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FZHW52 PHFO 
SRFHFO
SURF ZONE FORECAST
NATIONAL WEATHER SERVICE HONOLULU HI
700 PM HST WED JAN 16 2013
OAHU-
700 PM HST WED JAN 16 2013
HIGH SURF ADVISORY FOR NORTH FACING SHORES
Surf along north facing shores will be 10 to 15 feet through Thursday, building to heights of 15 to 20 feet Thursday evening.
Surf along west facing shores will be 6 to 10 feet through Thursday, building to heights of 10 to 14 feet Thursday evening.
Surf along east facing shores will be 4 to 6 feet tonight, dropping to heights of 3 to 5 feet Thursday.
Surf along south facing shores will be 1 to 2 feet through Thursday.
Outlook through Tuesday Jan 22: a powerful long-period northwest swell will build starting Thursday afternoon, and will remain elevated through Sunday. As a result, expect surf heights to remain near the high surf warning criteria along north and west facing shores from late Thursday night through Sunday. Elsewhere, the easterly swell will continue to slowly diminish 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, 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
300 PM HST WED JAN 16 2013
This collaborative forecast will be updated Monday through Friday at 300 pm when Pat Caldwell is available.
| FORECAST DATE | SWL HGT | DMNT DIR | DMNT PD | H 1/3 | H 1/10 | HGT TEND | PROB | WIND SPD | WIND DIR | SPD TEND |
| 1PM 01/16 | 8 | NW | 13 | 14 | 18 | DOWN | 7-10 | NNW | SAME | |
| 4 | NNW | 9 | 4 | 6 | SAME | |||||
| 4 | ENE | 9 | 4 | 6 | DOWN | |||||
| THU 01/17 | 8 | NW | 13 | 14 | 18 | DOWN | MED | 7-10 | N | SAME |
| 4 | NNW | 9 | 4 | 6 | SAME | LOW | ||||
| 3 | ENE | 9 | 3 | 5 | DOWN | LOW | ||||
| 6 | WNW | 24 | 14 | 18 | UP | LOW | ||||
| FRI 01/18 | 5 | NW | 11 | 6 | 10 | DOWN | LOW | 9-13 | NNW | UP |
| 10 | WNW | 20 | 24 | 30 | UP | HIGH | ||||
| 3 | N | 10 | 4 | 6 | UP | LOW | ||||
| SAT 01/19 | 11 | NW | 17 | 24 | 30 | SAME | HIGH | 11-16 | N | SAME |
| 4 | N | 9 | 4 | 6 | SAME | LOW | ||||
| SUN 01/20 | 9 | NW | 14 | 16 | 22 | DOWN | LOW | 11-16 | NNE | UP |
| 12 | NNW | 14 | 24 | 30 | UP | LOW | ||||
| 7 | NNE | 8 | 4 | 6 | UP | LOW | ||||
| MON 01/21 | 5 | NW | 13 | 8 | 10 | DOWN | LOW | 17-21 | NE | UP |
| 8 | N | 12 | 12 | 16 | DOWN | LOW | ||||
| 8 | NE | 9 | 6 | 8 | UP | LOW |
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) |
Compass & Swell Shadow Lines for Hawaii
SURF HEIGHTS WILL VARY BETWEEN DIFFERENT BEACHES AND AT THE SAME
BEACH AT DIFFERENT BREAK AREAS.
DISCUSSION:
Summary: active surf pattern for north shores from remote and nearby sources.
Detailed: mid Wednesday on northern shores has moderate to marginally high surf from 305-325 degrees with 10-16 second intervals. Similar surf is likely into Thursday morning with a new extra-long wave period, WNW episode rising in the afternoon.
A broad trough in the jet stream slowly moved east from the dateline 1/11-14. The axis is slightly east of the longitude of Oahu on 1/16. Models show several short-wave reinforcements spaced about a day apart filling into and reinforcing the trough 1/17-19, as the axis finally pushes east and pinches off an upper level gyre near 140°W this weekend. At the surface, there have been numerous individual low pressure cells spaced about a day apart mostly within 30-40°N, 170°E to 160°W, making for overlapping surf episodes locally as a mix of moderate wave period, 13-15 seconds, and shorter-period, 9-12 second energy. This general pattern will be a surf producer through Monday.
The surf on Wednesday 1/16 has dominant energy of 13-16 seconds from gales just west of the dateline Saturday 1/12. Buoy 51101 WNW of Kauai shows a downward trend in the 13-16 second energy on the morning of 1/16. This suggests local surf trending down for the afternoon 1/16. However, another pair of complex lows passed the dateline on Monday. Wave watch iii, ww3, model output shows this reinforcement keeping the surf about the same, so there could be just enough uptick in wave energy early Thursday to keep marginally high breakers into mid day from 305-320 degrees.
A pair of weak low pressures and associated weak fronts between 25-40°N latitude N to NNE of Hawaii on 1/15-16 is expected to keep small shorter-period surf from within 340-010 degrees Thursday into Friday.
Further west, a low pressure bombed, or dropped radically in central surface pressure, 1/14-15. The center of the low tracked exceptionally fast from near Tokyo Monday morning to 40°N, 160°E late Monday, where the system became occluded. This means the upper level and lower level gyres become stacked, making the surface low center stalls in track speed. The moment of occlusion coincides with the deepest surface pressure, which dropped to 932 mb for this system at 06Z 1/15. The early stages of occlusion also are near the time of the peak surface wind speeds.
Backing up to the genesis of the system, hurricane-force winds formed early Monday near Japan over the 285-300 degree band relative to Hawaii. The fast forward track across the great circle rays to Hawaii limit surf potential from this directional band.
The hurricane-force winds covered a large area to the S to SW of the low center aimed towards Hawaii over the 295-310 degree band Monday afternoon into Tuesday. Ww3 estimated seas well over 40'. A jason satellite overpass 06Z 1/15 showed seas aimed towards Hawaii that were near to slightly under the ww3 estimate. The head of the fetch was near 2000 nm away from Hawaii. Extreme winds over large areas for sufficient time grow extra-long wave periods to around 25 seconds, which travel near 900 nm a day. Ww3 model output for Waimea buoy shows forerunners of 25-28 seconds Thursday morning 1/17. Since the energy would be focused in a narrow wave period band, sets are likely to be inconsistent. Ww3 shows higher swell with 22-25 seconds building locally Thursday afternoon. Long wave periods have greater amplification while breaking, so the moderate size swell heights at extra-long wave periods spells high surf locally Thursday afternoon. The Kauai shadow effect will cause a gradient in wave energy along the coast increasing towards the north.
Surf from 295-310 degrees should climb into extra-large heights Thursday night and hold through the day Friday. Heights in the table above refer to zones of high refraction, which focus on outer reefs during extra-large conditions. Near shore heights are lower.
On Tuesday into Wednesday, the occluded surface low center jogged slightly to the NNE, with a long, wide, nearly stationary fetch of severe gales to hurricane-force winds stretching nearly 800 nm long and 500 nm wide over the 305-320 degree band. There was a slow weakening of surface wind speeds Tuesday night into Wednesday 1/15-16. Another jason overpass 06Z 1/16 was also near to just under the ww3 model estimate of sea heights. Since both jason passes did not surpass ww3, this forecast is assuming Waimea buoy should see the same or slightly less significant swell heights as estimated by wave model.
Surf on Saturday should remain extra-large with more directional pinch from straight NW, reducing the Kauai shadow factor. The remote distance should mean the higher sets are less frequent than closer sources.
The remote source is expected to maintain gales over a large area with a westward drift to the head of the fetch mid Wednesday into Thursday. This should keep high surf locally from 305-320 degrees on Sunday, with a slow downward trend to Tuesday. However, several other sources are predicted to make local surf Sunday through Tuesday.
As introduced at the start of this discussion, a broad jet stream trough north of Hawaii has been affecting local waves. Models show the axis of the jet trough moving east Friday into Sunday. At the surface, a gale low pressure is modelled to form near 40°N 175°W early Friday 1/18, with a track to the ESE. Gales would be working on existing swell from the previous systems, so a rapid rise in sea heights is expected. The captured fetch is modelled to generate high swell with a near miss for Hawaii. Ww3 is showing wave heights of 24 feet at the buoy 51000 position to the ENE of Oahu on late Saturday night. Surf on Oahu is expected to rise rapidly from 330-360 degrees Sunday morning. Combined with the remote source, extra-large breakers are predicted to continue on Sunday with more north pinch.
The proximity of the reinforcement episode should lead to a rapid rise as well as decline. Surf heights are modelled to drop below the extra-large bracket by Monday morning, with moderate to marginally high conditions from 310-000 degrees through the day Monday.
Mid Wednesday on eastern shores has moderate breakers. The long-lived east swell is expected to drop to within small to moderate on Thursday, and fade out on Friday.
See the latest NWS state weather forecast discussion for the freshest outlook and explanation for local winds and weather 1/17-21. Winds north of a front that is due locally Friday night is expected to deliver a moderate NNW to NNE windswell, with mean direction 330-360 on Saturday, and veering to 360-030 degrees Sunday into Monday. Surf could increase to near high levels on Monday. Stay tuned for updates.
Mid Wednesday on southern shores has tiny to small breakers for select spots with a mix of refracting easterly and westerly swell. No surf from the southern hemisphere is expected through the period and into the long range 1/22-25.
Into the long range, models show a zonal jet stream pattern forming over the central north Pacific 1/18. A series of low pressures are modelled to cross the dateline 1/19-22. The should give surf locally peaking within moderate to marginally high levels. The first in the series, spaced 1-2 days apart, is due Tuesday 1/22 from 315 degrees.
Models suggest fresh trades locally 1/22-24, with enhanced trades near 130-140°W, 20-30 N due to a surface low pressure in the subtropics, that could make for high surf from within 30-90 degrees 1/22-25.
Long range forecasts are subject to major revisions.
This collaborative forecast will resume on Friday, January 18.
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.
NWS Forecaster and Pat Caldwell, Pacific/Hawaii Liaison Office, NCDDC
Additional Resources:
| Waimea Buoy | Kailua Buoy | Lanai Buoy | Barbers Point #2 | Pauwela, Maui | Kilo Nalu | Buoy 51001 | Buoy 51101 | Buoy 51000 | Buoy 51100 | Buoy 51002 | Buoy 51003 | Buoy 51004 |
Latest North Pacific Surface Analysis
