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SRFHFO

SURF ZONE FORECAST
NATIONAL WEATHER SERVICE HONOLULU HI
341 PM HST FRI DEC 14 2018

OAHU-
341 PM HST FRI DEC 14 2018

Surf along north facing shores will be 6 to 10 feet through Saturday.

Surf along west facing shores will be 3 to 6 feet through Saturday.

Surf along south facing shores will be 3 feet or less through Saturday.

Surf along east facing shores will be 4 to 7 feet tonight, becoming 3 to 5 feet Saturday.

Outlook through Friday December 21: The current northwest swell will continue to subside through Saturday, with a new, larger northwest swell expected to arrive late in the day Saturday, peaking at warning levels Sunday. Another, even larger, northwest swell is expected to build late Monday or Monday night, bringing another round of warning level surf to north and west facing shores Tuesday through the middle of 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, at the locations of the largest breakers. 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.


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SRDHFO

COLLABORATIVE NEARSHORE SWELL AND WIND FORECAST FOR OAHU
NWS/NCDDC HONOLULU HI
327 PM HST FRI DEC 14 2018

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
12/14
5NNW13810SAME17-21ENEDOWN
9ENE869SAME
SAT
12/15
5NNW1169DOWNLOW13-19ESAME
4NW22812UPLOW
7ENE846DOWNLOW
SUN
12/16
13NW183038DOWNLOW13-19EDOWN
6E724DOWNLOW
1SSW1423UPLOW
MON
12/17
9NNW141622DOWNLOW9-13EDOWN
4E712DOWNLOW
1SSW1323SAMELOW
TUE
12/18
4N1468DOWNLOW9-13NEUP
13NNW183038UPLOW
1SSW1212DOWNLOW
WED
12/19
14NNW153038DOWNLOW17-21NNEDOWN
7NNE724UPLOW

LEGEND:

SWL HGTOpen ocean swell height measured from trough to crestin feet located 20 nautical miles offshore
DMNT DIRDominant direction typically +/-10 degrees in 16 compasspoints
DMNT PDDominant period in seconds
H1/3Significant wave height in the surf zone
H1/10Average height in the highest one-tenth waves in the surfzone
HGT TENDHeight tendency of swell (valid values: UP/DOWN/SAME)
PROBProbability of occurrence (valid values: HIGH/MED/LOW)
WIND SPDOpen water wind speed measured in knots located20 nautical miles offshore
WIND DIRWind direction in 16 compass points
SPD TENDWind speed tendency (valid values: UP/DOWN/SAME)

Compass & Swell Shadow Lines for Hawaii

Oahu Surf Climatology

Surf heights will vary between different beaches and at the same beach at different break areas.

DISCUSSION: SUMMARY... Pair of winter-caliber events this period on N shores.

DETAILED:. Mid Friday on northern shores has breakers from 330-360 degrees below the seasonal average. Heights should trend down into Saturday mid day with a new event due Saturday PM.

NOAA NW Hawaii buoys 51001 and 51101 show an uptick in the 11-13 second wave periods Friday morning 12/14. A fast-moving low pressure with near gales passed eastward to the north of Hawaii with the fetch reaching to near 32N Wednesday night. This shorter-period pulse should trend down on Saturday.

A pair of broad, intense low pressure systems spaced two days apart with fast tracks from east of the Kuril Islands to the Gulf of Alaska are set to provide back- to- back well-above average episodes in Hawaii.

The first low pressure gained hurricane-force Wednesday night and maintained such strength into Friday along a 1500 nm track within 40-45N from the far western Pacific to north of Hawaii. The highest seas were best aimed at Hawaii up to the Date Line Thursday night over the 305-320 degree band. The JASON altimeter measured seas within 30-40 feet just east of the Date Line north of 40N Friday morning in an area about 1500 nm away. The low pressure is occluding mid Friday near 50N, 160W north of Hawaii. It is modelled to slowly drift NE and weaken late 12/14 into 12/16. The extreme winds covered a wide, long fetch east of the Date Line north of 40N though aimed more west to east at targets NE of Hawaii. Thus the closest high seas are expected to miss Hawaii to the immediate NE. This pattern makes for larger error bars on the local size estimate.

The long fetch of extreme winds has allowed extra-long wave periods to develop, which are due locally from 305-320 degrees Saturday afternoon. Heights should ramp up quickly into Saturday night well above average. The event is predicted to peak near dawn Sunday from 305-330 degrees. The neap tide status should lessen coastal wave run- up for the Sunday morning high tide, though wave wash should be above normal. Surf heights should remain extra-large into Sunday night though steadily decline Monday morning.

The fetch over the 320-350 degree band is expected to end late Friday 12/14 though a new fetch has set up on the NW side of the low north of 45N near the eastern Aleutians 12/14 and hold into 12/16. The 320-350 degree wave energy should steadily settle down Monday to below average by Monday night, then linger into Tuesday morning. Additional energy is expected from 350-010 degrees late Monday into Tuesday at levels below the seasonal average.

The second low pressure in the series is unfolding 12/14 east of the Kurils. Models show it becoming hurricane force late 12/14. It is expected to cross the Date Line near 45N late 12/15 and pass north of Hawaii early 12/17. The primary fetch is expected over the 310-330 degree band nosing to near 1200 nm away early Monday.

Extra-long period swell from this source is due Monday night with the event building above average by Tuesday dawn from 310-330 degrees. Heights should grow into the extra-large levels by late morning. The long-period phase of this event should peak Tuesday night from 310-330 degrees.

The primary low is predicted to move into the Gulf of Alaska Tuesday 12/18 as a front pushes SE to the north of Hawaii backed by strong to marginal gales to within 500 nm of Hawaii. Proximity of these high seas of more moderate-length wave periods should keep the surf extra large from 325-350 degrees with a peak near dawn Wednesday. Tides are waxing toward spring levels so above average coastal wave run-up is expected pre-dawn Wednesday.

Mid Friday on eastern shores has breakers from 60-90 degrees at levels above the trade windswell average. Heights are expected to drop on Saturday.

See the latest NWS State Forecast Discussion regarding the trend in the local winds and the expected weak frontal passage 12/18 PM.

ASCAT satellite Friday morning 12/14 shows fresh to strong breezes over and to the E to ENE of Oahu out 100 nm. Beyond that area, winds have been gentle to moderate for 36 hours. Thus the longer- periods of the windswell with 8-11s energy is expected to drop steadily late Friday into Saturday. Surf should drop to near the average late Saturday and below average by Sunday from 60-90 degrees.

Windswell associated with the frontal passage 12/18 should fill in late 12/18 and hold 12/19 from 350-030 degrees making for rough breakers on northerly exposures.

Mid Friday on southern shores has nil energy from the southern hemisphere. Conditions should stay at seasonal norms of near nil on Saturday.

A broad area of weak low pressure NE of New Zealand 12/9-11 could make for a minor event locally within 12/16-19 with small breakers for zones of high refraction, and negligible surf elsewhere.

Into the long range, no surf beyond tiny to small is expected from the southern hemisphere 12/20-22.

In the northern hemisphere, surf should trend down though stay above the seasonal average from 330-350 degrees Thursday 12/20 then near to below average from 330-010 degrees Friday 12/21. Hints of the next above average event roughly 12/23 from 305-330 degrees.

Moderate trades and below average windswell are predicted for 12/20-21.

Long range forecasts are subject to low confidence.

This collaborative forecast will resume on Monday, December 17.

This forecast was produced through the collaborative efforts of NWS and NCEI. Please send suggestions to w-hfo.webmaster@noaa.gov or call the Warning Coordination Meteorologist at 808-973-5275.

ADDITIONAL RESOURCES: See http://www.prh.noaa.gov/hnl/pages/marine.php

NWS Forecaster and NCEI Pat Caldwell

Additional Resources:

Waimea Buoy Kailua Buoy Kaumalapau SW Lanai Buoy Barbers Point, Kalaeloa Buoy Pauwela, Maui Hilo Bay Buoy Kaneohe Bay Buoy Hanalei Kauai Buoy Pearl Harbor Entrance
Buoy 51001 Buoy 51101 Buoy 51000 Buoy 51100 Buoy 51002 Buoy 51003 Buoy 51004

Latest North Pacific Surface Analysis

Upcoming tides for select Hawaii locations

Tides for Honolulu

Tide tables for Hawaii