Outlook through Thursday December 25: a large northwest swell arriving early Sunday will produce warning level surf Sunday and Monday along north and west facing shores. The surf will gradually diminish Tuesday through Thursday as fresh to strong north to northeast winds likely develop. In addition, a small boost in surf along south facing shores is possible over the next few 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.
No high surf advisory or warnings.
Surf along north facing shores will be 10 to 12 feet through the evening, dropping to 6 to 10 feet tonight, and lowering to 4 to 7 feet Saturday. Surf along west facing shores will be 6 to 8 feet through the evening, dropping to 4 to 6 feet tonight, and lowering to 2 to 4 feet Saturday. Surf along east facing shores will be 3 to 5 feet through tonight, lowering to 2 to 4 feet Saturday. Surf along south facing shores will be 1 to 3 feet tonight, rising to 2 to 4 feet Saturday.
About Collaborative Surf
This collaborative forecast will be updated Monday through Friday at 300 pm when Pat Caldwell is available.
Collaborative Surf Discussion
SURF HEIGHTS WILL VARY BETWEEN DIFFERENT BEACHES AND AT THE SAME BEACH AT DIFFERENT BREAK AREAS. DISCUSSION: Summary: mix of surf from sources in the northern and southern hemispheres. Detailed: mid Friday on northern shores has surf above the seasonal average from 305-330 degrees. Heights are expected to drop below average on Saturday from a similar direction. A gale system formed east of Japan 12/14 tracking east. A fetch over the 300-315 degree band nosed to about 1500 nm away by late Monday. Surf near to below the seasonal average from this directional band is arriving on Friday 12/19 with 13-15 second periods. This WNW directional swath should see a downward trend into Saturday. The same weather pattern gave NW to NNW swell of larger size. The weather system gained hurricane force as it crossed the dateline early Tuesday 12/16. The fast-moving track across the great circle rays relative to Hawaii limited generation of the longest wave periods. Hence the slow start to the episode on Thursday with the longest wave periods 17-19 second lower than modelled. The wave energy in the 13-16 second band from 315-330 degrees was dominant at the source, filled in locally Thursday night and peaked near sundown Friday. It is holding above average through the day 12/19 as the dominant direction off Oahu. Noaa buoy 51101 late morning 12/19 shows a steady downward trend to this event, which is expected to be short lived. It should steadily fall overnight to below seasonal average on Saturday from 300-330 degrees. A winter caliber pattern developed near Japan on Tuesday 12/16. A massive low pressure system slowly tracked east with severe gale to storm-force winds over a wide swath from 285-310 degrees. The head of the fetch reached 2000 nm away with seas near 40 feet by mid Thursday. Models show the wave generation over this WNW swath to end on Friday with the head of the fetch about 1200 nm away near the dateline. Error bars on the local surf estimates are higher for this directional band due to the shadowing of Kauai on Oahu. Long period WNW swell from this source is due to fill in overnight Saturday night, with surf heights climbing above average by dawn. Heights should continue to climb into the afternoon to extra-large levels, meaning breakers on outer reefs. Surf from 285-310 should peak Sunday night and slowly decline into Tuesday. Additional long-period surf is expected from NW to NNW from this weather pattern by Monday, though accompanied with choppy short-period N breakers making for rough conditions. The massive low pressure gyre fills a large portion of the north central Pacific north of 30°N on 12/19. Models show the system continuing an eastward track though slowing in pace, which will keep a long-lived fetch over the 310-345 degree band nosing to within 1000 nm of Hawaii late Friday into Sunday. This source should turn the dominant direction to within 310-325 degrees by Monday. The extra-large event should remain elevated through Monday night, and remain above average as it declines on Tuesday from a wide directional swath of 285-360 degrees. Heights should fall to near the seasonal average on Wednesday 12/24. Mid Friday on eastern shores has moderate to fresh trades from 70-90 degrees with breakers from windswell near the trade windswell average. Heights should slowly decline on Saturday. A high pressure cell near 30°N, 140°W 12/19 should keep at least near average trade windswell into Saturday, though falling below average by Sunday as the nearby winds weaken. See the latest NWS state forecast discussion regarding the timing of the changing weather and wind patterns going into early next week. Surf from 60-90 degrees should drop to tiny to small levels by Monday and remain low into Wednesday as dominant windswell favors northerly quadrants. High uncertainty remains on magnitude of the north-component winds following a front Monday into Tuesday. Model output made 12/19 suggests rough, above east-side average windswell from 000-040 degrees building Monday into Tuesday, and remaining elevated into Wednesday. Mid Friday on southern shores has tiny to small breakers at a few select spots. An increase is predicted for Saturday. A severe gale SE of New Zealand tracked east, aiming highest seas at targets SE of Hawaii 12/12-14. Long-period swell from this source is expected to fill in on Saturday with 16-18 second periods. It should peak on Sunday from 180-195 degrees near the summer south swell average. It is modelled to slowly decline Monday into Tuesday. Into the long range, this weather feature moved east of New Zealand 12/15 and stalled in a region about 3500 nm south of Hawaii. Marginal gales 12/15-18 have aimed best at targets SE of Hawaii, though it may be close enough to keep tiny to small breakers for select locations 12/24-26 from 170-180 degrees. In the northern hemisphere, short-period NNE to NE surf should continue into 12/25 with a fast downward trend 12/26. The next winter caliber low pressure is modelled to form near the Kuril Islands on Monday 12/22 with gales reaching to near 2000 nm away by 12/23 as it hits a block at the jet stream level. The long distance suggests a long-period WNW to NW swell near to below the seasonal average starting 12/27. Long range forecasts are subject to high uncertainty. This collaborative forecast will resume on Monday, December 22. This forecast was produced through the collaborative efforts of NWS and NCDDC. Please send suggestions to firstname.lastname@example.org 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
Collaborative Surf Table Legend
|SWL HGT||OPEN OCEAN SWELL HEIGHT MEASURED FROM TROUGH TO CREST IN FEET LOCATED 20 NAUTICAL MILES OFFSHORE|
|DMNT DIR||DOMINANT DIRECTION TYPICALLY +/-10 DEGREES IN 16 COMPASS POINTS|
|DMNT PD||DOMINANT PERIOD IN SECONDS|
|H1/3||SIGNIFICANT WAVE HEIGHT IN THE SURF ZONE|
|H1/10||AVERAGE HEIGHT OF THE HIGHEST ONE-TENTH WAVES IN THE SURF ZONE|
|HGT TEND||HEIGHT TENDENCY OF SWELL (VALID VALUES: UP/DOWN/SAME)|
|PROB||PROBABILITY OF OCCURRENCE (VALID VALUES: HIGH/MED/LOW)|
|WIND SPD||OPEN WATER WIND SPEED MEASURED IN KNOTS LOCATED 20 NAUTICAL MILES OFFSHORE|
|WIND DIR||WIND DIRECTION IN 16 COMPASS POINTS|
|SPD TEND||WIND SPEED TENDENCY (VALID VALUES: UP/DOWN/SAME)|
NWS FORECASTER AND NCDDC PAT CALDWELL