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SRFHFO

SURF ZONE FORECAST
NATIONAL WEATHER SERVICE HONOLULU HI
333 AM HST WED MAR 20 2019

OAHU-
333 AM HST WED MAR 20 2019

Surf along north facing shores will be 7 to 10 feet this morning, rising to 15 to 20 feet this afternoon, lowering to 12 to 16 feet Thursday.

Surf along west facing shores will be 3 to 6 feet this morning, rising to 10 to 15 feet this afternoon, lowering to 8 to 12 feet Thursday.

Surf along east facing shores will be 2 to 4 feet through Thursday.

Surf along south facing shores will be 1 to 3 feet through Thursday.

Outlook through Wednesday March 27: Surf will remain up around advisory levels for north and west facing shores Friday through the weekend as overlapping north to northwest swells continue. The first reinforcement is expected Friday into Friday night with the second swell building over the local waters Sunday. Surf along east facing shores will build Friday through the weekend as strong trades return. South shore surf is expected to remain small through early 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
313 PM HST MON MAR 18 2019

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
03/18
13NNW152634DOWN11-16NEDOWN
TUE
03/19
8NNW131418DOWNMED7-10EDOWN
4N1268UPLOW
WED
03/20
8NW171620UPLOW4-6VRBSAME
4N1168DOWNLOW
THU
03/21
8NNW141418SAMELOW11-16ENEUP
FRI
03/22
8NNW141418SAMELOW17-21ENEUP
6ENE724UPLOW
SAT
03/23
7NNW141216DOWNLOW17-21ENESAME
7ENE846UPLOW

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:. Active NW to N for the season transition.

DETAILED:. Mid Monday on northern shores has breakers from 310-360 degrees at extra-large levels, meaning high enough to break on outer reefs. Heights are expected to remain elevated with a downward trend into Tuesday.

The pattern that produced the giant surf 3/17-18 was a combination of remote and nearby generated seas and swell. The remote portion favored 310-330 degrees. With the long travel distance, the swell trains are spread over a larger area as they disperse, or travel away from the generation area with longer wave periods moving faster. This gives another day for the moderate period swell of 13-15 seconds from 310-330. It should remain above the March average Tuesday morning with a steady decline below average by late Tuesday afternoon.

A long fetch of strong to near gale breezes set up north of Hawaii to the Aleutians Saturday night into Sunday morning. This should give shorter-period surf from 350-010 degrees building Monday and dropping Wednesday.

The north Pacific pattern is finishing off the winter season with an active cyclonic mode in the central to northeastern basin. A low pressure gained strength near 45N, 160E 3/16 and had seas approaching 30 feet by 3/17 in an area about 2000 nm away. The low maintained storm-force as it crossed the Date Line Sunday night. It is expected to slow in track as it aims less at Hawaii late Monday into Tuesday 3/18-19.

Long-period forerunners from 305-320 degrees are modelled to fill in Wednesday morning, with surf climbing above average in the afternoon. The event should peak Wednesday night from 310-330 degrees.

Another low pressure is forming Monday 3/18 near 35N, 165E. It is modelled to merge with the former low to the north of Hawaii just south of the Aleutians Tuesday as the combined systems become one large gyre with a slow NE drift into Friday. This should make for a long- lived fetch area over the 320-350 degree band. Surf from this source should overlap the mid week event, keeping surf above average Thursday PM into Saturday morning. Fine tuning on specifics can be given once the event unfolds.

Mid Monday on eastern shores has near nil energy from the trade wind belt of 50-90 degrees. Exposures to northerly swell are above average with a trend aforementioned.

Trades are predicted to build Thursday into Friday locally to fresh levels and hold into the weekend. This should trend the surf up Friday into Saturday to above the trade windswell average from 50-90 degrees.

Mid Monday on southern shores has seasonally minimal surf. Low conditions are expected to continue on Tuesday.

No sources in the southern hemisphere last week are identified to give surf beyond the seasonal background levels of mostly flat with select areas in the tiny to small bracket this week.

Into the long range, background levels from 180-220 degrees could pick up slightly with 3/25-29 but not surpass the small bracket. This would be from a series of storm-force systems tracking rapidly east south of New Zealand hugging the Antarctic ice sheet this week.

In the north Pacific, models suggest below average N to NNE surf 3/24-26 under fresh to strong trades, with windswell from 30-60 degrees remaining above average.

Long range forecasts are subject to major revisions.

This collaborative forecast will resume on Wednesday, March 20.

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