Surf Forecast for O`ahu

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SRFHFO

SURF ZONE FORECAST
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST WED JUL 30 2014

OAHU-
400 AM HST WED JUL 30 2014

Surf along south facing shores will be 2 to 4 feet today, increasing to 3 to 5 feet Thursday.

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

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

Surf along north facing shores will remain nearly flat through Thursday.

Outlook through Tuesday August 5: a series of small south swells will continue through the rest of the week. Prevailing trade winds will continue to produce short period, choppy surf along east facing shores.

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, in the zone of maximum refraction. 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 MON JUL 28 2014

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
07/28
5E824SAME12-18ESAME
2SW1424DOWN
TUE
07/29
5E824SAMEMED12-18ESAME
2SSW1424UPLOW
WED
07/30
5E824SAMEMED13-19EUP
2SSW1424DOWNLOW
THU
07/31
6E834UPLOW13-19ESAME
2SSW1535UPLOW
FRI
08/01
6E834SAMELOW13-19ESAME
3SSW1546UPLOW
SAT
08/02
7E835UPLOW17-21EUP
2E1124UPLOW
4SSW1457UPLOW

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: steady easterly and southerly swell at common summer levels with upward trends for both approaching the weekend.

Detailed: mid Monday on eastern shores has short-period breakers below to near the summer average level from 70-90 degrees. Similar surf is expected on Tuesday.

An upper level low pressure cell over the gulf of Alaska and its associated trough stretching SW towards Hawaii have weakened the seasonally-permanent surface high pressure area to the N through NE of Hawaii. It is expected to hold 7/28-8/1. This pattern alone would give below average summer trade wind speeds in the gentle to moderate bracket. However, winds over and E of Hawaii are stronger due to tropical influences.

A string of westward-moving, weak tropical surface low pressure cells to the S to SE of Hawaii over the roughly 10-15°N latitude band are enhancing the trades with increasing speeds with decreasing latitudes. With the elusive nature of these tropical features, frequent forecast updates are necessary. See the latest updates and explanations in the NWS Hawaii state forecast discussion.

The enhanced trades east of Hawaii have added energy to the 8-12 second band as measured by the mokapu buoy off windward Oahu on 7/28. The magnitude is too low to surpass average summer conditions. This longer period windswell should continue off and on through the week. Low energy in the 10-12 second band from tropical system Hernan WNW of Baja is modelled for late Friday into Saturday.

The dominant energy in the windswell is in the 6-8 second band associated with the winds over to within a few hundred miles E of Oahu. These winds 7/29-8/1 are expected to vary within moderate to fresh in speed and 60-100 degrees in direction, with subtle changes associated with the tropical features passing to the south. Models suggest Oahu trades to increase a notch for Wednesday into Saturday, with a slight uptick to the surf from short-period windswell.

Mid Monday on southern shores has surf below to near summer average levels for top spots favoring Tasman swell from 208-220 degrees. The dominant direction is predicted to shift to 190-200 degrees on Tuesday.

A long-lived jet stream trough east of New Zealand 7/21-28 had various surface low pressure cells and fronts unfold, though for the most part, they were wind speed magnitude deficit. Thus, the upcoming episodes are not expected to extend much beyond the common summer levels 7/29-8/2. Overlapping episodes are expected as a combination of the closer sources with shorter dominant periods within 13-16 seconds, and sources closer to Antarctica adding low, long-period swell of 17-22 seconds. All should hover within 180-200 degrees and stay active 7/29-8/2. Only the closer, larger sources are described below.

A narrow fetch of gales hugged the east side of New Zealand as a front pushed equatorward 7/21-22. Surf from this source is expected to build on Tuesday from 190-200 degrees with 13-15 second intervals. It should hold through Wednesday.

A surface low pressure cell formed off this front 7/22 to the ENE of New Zealand, and tracked east along 35°S. A compact area of gales over the 180-195 degree band was duration limited due to the lack of captured fetch, the head of which was about 3500 nm away by 7/24. This source should fill in on Thursday and hold into Friday with 14-16 second periods.

A pair of low pressure cells and front pushed NNE just E of New Zealand 7/24-26 making for a captured fetch of near gales to gales that stretched about 1800 nm into the subtropics over the 190-200 degree band. This source should be the largest with moderate period energy filling in late Friday afternoon. The episode should peak on Saturday above the summer average.

Into the long range, with the long fetch of the 7/24-26 pattern E to NE of New Zealand, the episode should be long-lived, holding average to above average 8/3-4 from 190-200 degrees.

The jet stream trough near New Zealand shifted eastward 7/26-28 to SSE of French Polynesia as a surface low pressure deepened to severe gale status. It tracked steadily east along 45°S with a strengthening trend as it passed east of the Hawaii swell window 7/28. Long period forerunners from this source should fill in 8/3 from 180-190 degrees, peak on 8/4 near to above summer average heights, and slowly decline into 8/6 from 170-190 degrees.

Moderate to fresh trades with average summer windswell from within 60-90 degrees is expected 8/3-5.

No surf beyond tiny is expected from the W through NNE on northern shores.

Long range forecasts are subject to major revisions.

This collaborative forecast will resume on Wednesday, July 30.

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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