Swell Forecast & Schedule

Report Date: Thur. November 119, 2009
Forecast Source: NWS and NCDDC.

Surf Zone Forecast

National Weather Service- Honolulu, HI

HIGH SURF ADVISORY FOR EAST FACING SHORES

Surf along east facing shores will be 7 to 9 feet tonight and 5 to 8 feet Thursday.

Surf along north facing shores will be 6 to 10 feet tonight, decreasing to 5 to 8 feet on Thursday.

Surf along west facing shores will be 2 to 3 feet through Thursday.

Surf along south facing shores will be 3 to 5 feet through Thursday.

Outlook through Tuesday Nov 24: rough and choppy surf will continue along east facing shores into the weekend. A moderate north swell today will diminish Thursday and Friday, before a small north swell arrives Saturday. A larger northwest swell will build Sunday, and continue into Tuesday, with peak surf heights near advisory levels along north and west facing shores. A small south swell will continue for the next several days. 

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: rough windswell to continue with moderate episodes from north and south.

Detailed: mid Monday on northern shores has tiny to small breakers for locations exposed to refracted easterly windswell. More of the same is expected into Tuesday as a small episode fills in.

The jet stream has had a blocking pattern centered on the dateline and a trough in the gulf of Alaska, making for below average NW swell and above average local trades and windswell. More of the same is expected this week.

A weak low pressure system tracked east along the Aleutians crossing the dateline last Friday. Quikscat showed weaker winds than earlier anticipated. With the sub-gale speeds and travel distance over 1800 nm, only a tiny to small episode is expected locally from 330-345 degrees building Tuesday afternoon and dropping on Wednesday.

The same system was steered to the SE and intensified in the gulf of Alaska about 1500 nm NNE of Hawaii on Sunday. A strong high pressure followed the system, making strong to near gale winds in the 340-360 degree band to within 900 nm of Oahu. Closer to the low, gales aimed at targets just east of Hawaii, though angular spreading should bring in some swell.

A moderate episode is expected to rise early Wednesday from 350-020 degrees. It should peak late Wednesday, dropping to small levels by mid Thursday, and fading out on Friday.

Models suggest a reinforcement low pressure to the NNE of Hawaii late Wednesday into Thursday, giving a similar, though smaller by a notch, episode on Saturday.

Mid Monday on eastern shores has marginally high levels with mokapu buoy showing a drop in wave heights and periods. Rough surf is expected to rise on Tuesday.

A strong high pressure is building to the north of Hawaii. Trades are expected to increase to strong levels on Tuesday into Wednesday, making for rough, low-end high breakers, much low than the gale-induced episode of last week. Models show wind speeds and seas to slowly subside on the weekend.

Mid Monday on southern shores has rising, long-period swell from 185-200 degrees. It should hold about the same on Tuesday.

A long wave jet stream trough to the east of New Zealand has steered a series of surface low pressure systems from the S to SE of New Zealand. The first in the series was the strongest with the northernmost reach to the fetch. Buoy 51002 shows increasing energy in the 15-16 second band on Monday. This episode should last into Wednesday.

Follow-up systems spaced about two-days apart were more compact but should be enough to keep above November average surf through the week from 180-200 degrees.

Into the long range, a broad, storm-force system in the Tasman sea this past weekend could make for small breakers from 208-220 degrees next Sunday. The system weakened as it moved SE of New Zealand on Monday November 16. It should be enough to keep small, long period breakers into mid week next week.

In the northern hemisphere, models show the blocking ridge over the dateline starting to break down later in the week. A storm-force system is expected off Kamchatka on Wednesday, crossing the dateline near the Aleutians on Thursday. This could give a moderate to near high episode from 325-345 degrees, building Sunday and peaking Monday. Models bring the trough in the jet stream east of the dateline early next week, suggesting a return to seasonal high surf from NW to NNW mid to late next week. Such a pattern would bring more variability from day to day for the local winds.

Long range forecasts are subject to low confidence.

This collaborative forecast will resume on Thursday, November 19.

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