National Weather Service United States Department of Commerce

Surf Forecast for Oahu  Issued: 10/22/2019 03:38:53 AM HST

Surf Discussion for Oahu  Issued: 10/21/2019 02:44:53 PM HST


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SURF ZONE FORECAST
NATIONAL WEATHER SERVICE HONOLULU HI
338 AM HST TUE OCT 22 2019

OAHU-
338 AM HST TUE OCT 22 2019

Surf along north facing shores will be 2 to 4 feet today, then 3 to 5 feet Wednesday.

Surf along west facing shores will be 2 feet or less today, then 1 to 3 feet Wednesday.

Surf along south facing shores will be 2 to 4 feet today, then 1 to 3 feet Wednesday.

Surf along east facing shores will be 3 to 5 feet through Wednesday.

Outlook through Tuesday October 29: After small surf today, a series of northwest swells is set to start coming in over the coming days with each bump being a little bit larger. A small bump first rolls in on Wednesday followed by a moderate northwest swell on Friday. Then, on Saturday night, a large northwest swell arrives, bringing advisory level surf to the north and west facing shores between Sunday and Tuesday. This swell will peak Monday before trending down slowly.

Locally strong trade winds will maintain mainly moderate level surf along east facing shores through Wednesday, followed by slightly smaller surf during the second half of the week as the trades become lighter. A small background swell will maintain small surf for the south facing shores through the rest of the period.

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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COLLABORATIVE NEARSHORE SWELL AND WIND FORECAST FOR OAHU
NWS/NCDDC HONOLULU HI
244 PM HST MON OCT 21 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
10/21
2NNW1124SAME11-16EUP
5ENE824SAME
2S1435SAME
TUE
10/22
2NNW1124SAMELOW13-19EUP
6ENE835UPLOW
2S1224DOWNLOW
WED
10/23
3NNW1146UPLOW11-16EDOWN
6ENE835SAMELOW
2S1013SAMELOW
THU
10/24
2SSW1624UPLOW7-10EDOWN
3NNW1246UPLOW
4ENE935SAMELOW
FRI
10/25
6NNW11812UPLOW9-13EUP
4ENE935SAMELOW
SAT
10/26
6NNW11812DOWNLOW11-16EUP
4ENE935SAMELOW

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:. Surf from around the compass.

DETAILED:. Mid Monday on southern shores has breakers from 170-190 degrees at levels near the average. Heights should drop below average on Tuesday.

A large batch of seas above 30 feet were generated 10/11-13 well SE of New Zealand at the eastern edge of the Hawaii swell window. This event filled in locally 10/19-20 centered near 180 degrees. The event is holding 10/21 with energy in the 12-16s band. It could linger within background to average on Tuesday then fade on Wednesday.

No sources beyond background are expected locally 10/24-26 based on the benign weather pattern SW and SE of New Zealand 10/15-18.

Mid Monday on eastern shores has breakers from 60-90 degrees a notch under the average. An increase is predicted for Tuesday.

Surface high pressure of 1031 mb 10/21 near 35N, 135W has held steady a few days and is expected to slowly move east this week. A long-lived, long, wide fetch of fresh to strong trades east of 145W are expected to make for a long-lived spell of breakers locally near the average through the week into the weekend out of 60-90 degrees.

See the latest NWS State Forecast Discussion regarding the trend in the local winds.

Mid Monday on northern shores has breakers from 315-360 degrees at levels below the October average. More of the same is predicted for Tuesday.

A wide, long fetch of fresh to strong breezes, with small pockets to near gales, moved east from the Kuril Islands 10/17-19 with the head of the fetch crossing the Date Line Saturday. A blocking ridge east of the Date Line sent various small low pressure cells to the NE towards the Gulf of Alaska with fronts backed by fresh breezes nosing to about 1000 nm out 10/19-20. This should bring in remote windswell locally from 310-360 degrees with a trend up Tuesday into Wednesday. Peak heights are predicted below the October average.

A low pressure tracked east from the Kuril Islands along 40N 10/19-20. ASCAT satellite showed an area of gales to severe gales out near 160E 10/20. ASCAT showed a weakening by 10/21 as the low approached the Date Line. Seas grew only to about 20 feet beyond 2000 nm away. Only a small bump is expected from 300-315 degrees building Thursday and dropping Friday from this direction, as surf from more N direction takes over.

The low at the Date Line 10/21 is modelled to intensify as it races towards the Gulf of Alaska into 10/22. Gales are expected over a fetch of limited duration and length due to the fast motion and track across the great circle rays within 320-360 degrees. Thus, only below average surf is expected from this source on late Thursday into Friday from 320-360 degrees.

But wait, there's more. A new low pressure is modelled to form near 35N, 155W Wednesday 10/23 within 1000 nm of Hawaii. Near gale winds over a long fetch acting upon existing seas from the aforementioned system are expected to aim slightly west of Hawaii 10/23-24, similar to a source that brought in the first overhead NNW to N surf locally September 27.

This event is predicted to build Friday, peak Friday night above average, then drop Saturday from 330-360 degrees.

Into the long range, tropical storm Neoguri SE of Japan 10/21 is modelled merge 10/23 with a mid latitude trough near the Kurils, with the tropical moisture fueling a storm-force system by 10/24. The low pressure is predicted to occlude near 45N, 170E 10/24, then slowly move NNE into 10/27. A long, wide fetch of gales to severe gales, with pockets to storm-force are predicted 10/24-25, with a slow weakening trend into 10/27. It should make for a long- lived, above average event. Long-period forerunners are due early Sunday with surf building above average 10/27 PM from 300-315 degrees. Heights should climb to winter norms 10/28-29 from 325-330 degrees.

A series of marginal gale low pressure systems near New Zealand are modelled this week that suggests a return to at least background to average surf within 10/30-11/4 from 180-200 degrees.

East side is predicted to remain near to a notch below average 10/27-28 from remote trades.

Long range forecasts are subject to low confidence.

This collaborative forecast will resume on Wednesday, October 23.

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 https://www.weather.gov/hfo/marine

NWS Forecaster and NCEI Pat Caldwell

Additional Resources:

Waimea Buoy Mokapu Point 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

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