SURF ZONE FORECAST
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST FRI MAR 27 2015
400 AM HST FRI MAR 27 2015
Surf along north facing shores will be 5 to 7 feet today, lowering to 4 to 6 feet Saturday.
Surf along west facing shores will be 2 to 4 feet through Saturday.
Surf along east facing shores will be 5 to 7 feet through Saturday.
Surf along south facing shores will be 2 to 4 feet through Saturday.
Outlook through Thursday April 2: a moderate northwest swell is expected to fill in late Saturday night, peak late Sunday through Sunday night, then gradually subside through Tuesday. A trade wind swell will continue to impact the east facing shores through the weekend.
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 MAR 25 2015
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 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)|
SURF HEIGHTS WILL VARY BETWEEN DIFFERENT BEACHES AND AT THE SAME
BEACH AT DIFFERENT BREAK AREAS.
Summary: active surf from around the compass.
Detailed: mid Wednesday on northern shores has near flat conditions with rising, choppy N windswell. A new event is due overnight.
A low pressure deepened to the NNW of Hawaii Monday into Tuesday as it tracked steadily towards the gulf of Alaska. The weak low produced a broad area of fresh to near gale winds. The system strengthened as it passed the longitude of Hawaii, aiming highest seas to the NE of Hawaii. The head of the fetch reached to near 600 nm away on 3/24.
Shorter-period surf is predicted to build Wednesday night into Thursday from 325-345 degrees, reaching to near the seasonal average. It should drop below average before dawn Friday from 330-350 degrees. The tail of the fetch of strong to near gale breezes was 1600 nm away on 3/24-25, which should keep small, short-period breakers into Saturday from 330-360 degrees.
A new low pressure cell formed east of the Kuril Islands on 3/24. It has severe gales over the 295-305 degree band on 3/25. It is modelled to track east along 45°N, maintaining gale status 3/25-26. It is expected to weaken as it approaches the dateline mid Thursday then change track to the NE towards Alaska as it further decays on Friday.
Long-period forerunners from 295-310 degrees are due on Sunday morning, with breakers slowly building. Heights should steadily rise in the afternoon, reaching near the seasonal average near sundown. It should peak overnight Sunday night, then slowly decline on Monday from 300-320 degrees.
Mid Wednesday on eastern shores has near flat conditions. A new windswell is expected to build overnight for more N to NE exposures.
See the latest NWS state forecast discussion regarding an explanation for the evolving winds into the weekend.
Fresh trades are expected to veer on the compass Thursday into Friday with more northerly-component windswell from 20-50 degrees on Thursday, changing to 40-70 degrees on Friday. Heights should reach near the trade windswell average by mid Thursday, peak on Friday, and drop on Saturday.
Mid Wednesday on southern shores has surf above the summer average from 180-200 degrees with 13-16 second intervals. Heights are expected to lower on Thursday.
The extra-tropical remnant of cyclone Pam is expected to make for a long-lived event keeping surf through the period. The direction should favor the SSE starting Friday.
Pam became a cold-core, mid-latitude low pressure system by 3/16 just east of New Zealand with a slow weakening as it tracked east 3/17-18. Surf came in locally bigger than expected on 3/24 with the pacioos/cdip barbers PT buoy registering 3-4 feet deep water swell with 16-18 second periods. Looking back at the pacioos/cdip american samoa buoy from 3/20-21, the dominant periods were 14-16 seconds. As waves travel, the dominant period increases, which gave the longer periods locally. The longer the period, the greater the amplification when the swell shoals and refracts into breakers.
Dominant periods have declined on Wednesday, along with the surf size. Noaa buoy 51002 is operating once again and with a directional sensor. The peak of the episode has passed, though steady moderate-period swell of 13-15 seconds is holding on 3/25. Remote source swell change slowly since the energy is spread over wide areas. This should mean just a notch down for Thursday. The energy from 180-200 degrees should fall to small levels Friday and fade out on the weekend as the SSE direction takes over.
The remnant Pam increased in strength once again to the SE of French Polynesia 3/20. At the same time, a front pushing equatorward up from Antarctica merged with the remnant. This resulted in a massive low pressure cell. A wide, long fetch of severe gales to storm-forced winds aimed at the Americas, though close enough for angular spreading to provide surf locally. This source was much stronger than a system in the same area a few weeks ago that brought long period surf for several days from the SSE to Oahu. It could provide heights near the summer average.
The samoa buoy registered low swell energy from 160-170 degrees on Monday, which is a good sign that Hawaii will get it too. Low, long-period forerunners are due locally Thursday, with it filling in by Friday 3/27 from 160-170 degrees. It should be long-lived, holding about the same through the weekend. It should slowly decline next week.
Into the long range, a storm-force system on a zonal track SE of New Zealand just north of Antarctica 3/23-24 could keep summer background level surf locally next week 3/31-4/2 from 170-190 degrees.
The NW episode of Monday should steadily decline Tuesday 3/31, and fade out by 4/1. A lull in north Pacific surf is expected 4/2-3.
Windswell from 60-90 degrees should be below to near average 3/31-4/2.
This collaborative forecast will resume on Friday, March 27.
This forecast was produced through the collaborative efforts of NWS and NCDDC. Please send suggestions to email@example.com or call the Warning Coordination Meteorologist at 808-973-5275.
Additional resources: see /in lowercase/ http://www.prh.noaa.gov/hnl/pages/marine.php.
|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|