Pat Caldwell

Hazards
No high surf advisory or warnings.
Forecast
Surf along east facing shores will be 3 feet or less through early Saturday, and 2 to 5 feet late Saturday. Surf along south facing shores will be 2 to 4 feet through Saturday. Surf along west facing shores will be 5 to 8 feet through Saturday. Surf along north facing shores will be 6 to 9 feet today and 6 to 8 feet Saturday.
Outlook
Outlook through Thursday September 3: a building west-northwest swell will peak late this afternoon into Saturday then gradually subside through Monday. Swell produced by hurricane Ignacio may increase surf to the high surf advisory threshold along east facing shores later this weekend. Surf may reach the high surf warning threshold along east facing shores early next week. The timing and size of this swell remains uncertain since it depends on the track and strength of the Ignacio as it approaches the islands. An increasing south swell is anticipated to arrive Thursday which could rise significantly Friday. 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, at the locations of the largest breakers. 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.
About Collaborative Surf
THIS COLLABORATIVE FORECAST WILL BE UPDATED MONDAY THROUGH FRIDAY AT 300 PM WHEN PAT CALDWELL IS AVAILABLE.
Collaborative Surf Discussion
Discussion: summary: Abundant surf from around the compass with another nearby tropical system making rough, above average surf starting Monday into Wednesday backing from ESE to N. Detailed: Mid Friday on northern shores has long-period surf from 290-300 degrees at levels above the late August average, which is 4 feet face for top sets. Heights should remain elevated on Saturday. Typhoon atsani has made a long-lived W component swell that started locally a week ago. The more W component from 260-280 degrees is dropping on Friday and should continue to decline on Saturday as the primary direction veers more to 285-305 degrees. Typhoon atsani turned NE into the NW Pacific 8/24-25 maintaining hurricane-force winds. It stalled near 40°N, 162°E or about 2200 nm away, 8/25-26 as it slowly weakened. The fetch was within 285-305 degrees, so Oahu is partially shadowed by Kauai, making for bigger error bars on local surf heights and larger gradients of surf size along the exposed coast depending on degree of shadowing. Noaa buoy 51101, 270 nm WNW of Oahu, showed a surge in wave energy in the 16-19 second band 4-9 am HST 8/28. This is likely the peak of the event, and with the 10 hr travel from this direction, should peak locally Friday afternoon. The event should be long lived, with similar surf on Saturday. The remnant of atsani 8/26-28 favored seas more north to south on the west side of the low pressure center, which moved NNW and weakened. The fetch towards Hawaii was short. This should mean the primary swell production was the 8/24-26 period, and dispersion of swell will dictate the decline as the local dominant wave period decreases Saturday into Monday. The direction should remain the same. A short-period event from 000-020 degrees picked up Friday as seen in the pacioos/cdip buoys off Waimea and mokapu on Oahu. A strong surface high pressure cell near the central Aleutians, and a surface trough over to just north of Hawaii, set up a band of fresh to strong trades between 28-32°N from 145-170°W. Angular spreading is giving the apparent N component locally. Similar conditions are expected into Sunday. A low pressure off oregon 8/26 had strong to marginal gale winds in an area beyond 1600 nm from Hawaii. This should bring up the dominant wave period from 000-020 degrees late Sunday into Monday with small breakers. It should be short-lived. Mid Friday on eastern shores has small breakers for N exposures for the source described above and near nil energy from 45-90 degrees. Similar surf is likely for Saturday. See the latest Central Pacific Hurricane Center, CPHC, products for details on hurricane Ignacio. Surf-wise, it is south of the Oahu shadow line created by the easternmost Hawaiian islands. The 11 am HST 8/28 CPHC forecast track keeps Ignacio in the shadow until late Sunday or Monday. As with all forecasts of tropical cyclones, confidence beyond two days is low and estimates in the above table are subject to change. Stay tuned for updates. As a ballpark comparison, the forecast track is similar to Guillermo that had a peak in local E to NNE surf 8/5-6. Guillermo decreased sharply once in the Oahu window. Models are suggesting Ignacio to stay stronger and create higher surf. Stay tuned for validation for specifics Monday into Tuesday. Surf should be a combination of the windswell of more N to NE component, and longer period swell from ESE to ENE. The combined effect makes for rough conditions with confused breakers and strong currents. During the ESE phase as noted in the table above,. Differences in the shadow along the east shore lead to larger breakers further north. Coastal wave wash is expected to be above average during the higher tides late Monday to Wednesday for E to N exposures. Hurricane Jimena is strengthening 8/28 in a location beyond 2000 nm to the ESE of Hawaii. The forecast track keeps the system north of the Oahu shadow line. Long period forerunners are modelled to fill in locally late Tuesday from 95-110 degrees, with surf climbing above average by Wednesday. It is too early for specifics. Mid Friday on southern shores has breakers from a mix of sources within 170-280 degrees. Heights are expected to lower on Saturday. A low S of French Polynesia 8/18-20 is providing moderate-period SSE surf on 8/28, and severe gales from SE of New Zealand at about the same time are providing the longer period SSW surf on 8/28. The former should fade out Saturday as the latter slowly declines. Small short- to moderate-period breakers from 230-250 degrees were created by tropical system Kilo. It should stay about the same into early next week. Kilo is strengthening as it moves west, and wave models are showing a slight increase in dominant wave period and height from Kilo from 250-270 degrees Tuesday into Wednesday 9/1-2. A marginal gale east of New Zealand had a fetch about 3000 nm away 8/21-23. This should keep a small event Sunday into Monday from 180-190 degrees. A fast-moving severe gale SE of New Zealand 8/25-26 could bring an event similar to 8/28 by next Wednesday. Into the long range, a long wave trough in the jet stream is modelled to form in the austral mid latitudes and hold 8/28-9/2. At the surface, storm-force systems are at the eastern edge of the Hawaii swell window, with a wide area of 30-40 feet seas aimed best at the Americas. A series of surface low pressure areas are modelled to fill into the same area. Angular spreading should make for a long-lived spell of long-period surf locally, with peak days potentially above average within 9/4-8 from 180-200 degrees. Long-period surf from Jimena is suggested to be long-lived, keeping eastern exposures above average 9/2-7. Ignacio and Kilo will be monitored for surf within W to NNW 9/3-7. Long range forecasts are subject to low confidence. This collaborative forecast will resume on Monday, August 31. This forecast was produced through the collaborative efforts of NWS and NCDDC. Please send suggestions to w-hfo.webmaster@noaa.gov or call the Warning Coordination Meteorologist at 808-973-5275. Additional resources: see /in lowercase/ http://www.prh.noaa.gov/hnl/pages/marine.php.
Collaborative Surf Table
FORECAST
DATE
SWL
HGT
DMNT
DIR
DMNT
PD
H
1/3
H
1/10
HGT
TEND

PROB
WIND
SPD
WIND
DIR
SPD
TEND
1PM
08/28
4WNW19810UP7-10EUP
3NNE813UP
2SSE1224DOWN
2SSW1535UP
2WSW1013SAME
SAT
08/29
4WNW17610DOWNHIGH9-13EUP
3NNE813SAMEMED
2SSW1424DOWNMED
2WSW1013SAMELOW
SUN
08/30
3WNW1447DOWNLOW11-16NEUP
3NNE813SAMELOW
5ENE724UPLOW
2S1324SAMELOW
2WSW1024SAMELOW
MON
08/31
2WNW1224DOWNLOW17-21NNEUP
3NNE1024UPLOW
7NE735UPLOW
5ESE14610UPLOW
2S1324SAMELOW
TUE
09/01
9NNE868UPLOW22-27NUP
8E141015UPLOW
2W1424UPLOW
WED
09/02
8N12812DOWNLOW11-16WNWDOWN
5ESE171012UPLOW
2SSW1635UPLOW
2W1424UPLOW
Disclaimer
SURF HEIGHTS WILL VARY BETWEEN DIFFERENT BEACHES AND AT THE SAME BEACH AT DIFFERENT BREAK AREAS.
Collaborative Surf Table Legend

LEGEND:

SWL HGTOPEN OCEAN SWELL HEIGHT MEASURED FROM TROUGH TO CRESTIN FEET LOCATED 20 NAUTICAL MILES OFFSHORE
DMNT DIRDOMINANT DIRECTION TYPICALLY +/-10 DEGREES IN 16 COMPASSPOINTS
DMNT PDDOMINANT PERIOD IN SECONDS
H1/3SIGNIFICANT WAVE HEIGHT IN THE SURF ZONE
H1/10AVERAGE HEIGHT OF THE HIGHEST ONE-TENTH WAVES IN THE SURFZONE
HGT TENDHEIGHT TENDENCY OF SWELL (VALID VALUES: UP/DOWN/SAME)
PROBPROBABILITY OF OCCURRENCE (VALID VALUES: HIGH/MED/LOW)
WIND SPDOPEN WATER WIND SPEED MEASURED IN KNOTS LOCATED20 NAUTICAL MILES OFFSHORE
WIND DIRWIND DIRECTION IN 16 COMPASS POINTS
SPD TENDWIND SPEED TENDENCY (VALID VALUES: UP/DOWN/SAME)
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NWS FORECASTER AND NCDDC PAT CALDWELL

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