SURF ZONE FORECAST
NATIONAL WEATHER SERVICE HONOLULU HI
340 PM HST FRI JAN 20 2017
340 PM HST FRI JAN 20 2017
HIGH SURF ADVISORY FOR NORTH AND WEST FACING SHORES THROUGH
EARLY SATURDAY MORNING
HIGH SURF ADVISORY FOR EAST FACING SHORES STARTING NOON
Surf along north facing shores will be 10 to 15 feet tonight, lowering to 8 to 12 feet Saturday.
Surf along west facing shores will be 8 to 12 feet tonight, lowering to 4 to 8 feet Saturday.
Surf along east facing shores will be 2 to 4 feet tonight, rising to 6 to 10 feet Saturday.
Surf along south facing shores will be 2 to 3 feet through Saturday.
Outlook through Friday January 27: the current northwest swell will lower gradually over the weekend. Strengthening northeast winds behind a cold front this weekend will produce large, choppy surf along east facing shores Saturday through Monday. Surf will remain generally small along south facing shores, but a small bump is possible for Sunday. A new large northwest swell arriving Monday may build near the high surf warning threshold by Wednesday.
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 SWELL AND WIND FORECAST FOR OAHU
NWS/NCDDC HONOLULU HI
303 PM HST THU JAN 19 2017
THIS COLLABORATIVE FORECAST WILL BE UPDATED MONDAY THROUGH FRIDAY AT
300 PM WHEN PAT CALDWELL IS AVAILABLE/
|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 OF 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.
Discussion: summary: North Pacific surf from W to N to E.
Detailed: Mid Thursday on northern shores has slowly declining breakers from 280-330 degrees at levels above the active season, September to may, average. A new source is expected to overlap this declining event, keeping breakers above average on Friday.
North Pacific wave sources are in winter mode with active wave generation from east of Japan to the gulf of Alaska, giving overlapping events and wide spans in wave directions for Hawaii.
For the WNW component swell, a series of sources west of the dateline have kept active surf locally. The surf arriving 1/19 was generated 1/14-16 associated with a low center that tracked from near Japan to north of Hawaii by 1/17. The pacioos/cdip buoy off SW Oahu shows active swell from 280-305 degrees. This first source should continue on Friday as a reinforcement arrives.
The next low pressure in the series added energy to the 280-305 degree band 1/16-17 west of the dateline. It was weaker, but could keep small breakers from this directional band late Friday into Saturday.
The WNW energy should fade out for Sunday into Monday. An increase is expected for Tuesday.
For the NW to NNW energy, a steady supply is expected through the period with a minimum Sunday into Monday. The low that passed north of Hawaii 1/17 had seas to 35 feet aimed at targets NE of Hawaii. Surf from this source is arriving 1/19 from 305-330 degrees. These near miss to the NE events have larger error bars. This event came in higher than expected in the morning 1/19. It should trend down into Friday morning as a new event builds.
The next low gained steam as it crossed the dateline 1/18 and is passing north of Hawaii 1/19. It reached storm-force strength on 1/18 to the NNW of Hawaii. Like the previous system, surface ocean winds were mostly west to east south of the low, aiming highest seas NE of Hawaii. This give the same issue of near miss to the NE. Surf from this system should build locally Friday morning, peak Friday evening at levels above average, and drop to near average early Saturday from 305-330 degrees.
A strong high pressure center is modelled to track east from the dateline Friday, following a front, which is expected to push through Oahu Saturday. A large, long fetch of strong to marginal gales to the NNW to N of Hawaii 1/20-21 should make a rough windswell from 330-010 degree building Saturday. It should peak from this direction Saturday night, then slowly decline Sunday into Monday as the direction favors 350-030 degrees.
Models show a winter-caliber low pressure system forming off Japan Friday night, reaching the dateline Sunday as it occludes just south of the Aleutians. In the initial 48 hours, severe- gales to storm- force winds are expected over the 280-305 degree band, reaching to near 1500 nm away. Long-period swell from this direction should build on Tuesday 1/24 and hold into 1/25.
As the system occludes on Sunday, the low center is predicted to dip to 952 mb and slowly move east just south of the Aleutians east of the dateline. This will add severe gale to hurricane-force winds over the 305-330 degree band of a long, wide fetch mid Sunday to Monday night, with the head of the fetch reaching within 1000 nm away late Monday.
Proximity should make the NW to NNW component larger for Hawaii. It should build rapidly Tuesday from 305-330 degrees to extra- large levels, meaning breakers on outer reefs. It is predicted to peak Tuesday night and remain extra-large on Wednesday.
Mid Thursday on eastern shores has breakers below the trade windswell average. Heights should remain low on Friday.
See the latest NWS state forecast discussion for timing on the frontal passage and associated wind and weather 1/21.
The rough NNW to NNE windswell Saturday should be high enough magnitude to refract into more easterly exposures at the same time the local wind veers on the compass from N to NE. Thus windswell from 20-60 degrees should build Saturday as well. For Sunday, the mix from N to E should make for rough, above average breakers, remaining above average into Monday as the dominant wave direction veers east. Surf should drop near to below average by Tuesday from 50-90 degrees, though long-period NW swell should start to refract and diffract into most shores.
Mid Thursday on southern shores has nil energy from the southern hemisphere, yet refracting and diffracting WNW energy for select westerly exposures. More of the same is expected on Friday.
A storm-force system in the southern Tasman sea 1/14 could make for a low, long-period swell centered on Sunday 1/22 from 208-220 degrees.
Into the long range, active extratropical cyclones SE and SW of New Zealand could make for a few days above the winter nil locally for the tail end of January. It is too early for specifics.
In the northern hemisphere, above average NW to NNW surf should hold 1/25-26. Models suggest a low pressure broadening and deepening east of the dateline 1/26-28, that could bring above average NW to NNW surf for the weekend of 1/28-29.
Windswell from 50-90 degrees is expected to be below average 1/26-28.
Long range forecasts are subject to major revisions.
This collaborative forecast will resume on Monday, January 23.
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 /in lowercase/ http://www.prh.noaa.gov/hnl/pages/marine.php.
NWS Forecaster and NCEI PAT CALDWELL
|Waimea Buoy||Kailua Buoy||Lanai Buoy||Barbers Point #2||Pauwela, Maui||Hilo Bay Buoy||Kaneohe Bay Buoy||Hanalei Kauai Buoy||Kilo Nalu||Buoy 51001||Buoy 51101||Buoy 51000||Buoy 51100||Buoy 51002||Buoy 51003||Buoy 51004|