SURF ZONE FORECAST
NATIONAL WEATHER SERVICE HONOLULU HI
400 PM HST WED OCT 1 2014
400 PM HST WED OCT 1 2014
HIGH SURF ADVISORY FOR SOUTH FACING SHORES
Surf along south facing shores will be 7 to 9 feet tonight, decreasing to 6 to 8 feet Thursday.
Surf along east facing shores will be 2 to 4 feet through Thursday.
Surf along north facing shores will be 6 to 10 feet tonight, decreasing to 5 to 8 feet Thursday.
Surf along west facing shores will be 5 to 8 feet tonight, decreasing to 4 to 6 feet Thursday.
Outlook through Tuesday October 7: advisory level surf will continue over south facing shores through Thursday, then decline Thursday night and into the weekend. A series of small to moderate northwest swells will continue into next week.
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 OCT 1 2014
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 pattern in both hemispheres for Hawaii surf.
Detailed: mid Wednesday on southern shores has surf above the southerly surf season average from 180-200 degrees with 16-22 second intervals. Heights are expected to remain above average on Thursday.
Longitudes from Tasmania to French Polynesia in the mid latitudes have favored troughs at the jet stream level and seasonally strong low pressures at the surface. This pattern is expected to continue into the long range. It is making for a more consistent pace of southerly episodes for early fall than usual.
A storm-force low pressure tracked east along 55°S south of New Zealand with seas above 35 feet 9/22. The track turned more ENE as it moved SE of New Zealand, setting up a captured fetch for the 190-200 degree band. The head of the fetch reached to 40s east of New Zealand 9/24 with seas near 30 feet. This is the source for the high surf locally of 9/30-10/1.
The pacioos/cdip Barbers Point near shore buoy shows dominant energy in the 16-22 second band during the morning of 10/1. Since the wave periods are long, dispersion ensures at least another day of surf of similar or slightly less size. Dispersion means the spreading of wave energy by wave period, and with the long travel distance, the patch of swell energy covers a broad region, making for long-lived events.
The low pressure associated with this source passed east of the longitude of Hawaii near 160°W on 6/25 to the south of French Polynesia with seas aimed more at the Americas. The fetch remained large and angular spreading should keep surf locally active into Saturday. There should be a slow decline Thursday night into Saturday from 180-190 degrees.
The next system that passed S to SE of New Zealand 9/27 had a similar track and captured fetch into 9/29. However, the magnitude of the surface winds was weaker. The gales produces seas within 20-24 feet. The ideal location and track should at least bring surf near the seasonal average starting Monday 10/6 from 185-200 degrees, lasting a couple of days.
Mid Wednesday on eastern shores has near flat surf except for locations open to refraction from north or south. Surf is expected to remain below the trade windswell average through the period.
Mid Wednesday on northern shores has surf out of 310-320 degrees above the early October average, which is 9 feet peak face at top spots for the h1/10th sets, or the common though less frequent higher set waves. Surf is expected to be near the early October average on Thursday.
The northern hemisphere is also having an active pattern in the tropical western Pacific and mid latitude zones from longitudes of Japan to north of Hawaii. This should give way to a consistent pattern of surf this period, though heights near to below the early October average.
A new episode filled in locally on Tuesday 9/30 from 305-315 degrees with 17-20 second intervals. The source was a hurricane-force system that formed just SE of Kamchatka last Friday 9/26. Seas grew above 35 feet by Saturday morning as the system occluded in a region about 2400 nm away. This phase of the weather pattern produced the long-period swell, which arrive Tuesday and is slowly dropping in dominant wave period on Wednesday 10/1. It has already peaked.
The occluded low pressure system became broad with a wide, long fetch over the 310-320 degree band aimed at Hawaii 9/28, yet the surface winds speed dropped off severely, down to low-end gales. Seas dropped quickly below 25 feet by mid day 9/28 while still beyond 2000 nm. The massive gyre slowly drifted east 9/28-9/30 as fetch was added for the 315-330 degree band. The latter phase should equate to shorter wave periods. Moderate periods of 12-14 seconds are expected on Thursday, with a steady decline in wave periods into Saturday. The event should be long-lived, though surf size slowly declining over the same period from 310-330 degrees. A new event is due Friday afternoon.
Typhoon kammuri turned back toward the east to the SE of Japan 9/27. The system quickly became extra-tropical as the surface wind speeds decreased. Ascat estimates of the surface winds showed the strongest speeds aimed north of Hawaii. Angular spreading could bring in some low, long-period swell from 280-300 degrees on Friday.
Strongest speeds continued to aim north of Hawaii as the remnant low pressure tracked rapidly east 9/28-10/1. The long fetch aimed at Hawaii had marginal gales. Models suggest surface wind speeds continuing to decline 10/2 as it lifts to the NE just east of the dateline.
Moderate period swell of 12-15 seconds are expected to fill in locally on Saturday from 290-310 degrees with heights peaking near or just under the early October north shore average. Heights should slowly fall Sunday into Monday from the same direction.
Models show a new amplifying jet-level trough just east of the dateline Friday and a near gale surface low pressure tracking east along 45°N 10/3-5. This should bring a short to moderate period swell building Monday from 330-340 degrees.
Into the long range, the new episode on Monday should be short-lived, peaking Monday night, and dropping on Tuesday from the same direction likely below the early October average. Models suggest a stronger than normal Aleutian low pressure gyre from the surface to upper levels centered on the dateline 10/6-10. Models hint at potential for typhoon phenfone to be drawn into the large scale mother low as it curves off Japan early next week. This pattern suggests above October average surf locally 10/9-12 from WNW to NNW.
In the southern hemisphere, a hurricane-force system in the southern Tasman sea could produce low, long-period swell locally by 10/9 with heights near the summer season average into 10/10 from 210 degrees.
Light to gentle winds are expected to keep easterly windswell near nil 10/7-9.
Long range forecasts are subject to major revisions.
This collaborative forecast will resume on Friday, October 3.
This forecast was produced through the collaborative efforts of NWS and NCDDC. 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.
|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|