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SURF ZONE FORECAST
NATIONAL WEATHER SERVICE HONOLULU HI
300 PM HST SUN FEB 17 2013
OAHU-
300 PM HST SUN FEB 17 2013
HIGH SURF ADVISORY FOR NORTH, WEST AND EAST FACING SHORES
Surf along north facing shores will be 18 to 24 ft, lowering to 12 to 18 ft Monday.
Surf along west facing shores will be 12 to 18 ft, subsiding to 8 to 12 ft Monday.
Surf along east facing shores will be 7 to 10 ft with occasional higher sets through Monday.
Surf along south facing shores will be flat to 2 ft through Monday.
Outlook through Saturday Feb 23: the current northwest swell will peak tonight followed by a gradual lowering through Monday. A moderate size northwest swell will arrive Wednesday night, peaking Thursday night. Surf from this swell is expected to stay below advisory levels. Meanwhile, the east facing shores will continue to be affected by an above normal very choppy and rough trade wind swell through most of the forecast period.
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 FRI FEB 15 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 02/15 | 9 | NNW | 15 | 16 | 22 | UP | 17-21 | E | UP | |
| 7 | ENE | 7 | 3 | 5 | UP | |||||
| SAT 02/16 | 6 | NNW | 14 | 10 | 12 | DOWN | HIGH | 22-27 | E | UP |
| 9 | E | 7 | 4 | 6 | UP | MED | ||||
| SUN 02/17 | 9 | WNW | 20 | 20 | 26 | UP | HIGH | 22-27 | E | SAME |
| 10 | E | 8 | 6 | 8 | UP | MED | ||||
| MON 02/18 | 7 | NW | 15 | 12 | 16 | DOWN | MED | 22-27 | E | SAME |
| 11 | E | 9 | 7 | 10 | UP | LOW | ||||
| TUE 02/19 | 3 | NW | 13 | 4 | 6 | DOWN | LOW | 22-27 | E | SAME |
| 11 | E | 10 | 8 | 12 | SAME | LOW | ||||
| WED 02/20 | 2 | NNW | 20 | 4 | 6 | UP | LOW | 22-27 | E | SAME |
| 11 | E | 10 | 8 | 12 | SAME | 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 through the weekend from the northwest with easterly windswell steadily building into Tuesday.
Detailed: mid Friday on northern shores has high to marginally extra-large breakers, meaning surf on select outer reefs, from 290-335 degrees, though mostly focused on 325 degrees. Heights should drop on Saturday.
A complex pattern of low pressure approached the dateline on Tuesday 2/12. Gales to severe gales during the initial stages over the 290-315 degree band are making for the more westerly component on Friday 2/15. A secondary fetch of storm-force winds formed 2/12 further north over the 315-330 degree band. This fetch lengthened into Wednesday 2/13 with the fetch head about 1000 nm away from Hawaii. Highest seas were aimed at targets NE of Hawaii. Seas aimed towards Hawaii were within 20-25 feet. The system moved out of the Hawaii swell window Wednesday night.
Buoy 51101 NW of Kauai showed a sharp rise late Thursday. This buoy suggests the peak of the episode on Oahu between 3-7 pm, Friday 2/15. The episode is expected to drop off steadily in the wee hours Saturday, with upper-end moderate to occasionally near high breakers at dawn 2/16. Heights should hold in the moderate bracket through Saturday focused on 325 degrees though spread from 290-345 degrees.
A hurricane-force low pressure formed late Tuesday NE of Tokyo. It had a fairly straight east track along 40°N, reaching its occlusion point on Wednesday near 165°E. The track allowed a captured fetch, meaning waves travelling towards Hawaii were moving at about the same speed as the center of low pressure, allowing a longer apparent fetch in time and duration over the 300-310 degree band. The jason altimeter validated the Wave Watch III model of seas over 35 feet on Thursday. By Friday 2/15, the center of low pressure is beginning to fill, meaning rising pressures and a weakening system. It is expected to fade out over the eastern Aleutians on Saturday. The source for this episode was generated beyond 2000 nm, with travel distance allowing significant swell decay.
Long-period forerunners are due locally late afternoon Saturday with 23-27 second intervals, though of magnitude lower than the decaying NNW episode. Heights should grow into high levels overnight Saturday night from 300-310 degrees. Heights should reach extra-large on Sunday, with the episode peaking late afternoon. Neap tides should limit coastal wave wash to neglible levels. Surf should drop to marginally high levels by dawn on Monday from 300-315 degrees, then to moderate heights by Monday afternoon. Small surf could linger on Tuesday.
Models show a hurricane-force system forming east of Japan on Saturday. It could have long-period forerunners from 300-315 degrees late Wednesday 2/20.
Mid Friday on eastern shores has small breakers. Heights should increase on Saturday.
The jet stream pattern is favoring a ridge east of the dateline over the next week, with a series of troughs from west of the dateline being de-amplified and forced along the top side of the ridge near the Aleutians. These features are space a few days apart. At the surface, a series of strong, broad high pressure cells are modelled to follow each of those jet trough features, with the net result being continued reinforcement of above average trades for a wide longitudinal band within roughly 140-170°W. Strong trades over and upstream out over 800 nm to the east from Hawaii should make for a steady rise in the dominant wave period of the windswell, leading to growth in the size of breakers, since longer waves amplify more upon shoaling. Moderate surf is expected by Saturday 2/16, reaching marginally high levels on Sunday 2/17, and holding above average Monday through Wednesday 2/18-20. Surface conditions should remain rough through the period.
Mid Friday on southern shores has flat to tiny surf. Similar surf is expected on Saturday.
The easterly windswell described above should affect select southern and northern shores through the period.
Into the long range, marginal gales SE of New Zealand have formed and are expected to continue off and on within 2/13-19. The magnitude of the ocean surface winds are too weak to make more than small surf locally. Tiny to small, long-period surf from 180-200 is possible locally 2/21-25 with subtle ups and downs.
In the northern hemisphere, the hurricane-force system in the models for 2/16 is expected to have an occlusion point further west, keeping the fetch beyond 2400 nm from Hawaii. The system is predicted to be broad and long-lived 2/16-18. The long travel distance means only a moderate episode is expected, building Wednesday night, peaking Thursday 2/21 from 300-320 degrees, then slowly dropping into 2/23.
Above average easterly windswell under fresh to strong trades are expected to continue 2/21-23.
Long range forecasts are subject to low confidence.
This collaborative forecast will resume on Tuesday, February 19.
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
