HIGH SURF WARNING FOR NORTH AND EAST FACING SHORES
Surf along north facing shores will be 10 to 14 feet this morning. Surf will rise rapidly to 20 to 30 feet during the afternoon and early evening, then remain 20 to 30 feet through Thanksgiving Day.
Surf along west facing shores will be 2 to 4 feet this morning, rising to 3 to 5 feet this afternoon through Thanksgiving Day.
Surf along east facing shores will be 5 to 8 feet this morning. Surf will rise to 10 to 15 feet during the afternoon and early evening, then remain 10 to 15 feet through Thanksgiving Day.
Surf along south facing shores will be 1 to 3 feet through Thanksgiving Day.
Outlook through Wednesday November 29: A large north swell is expected to build rapidly during the afternoon and evening, peak late tonight into Thanksgiving Day, then decline Thursday night and Friday. A High Surf Warning has been issued for north and east facing shores through Thursday night. Trade winds will also become strong across the island chain beginning this afternoon and evening, and continuing through the weekend, resulting in rough conditions along east facing shores. A series of small but long period south swells will prevent surf from going flat along the south facing shores through the weekend. Another large north swell may arrive Sunday and continue into early 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, 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 Table
Collaborative Surf Table Legend
|SWL HGT||Open ocean swell height measured from trough to crestin feet located 20 nautical miles offshore|
|DMNT DIR||Dominant direction typically +/-10 degrees in 16 compasspoints|
|DMNT PD||Dominant period in seconds|
|H1/3||Significant wave height in the surf zone|
|H1/10||Average height in the highest one-tenth waves in the surfzone|
|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 located20 nautical miles offshore|
|WIND DIR||Wind direction in 16 compass points|
|SPD TEND||Wind speed tendency (valid values: UP/DOWN/SAME)|
Surf heights will vary between different beaches and at the same beach at different break areas.
Collaborative Surf Discussion
DISCUSSION: SUMMARY:. Steady N to NE above-average surf.
DETAILED:. Mid Wednesday on has breakers above the Fall average from 355-030 degrees. An sharp increase is expected late Wednesday.
The north Pacific jet stream has maintained a blocking ridge near the Date Line over the Aleutians and troughs or cut-off lows in the Gulf of Alaska for a few weeks. This has kept dominant N to NNE surf for most of November.
The next rise in surf is due late Wednesday 11/22. It is expected to rapidly build to extra-large levels, meaning high enough to break on outer reefs. With this magnitude, refraction and diffraction into western and eastern facing shores is expected during the larger portions of the event.
It was generated by a storm-force low pressure system that dug SSE from SW of Anchorage, Alaska, 11/19 setting up a captured fetch over the 000-020 degree band. As the fetch stretched southward, the wind speeds slowly decreased with severe gales to near 45N and gales to 35N by 11/21. Models show the low weakening 11/22 it moves towards the west coast of the USA.
The JASON altimeter validated well the Wave Watch III model output for the seas of 20-25 feet in the region 35-45N to the NNE of Hawaii. Even when the wave model validates well at the remote source, the model tends to bias low for the output point at the Waimea buoy; hence the numbers above are nudged up a notch or two.
Long-period swell of 14-17 seconds is slowly climbing mid to late morning 11/22 at the NOAA NW Hawaii buoys and the PacIOOS Hanalei buoy. It should climb into extra-large levels on Oahu within sundown to midnight 11/22 from 355-020 degrees.
Short- to moderate-period wave energy from 000-030 degrees generated by near gales that nosed to 30N on 11/21 and increasing strong breezes to 23N 11/22, respectively, both N to NNE of Hawaii, should also arrive on Thursday, making for disorganized breakers.
Extra-large surf conditions are expected to hold into Friday morning with a downward trend to near average by mid Saturday, and below average late Saturday. By early Sunday, forerunners from a new N event are due to arrive.
Models show a new storm-force system tracking SSE from the eastern Aleutians early Thursday 11/23. It is expected to occlude in the Gulf of Alaska and keep a nearly stationary surface low pressure to severe gale strength through Friday, slowly weaken to gale Saturday, then lift out to the east on Sunday. It should make for a long-lived surf event locally.
The surf should build Sunday morning from 000-020 degrees, reaching the Fall average by Sunday afternoon, peak morning, and remain above average through Monday from the same direction.
Mid Wednesday on has above average breakers for more northerly exposures. The longer period N to NNE swell should keep active breakers through the period with trends aforementioned.
See the latest NWS State Forecast Discussion for an explanation of the weather features affecting the local winds and weather through the period.
The local windswell is expected to veer on the compass through the period with more NNE direction 11/22 into 23, NE 11/23-24, NE to ENE 11/24-25, and ENE to E 11/26-27. Rough breakers at levels above the trade windswell average are expected through the period.
Mid Wednesday on has mostly flat conditions with tiny to small breakers at zones of high refraction. Similar conditions are predicted 11/23-24.
A severe-gale grew seas to 25 feet as a system tracked east along 60S to the SE of New Zealand 11/17-19. Angular spreading could bring in low, long-period swell from 180-190 degrees making for small breakers at high refraction zones late Saturday into Monday. Most areas should remain flat to tiny.
, back to seasonal near nil for southern hemisphere swell 11/28-30 with dominant breakers refracting E windswell with size depending on exposure.
In the north Pacific, the long-lived Date Line jet stream block is predicted to give way to a zonal pattern embedded with fast- moving short-wave troughs. At the surface, gales to storm-force systems are modelled to track east just south of the Aleutians with about a 2-3 day spacing. The first one is predicted to intensify near the Date Line Saturday night and bring an above average NNW event filling in late 11/28 and peaking 11/29. The second one is suggested to be larger and fill in 11/30, peaking 12/1, also mostly NNW.
Easterly windswell should remain near or above average from 60-90 degrees within 11/28-30.
Long range forecasts are subject to low confidence.
This collaborative forecast will resume on Friday, November 24.
This forecast was produced through the collaborative efforts of NWS and NCEI. Please send suggestions to firstname.lastname@example.org or call the Warning Coordination Meteorologist at 808-973-5275.
ADDITIONAL RESOURCES: See http://www.prh.noaa.gov/hnl/pages/marine.php
NWS Forecaster and NCEI Pat Caldwell