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SRFHFO

SURF ZONE FORECAST
NATIONAL WEATHER SERVICE HONOLULU HI
323 PM HST MON AUG 20 2018

OAHU-
323 PM HST MON AUG 20 2018

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

Surf along east facing shores will be 2 to 4 feet tonight, increasing to 3 to 5 feet Tuesday.

Surf along west facing shores will be 2 feet or less through Tuesday.

Surf along north facing shores will increase to 1 to 3 feet tonight, and 4 to 6 feet Tuesday.

Outlook through Monday August 27: Choppy surf along east facing shores will gradually increase this week as trade winds strengthen. Most importantly, Hurricane Lane is forecast to pass south and southwest of the islands this week, and will likely deliver increasingly rough surf to south facing shores as the week progresses. Be sure to monitor forecast updates on Lane as it could bring significant impacts later this 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
306 PM HST MON AUG 20 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
08/20
5E724SAME13-19EUP
TUE
08/21
3NNW1346UPMED17-21EUP
7E734UPMED
WED
08/22
4N1368DOWNMED19-23ENEUP
8E846UPLOW
6SE131012UPLOW
THU
08/23
3N1146DOWNLOW22-27NEUP
10ENE868UPLOW
12SE121520UPLOW
FRI
08/24
10E10810DOWNMED22-27EDOWN
12S121520DOWNLOW
SAT
08/25
8ENE846DOWNLOW17-21EDOWN
6S12812DOWNLOW

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:. North swell and hurricane surf.

DETAILED:. Mid Monday on northern shores has near flat conditions. An increase is predicted for Tuesday.

An occluded low pressure just south of the Aleutians north of Hawaii 8/17-19 had a large fetch of near gales with pockets to gales. The slow-moving low pressure pattern made for a long fetch duration over the 345-360 degree band. Surf is modelled to build Tuesday, peak Tuesday night, then slowly drop into Thursday.

Mid Monday on eastern shores has breakers from 70-90 degrees below the trade windswell average. An increase is expected for Tuesday.

See the latest Central Pacific Hurricane Center (CPHC) statements concerning hurricane Lane.

Based on the 11 AM HST 2018-08-20 CPHC official forecast intensity and track of Lane, rough surf is predicted for the eastern exposures of Oahu beginning Wednesday as heights climb above average. The official track keeps Lane south of Oahu as it tracks toward the NW to NNW Thursday into Friday. This scenario means less surf from 40-90 degrees. Stay tuned for updates from the CPHC since changes in intensity and track of Lane translates into changes to the surf forecast.

Conditions are expected to trend down though remain above average Friday into Saturday.

Mid Monday on southern shores has a seasonal minimum of surf. Similar low surf is predicted for Tuesday.

No surf beyond tiny is predicted from the southern hemisphere this period.

The 11 AM 8/20 CPHC forecast of Lane would give building surf above average Wednesday from 130-160 degrees. Rough, large, hurricane surf is predicted to hold Thursday, peak late Thursday from 140-180 degrees, and slowly decline Friday into Saturday though still above average. Disclaimers on uncertainties apply to the south shore as with the east shore aforementioned. Stay tuned to the latest updates.

Into the long range, gales in the Tasman Sea 8/19-20 could give low, long-period swell locally 8/27-28 from 208-220 degrees at levels below the summer average.

North shores are expected to stay at summer levels 8/26-28.

East side is expected to remain near to above average 8/26-28 from 50-90 degrees.

Long range forecasts are subject to major revisions.

This collaborative forecast will resume on Wednesday August 22 or sooner if changes occur in CPHC forecasts of Lane.

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 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

Latest North Pacific Surface Analysis

Upcoming tides for select Hawaii locations

Tides for Honolulu

Tide tables for Hawaii