Surf Forecast for O`ahu

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SRFHFO

SURF ZONE FORECAST
NATIONAL WEATHER SERVICE HONOLULU HI
400 PM HST FRI MAY 22 2015

OAHU-
400 PM HST FRI MAY 22 2015

Surf along north facing shores will be 3 to 5 feet this afternoon and rise to 4 to 6 feet Saturday.

Surf along west facing shores will be 2 to 4 feet through Saturday.

Surf along east facing shores will be 2 feet or less this afternoon and rise to 2 to 4 feet Saturday.

Surf along south facing shores will remain at 3 to 5 feet then rise to 4 to 6 feet late Saturday afternoon.

Outlook through Thursday May 28: a series of small, somewhat out of season northwest and west northwest swells will continue through next week. A series of small south to south southwest swells also will continue through next week. Surf along south facing shores will approach high surf advisory levels Tuesday into Tuesday night.

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
300 PM HST FRI MAY 22 2015

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
05/22
3SW1546SAME4-6VRBSAME
SAT
05/23
4NNW1157UPLOW9-13NNEUP
5N946UPMED
2SSE1324UPLOW
3SW1446SAMEMED
2SSW2046UPMED
SUN
05/24
3NNW1024DOWNMED9-13NNESAME
5NNE1057SAMEMED
3SSW1757UPLOW
2SSW2248UPLOW
MON
05/25
4NNE1046DOWNLOW4-6VRBSAME
4SSW1468DOWNLOW
3SSW1757UPLOW
2WNW1424UPLOW
TUE
05/26
3NNE813DOWNLOW4-6VRBSAME
4SSW1568SAMELOW
2WNW1324SAMELOW
WED
05/27
3NW1235SAMELOW7-10NEUP
3NE712SAMELOW
3SSW1346DOWNLOW

LEGEND:

SWL HGTOPEN OCEAN SWELL HEIGHT MEASURED FROM TROUGH TO CREST IN FEET LOCATED 20 NAUTICAL MILES OFFSHORE
DMNT DIRDOMINANT DIRECTION TYPICALLY +/-10 DEGREES IN 16 COMPASS POINTS
DMNT PDDOMINANT PERIOD IN SECONDS
H1/3SIGNIFICANT WAVE HEIGHT IN THE SURF ZONE
H1/10AVERAGE HEIGHT OF THE HIGHEST ONE-TENTH WAVES IN THE SURF ZONE
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 LOCATED 20 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

SURF HEIGHTS WILL VARY BETWEEN DIFFERENT BEACHES AND AT THE SAME

BEACH AT DIFFERENT BREAK AREAS.

DISCUSSION:

Summary: short-period N and long-period S.

Detailed: mid Friday on northern shores has near flat conditions. A rise is imminent.

Overlapping events are expected for the weekend with surf near to a notch above the may average.

A near gale low approached the dateline near 50 N Monday. It tracked east towards the eastern Aleutians into Wednesday as a front pushed SE, backed by strong breezes to near gales over the 320-340 degree band, reaching about 1000 nm away late Wednesday.

The swell was modelled to arrive on Friday 5/22 though no sign is seen in the pacioos/cdip Hanalei, Kauai buoy as of the morning. It should fill in to Oahu overnight. It should peak on Saturday then drop on Sunday.

A low pressure cell formed along the front N of Oahu near 30°N late Thursday. It is occluding NNE of Oahu on Friday 5/22. It is modelled to slowly drift E and weaken by Monday.

Ascat satellite showed strong to near gale winds over the 000-020 degree band late Thursday and Friday morning, with the head of the fetch about 600 nm away. Short-period surf from this source is expected to pick up early Saturday, peak on Sunday, then drop on Monday from 000-020 degrees.

The weekend should see shorter-period energy in the 6-8 second band from 330-020 degrees from closer N winds. This would make for less lined-up breakers.

Typhoon dolphin in the W Pacific near 20°N, 140°E 5/17-18 could give low, long-period swell from 270-290 degrees picking up late Sunday. The system weakened as it absorbed into a mid latitude low pressure cell E of the Kuril Islands 5/19-20. A broad area of low pressure has set up a larger fetch aimed well NE of Hawaii. Short- to moderate-period low swell from 300-320 degrees should take over by Tuesday and hold Wednesday from angular spreading.

Mid Friday on southern shores has breakers near to a notch above the March to October seasonal average. Similar surf is likely on Saturday with an upward trend.

Austral fall season is active for surface low pressures in the mid latitudes for longitudes from Tasmania to French Polynesia. The pattern is holding into next week. A long-lived spell of average to above average southerly surf is expected this period and into the long range.

A low pressure near New Zealand moved slowly east 5/13-16 while a front pushed equatorward west and north of New Zealand. Surf from this source picked up locally 5/21 from 200-220 degrees. It is holding about the same on Friday. The pacioos/cdip buoy near american samoa held steady energy levels in the 12-16 second band 5/18-20, which suggests this episode will stay about the same Saturday into Sunday with a backing in direction to 190-210 degrees.

A new episode is showing up in the 19-21 second band of NOAA buoy 51002 south of Oahu mid Friday. This is the first of two long-period events due over the weekend.

The sources were winter-caliber low pressure systems tracking east near 60 S to the SW to SE of New Zealand 5/15-19, spaced about 1.5 days apart.

The first event had 35 feet seas SE of New Zealand about 4500 nm away 5/16. The system weakened as it continued east 5/17.

The pacioos/cdip samoa buoy had 16-18 second wave periods arriving 5/19 with the 12-16 second energy peaking 5/20. The former have about a 3 day travel and the latter, 4 days. The episode should trend up locally above average Saturday into Sunday, peak mid Sunday, and drop Monday from 180-200 degrees.

The second system was strongest SE of New Zealand 06Z 5/18, or Sunday evening locally. Jason satellite validated seas over 40 feet in an area about 4500 nm away. The low center jogged NE and weakened rapidly 5/18-19. If it could have maintained the original strength, then the surf potential would have reached extra-large. But in this case, then weakened status suggests an above average event on caliber with the other larger southerly events that have occurred in spring 2015.

The samoa buoy did register long-period swell of 18-22 seconds starting 5/21, of much more size than the first event. On 5/22, the energy has backed down within 18-22°S and has risen in the 16-18 S band similar to the first event.

This suggests the onset of the second event should be robust locally on Sunday 5/24 from 190-200 degrees with 18-25°S energy. Sets should be inconsistent, but extra-powerful with the greater shoaling and refracting factor associated with extreme wave periods.

The second event should peak late Monday, hold similar Tuesday, and slowly drop Wednesday from 180-200 degrees.

Saturday through Tuesday should have more consistent arrival of set waves due to the overlapping episodes. More frequent waves gives way to stronger currents in the surf zone.

Into the long range, the second system merged with a secondary low pressure cell 5/19 south of French Polynesia. Gales over the 170-185 degree band 5/19-20 were about 4000 nm away. This should keep surf locally average to a notch above average 5/28-29 from 170-200 degrees.

Another large scale jet trough and combined areas of surface low pressure all around New Zealand starting 5/21 have various sources that should keep average surf 5/29-30 from 190-220 degrees. Models show the pattern shifting east 5/24-26, away from the New Zealand shadow, while strength remains winter-caliber. Such a pattern would make for well above average surf from 180-200 degrees 5/31-6/2.

In the northern hemisphere, another weak low is modelled near the dateline by the Aleutians 5/25. This could give a small NNW event 5/29-30. Also Monday into Tuesday to the NNE of Hawaii, a weak low is modelled. It could give a small NNE event 5/28-29.

Long range forecasts are subject to high uncertainty.

This collaborative forecast will resume on Tuesday, 5/26.

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

Additional resources: see /in lowercase/ http://www.prh.noaa.gov/hnl/pages/marine.php.

NWS Forecaster and Pat Caldwell, Pacific/Hawaii Liaison Office, NCDDC

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

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