Surf Report for Hawaii
Surf along north facing shores will be 3 to 5 feet today, lowering to 1 to 3 feet Friday.
Surf along east facing shores will be 2 to 4 feet through Friday.
Surf along south facing shores will be 2 to 4 feet today, rising to 3 to 5 feet Friday.
Surf along west facing shores will be 2 to 3 feet through 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.
The SRFHFO product will change format and be expanded to more islands on or about September 10, 2020. More information at: https://www.weather.gov/hfo/statesurf2020 .
|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)|
DISCUSSION: SUMMARY.... Abundant high season surf.
DETAILED:. Mid Wednesday on northern shores has well above seasonal average breakers of 14-22 seconds from 300-330 degrees. This event is predicted to remain well above average Thursday though with a downward trend from the same direction.
A hurricane-force system tracked east from the far NW Pacific maintaining strength to the Date Line 11/28-29. The system occluded near 50N, 165W 11/30 with top winds near storm-force. This is the source for the surf arriving locally 12/2. The long path of the source placed energy over a wide wave directional spread for Hawaii.
The longest fetch was within 300-320 degrees and allowed the dominant wave periods to increase to within 20-25 seconds. These extra-long swell trains passed under the NW Hawaii NOAA buoys 12/1. Interesting the difference between 51001 and 51101, which is just SW of the former, in spectral density, or wave energy, in the 19-23 second bands, with the former higher. This can be explained by partial shadowing by NW Hawaiian Islands on the latter. There was more WNW energy to this swell than predicted, with a 7 feet difference during peak swell height readings between 51001 and the PacIOOS/CDIP Waimea, Oahu buoy, which was subject to the Kauai shadow.
The Wave Watch III, WW3, handled the timing of the event reasonably well, but was lower in swell height for the Waimea output point compared to the buoy data. It is uncommon for the WW3 to bias high. WW3 did do well on the timing of the peak of the event, which was estimated near 4 AM 12/2, with Waimea buoy hitting a peak reading of 14 feet at 18 seconds. The Mokuoloe tide gauge in Kaneohe bay showed 3 feet water levels peaking at the same time. This allowed well above average wave runup. Being the first major event of the year, the existing sand serves as a buffer. Events later in the winter with less sand can have a greater landward reach for the same incident wave flux.
NW buoys midday 12/2 show ample energy in the 15-17 second band. The energy is shifting towards lower dominant wave periods and the magnitude of the energy is slowly lowering. But the event is far from over. Heights on Thursday should remain extra-large, defined when the surf size is high enough to trigger outer reefs. It should fall below extra-large to near December average levels on Friday, slowly decreasing into the afternoon as a new event overlaps.
A broad area of low pressure 12/1 set up a long, wide fetch of low-end gales from the Kuril Islands to east of the Date Line over the 300-320 degree band into 12/2. Models show the head of the fetch of near gales to reach about 700 nm from Oahu l2/2 PM. This closer source should supplement the surf Friday putting an upward trend from 300-320 degrees mid to late afternoon. Heights should hold about the same Saturday morning with wave periods of 10-14 seconds.
Models show the broad area of low pressure aforementioned to occlude 12/3 near 50N, 170W with about a day of gales over the 315-325 degree band nosing to near 1000 nm away early Friday 12/4. Proximity should allow above average surf to build Saturday midmorning with 14-16 second periods from 315-330 degrees. It should peak overnight and slowly drop on Sunday while remaining above average from the same direction.
Yet another winter-caliber low-pressure system is in the prognostics starting 12/4. Models show a system bombing, which means the central pressure drops sharply over a short time interval of about a half day, as it approaches the Date Line at 45N Friday PM. The system is modelled to occlude near 50N, 165W Saturday 12/5 of central pressure near 950 mb. The broad cyclonic gyre should move slowly 12/5-6 and make for a long-lived swell event for Hawaii.
Forerunners are due near sundown Sunday from 300-320 degrees. It should rise rapidly Sunday night to extra-large levels. The peak of the event is suggested for pre-dawn Monday from 310-330 degrees holding about the same through the day.
Mid Wednesday on eastern shores has below average breakers from the trade wind belt of 60-90 degrees. Trade wind swell should remain near nil on Thursday. The large NW event aforementioned is affecting select east side locations 12/2 and should trend down 12/3.
See the latest NWS State Forecast Discussion regarding the trend in local winds and skies.
A short-lived trade wind event is modelled to pick locally late Thursday and peak Friday PM with local winds similar to last Friday PM. The upstream fetch is predicted to be short, so minimal breakers from wind swell are expected, which should have small levels late Friday into Saturday from 40-70 degrees.
Mid Wednesday on southern shores has near nil breakers typical of late fall. Similar surf is predicted for Thursday
No austral midlatitude sources in the Hawaii south swell window were identified last week that could bring surf much beyond the December average of near nil midweek into early next week.
Into the long range, a storm-force low pressure system tracked steadily east SW to S of New Zealand 12/1-2. Seas were 30-40 feet. Models show winds mostly west to east with a weakening trend as the source moves SE of New Zealand 12/2-3 in the favorable Hawaii swell window. Out-of-season, low, long-period surf from 190-220 degrees is possible locally within 12/8-12 with peak days near the summer average.
NW to N exposures should remain extra-large Tuesday 12/8 with a downward trend to near December average levels by 12/9 from 315-340 degrees.
East side may slowly trend up from 60-90 degrees 12/8-9.
Long range forecasts are subject to low confidence.
The next Collaborative Forecast will be updated Friday, December 4.
This forecast was produced through the collaborative efforts of NWS and NCEI. Please send suggestions to email@example.com or call the Warning Coordination Meteorologist at 808-973-5275.
ADDITIONAL RESOURCES: See https://www.weather.gov/hfo/marine