean water could surge and sweep across beaches, coastal benches and lava flows, creating the potential for impacts to coastal properties and intrastructure, including roadways.

Large breaking waves and strong currents will be present at most beaches and could impact harbor entrances and channels, causing challenging boat handling.

The public is advised 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.

The high surf advisory in effect for the island’s north-facing shores also was extended through 6 a.m. Dec. 23, with National Weather Service forecasters expecting surf of 12 to 16 feet along those shorelines.

Strong breaking waves and strong currents will make swimming and other ocean activities dangerous in these areas as well. The public should heed all advice from ocean safety officials.

In all high surf situations, remember: when in doubt, don’t go out.

This extended period of hazardous surf and beach conditions — which will persist into early next week along exposed north and west shores — is being caused by overlapping, winter-caliber north-northwest swells moving through the islands.

The largest swell in the series is expected to arrive tonight, rapidly rise early Sunday, peak through the day and then gradually ease Sunday night into early next week.

Surf associated with this swell will remain well above warning levels through the weekend, then return to advisory levels for north and west shores by about Tuesday.

Because of the high surf warning and advisory, Hawai’i County Civil Defense reports that the following beaches are closed:

• Kahalu‘u Beach Park, Kailua-Kona.
• Onekahakaha Beach Park, Hilo.
• James Kealoha Beach Park, Hilo.
• Leleiwi Beach Park (Wai‘uli), Hilo.
• La‘aloa Bay Beach Park a.k.a Magic Sands (no ocean entry), Kailua-Kona.

Beaches will remain closed through Sunday. Others could close without notice.

For more information about weather and other hazards, visit the Hawai‘i Hazard Impact Map.

Update at 5:11 p.m. Dec. 20: The high surf advisory that was in place for Kona and Kohala shores of the Big Island has been replaced with a high surf warning that is effect until 6 p.m. Sunday.

According to the National Weather Service in Honolulu, a series of large northwest-to-north-northwest swells will move through Hawaiian waters during the weekend and into early next week.

Surf of 10 to 14 feet is expected along west-facing shores.

Warning-level surf will prevail along north and west shores of the smaller islands through the weekend, with a brief dip possible late Saturday and Saturday night.

Warning-level surf will prevail across west-facing shores of the Big Island, while advisory-level surf is expected along north-facing shores.

The high surf advisory for north shores of the island also was extended until 6 p.m. Sunday.

Update at 5:42 a.m. Dec. 20: The National Weather Service in Honolulu has extended a high surf advisory in effect for the Big Island to now include north-facing shores. The advisory, which was originally issued for western shores of the island, also was extended until 6 p.m. Saturday.

North-facing shores of the island are expected to see surf of 15 to 20 feet today, building to 18 to 24 feet tonight and Saturday. Surf of 6 to 8 feet is forecast for western shorelines of the island.

A series of large northwest to north-northwest swells will continue to move through Hawaiian waters during the weekend and into early next week.

Advisory level surf is expected to hold in place through late Saturday afternoon.

Strong, breaking waves and strong currents will make swimming and other ocean activities dangerous. Heed all advice from ocean safety officials.

When in doubt, don’t go out.

National Weather Service forecasters in Honolulu say the largest of the swells will arrive late Saturday night into Sunday.

This swell is expected to bring the largest surf of the season so far to north-facing shores Sunday.

Original post at 7:49 p.m. Dec. 19: A series of large northwest to north-northwest swells is moving through Hawaiian waters and will continue into Monday.

With the overlapping pulses of swells likely to produce advisory level surf along western shores of the Big Island, the National Weather Service forecast office in Honolulu has issued a high surf advisory for Kona and Kohala coastlines in effect until 6 a.m. Saturday.

Large breaking waves of 7 to 10 feet along west-facing shores are expected, causing strong currents and making swimming and other ocean activities dangerous.

The National Weather Service area forecast discussion for Hawai‘i from 3:49 p.m. Thursday said long period northwest energy was expected to reach the Big Island by tonight.

The public is advised to heed all advice from ocean safety officials. When in doubt, don’t go out.