Swell Forecast & Schedule

Report Date: Mon. March 15, 2010
Forecast Source: NWS and NCDDC.

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Surf Zone Forecast

National Weather Service- Honolulu, HI

HIGH SURF ADVISORY FOR NORTH AND WEST FACING SHORES

Surf along north facing shores will be 18 to 24 feet today then drop to 14 to 18 feet Tuesday.

Surf along west facing shores will be 12 to 16 feet today then drop to 8 to 12 feet Tuesday.

Surf along east facing shores will be 2 to 4 feet today then build to 3 to 5 feet Tuesday.

Surf along south facing shores will be flat to 2 feet today then build to 2 to 3 feet Tuesday.

Outlook through Sunday Mar 21: the current northwest swell is topping out over 20 feet this morning and will gradually diminish into Tuesday, but remain in the advisory range through Tuesday night. North facing exposures will remain elevated at or near the advisory level through most of the period. South facing shores will see a slight bump over the next two days with a much larger increase expected for the weekend. Surf will reach a few feet overhead for top south facing breaks this weekend gradually diminishing into the first half of next week.

Surf heights are forecast heights of the face or front of waves. The surf forecast is based on the significant wave height, the average height of the one third largest waves, in the zone of maximum refraction. Some waves may be more than twice as high as the significant wave height. Expect to encounter rip currents in or near any surf zone.

Collaborative Nearshore Forecast for Oahu

NWS/NCDDC- Honolulu, HI

This collaborative forecast will be updated Monday through Friday at 300 pm when Pat Caldwell is available. When Pat Caldwell is not available, the latest collaborative forecast will remain posted for 4 days.

Surf heights will vary between different beaches and at the same beach at different break areas.

Summary: northern shores return to winter mode for last week of winter.

Detailed: mid Friday on northern shores has small breakers from mostly refracting windswell. A small increase is expected on Saturday.

A zonal jet stream across the central north Pacific has kept lower than winter average surf over the past week. The jet is gaining a more meridional pattern, or north to south trough features, for this weekend into the long range, signaling a return to average to above average late winter-early spring surf.

The last system in the zonal pattern did not strengthen until past the longitude of Hawaii on Tuesday. Marginal gales aimed at targets just NE of Hawaii. From the near gales aimed at Hawaii in the 330-350 degree band, and from angular spreading from swell missing Hawaii to the immediate northeast, an upper-end small episode is expected locally, building Saturday and dropping Sunday from 330-000 degrees.

A storm-force system formed near Japan late Wednesday. It tracked east along about 45°N into Friday. Over the first 36 hours, the fetch favored the 305-320 degree band. The jason altimeter validated well model output from Wave Watch III for 18Z Thursday showing seas greater than 30 feet in an area about 2400 nm away from Hawaii. Best estimates from models and observations suggested a minor weakening to the seas as the fetch approached the dateline on Friday morning, with mostly 25-28 feet waves.

Long period energy from 305-320 degrees is expected to arrive locally Sunday afternoon, building to high levels overnight Sunday. Surf from this direction should stay moderate to high Monday and decline on Tuesday.

The broad extratropical cyclone has crossed the dateline on Friday. Models show it tracking toward the gulf of Alaska on Saturday, with gales to storm force winds over a long, yet duration-limited fetch in the 320-340 degree band. The head of the fetch could reach within 1000 nm of Hawaii on Saturday morning. Due to proximity, surf from this source should represent the peak of the episode, building early Monday, peaking Monday afternoon in the high to marginally extra-large bracket, and slowly dropping Tuesday.

Models show the system occluding in the gulf of Alaska on Sunday, as the track of the low pressure center stalls. Similar magnitude of winds are expected for another 36 hours in the 340-010 degree band Sunday into Monday with the head of the fetch about 1200 nm away, stretching to Alaska. Energy from this directional band should build to high levels late Tuesday, holding at marginally high levels on Wednesday, with a slow decline.

Mid Friday on eastern shores has moderate to near high breakers. The mokapu buoy shows the dominant period remaining at the high end for windswell at 9-10 seconds. Models suggest a steady decline in wave height, though a slower decline in wave period. Surf should hold in the moderate category on Saturday from 60-90 degrees, dropping to small levels on Sunday.

See the latest NWS state weather forecast discussion for explanations on the changing wind patterns. Fresh or stronger breezes on Monday could return rough, moderate breakers from 30-60 degrees, dropping on Tuesday.

Mid Friday on southern shores has small, long-period breakers. It was generated by gales SE of New Zealand a week ago Wednesday into Thursday. This episode should be short-lived.

Refracting easterly windswell is also affecting select southern surf zones. More of the same is expected Saturday, dropping off Sunday.

A low pressure system occluded south of Tahiti this past Tuesday with storm-force winds aiming swell north centered on about 145°W. Angular spreading could bring in low, long-period swell locally next week, making for small breakers starting Tuesday from 160-180 degrees.

Into the long range, a meridional jet stream pattern is expected off and on over the next 10 days east of New Zealand, with gale to storm-force surface low pressure systems moving into the favorable source zone for Hawaii. Back to back episodes are expected, with the first one arriving roughly March 21. Peaks of episodes could reach moderate to high levels with most days small to moderate from 180-200 degrees.

In the northern hemisphere, models suggest the jet stream remaining at active late winter-early spring mode with troughs in the northwestern to central north Pacific dipping toward the subtropics. This should mean an above average pattern for the end of March with peak days at marginally high and most days small to moderate. Such a pattern with give changes to the local wind pattern every few days.

Long range estimates are subject to major revisions.

This collaborative forecast will resume on Wednesday, March 17.

This forecast was produced through the collaborative efforts of NWS Forecaster DEJESUS and Pat Caldwell , Pacific/Hawaii Liaison Office, NCDDC