Big Picture

BIG Picture updated 11am, Sunday, June 14

Monday, July 15th – Tuesday, July 23rd

Trades moderating with increasing showers later in the week…

As is typical for this time of the year, ridging extends from the western coast of North America to Japan. This led to fresh paced ENE trades closer to home (15-25mph+) during the weekend. It should be similar on Monday and Tuesday. By midweek, a surface trough is predicted to form NE of Hawaii and traverse westward, remaining mostly north of the islands. This will briefly cause trades to weaken to moderate paces (10-20mph) and turn NE from Wednesday to Friday. The local trades should turn E-ENE at moderate to fresh paces (10-25mph) for the weekend into early next week as the trough slides downstream of Hawaii. Models build to ridge to a potent 1040 millibars by early next week, but a series of disturbances passing near the state should keep trades from becoming strong.

Isolated to scattered windward and mauka showers will accompany the trade wind flow through midweek. By Thursday and Friday, shower coverage may increase due to the nearby presence of a trough. Wetter than usual conditions could continue into early next week.

Surf Outlook –

North Shore: Seasonably flat conditions continue…

Recent/Now/Finally: Surf on Sunday was 0-1.5’ Hawaiian scale on the trade wind swell wrap. There were no sources of distant swell from the WNW-NNW since Jul 3. Surf should trend according to the trade wind swell, dropping to near flat towards midweek and rising back to 0-1.5’ towards early next week.

Outlook: Summery conditions consisting of tiny trade wind swell wrap should continue in the foreseeable future. There are hints that tropical cyclone activity could begin to increase over the far western end of the North Pacific towards the end of Jul. This area will be monitored for potential to send low, long period W-WNW swell during the first week of Aug.

South and West Shores: Big surf to start but trending down through the week…

Recent/Now (MODERATE): Surf on Sunday morning was 2-4’+ on two swells: a 15-16 second period SSW swell and a 18-20 second period SSW-S swell. The source of the SSW swell was a longwave trough passing New Zealand Jul 6-7 that set up a long, wide fetch of 35-45mph winds aimed at Hawaii. Long period forerunners arrived Friday, and it took all of Saturday to fill in. Surf from this source is peaking on Sunday as 18-22 second period energy from the SSW-S begins to increase on Sunday.

Next (LARGE): On Jul 7-8, the trough coalesced into a massive, high-end storm-force low (55-70mph). This monster fetch was aimed highest east of Hawaii. Satellite altimetry measured seas to 36’ Jul 8 but likely missed the largest waves. Even though American Samoa was well west of the fetch, its buoy still captured moderate energy Jul 11-12 (6-7’ of swell at 15-17 seconds). This raised the stakes for high surf in Hawaii, though it should be smaller than the Jun 14-15 South swell due to longer travel distance. Surf from this source should rise to 4-6’ by Sunday evening, peak overnight, and slowly drop on Monday to 4-6’. Heights should fall to 2-4 occ. 5’ early Tuesday, 2-3’ occ. 4’ early Wednesday, 1-2’ occ. near 3’ early Thursday, and 1-2’ occ. + early Friday. Surf should at background levels (2’ or less) for the weekend.

Finally: A more compact system developed over the central South Pacific Jul 11-13. It aimed two, side-to-side narrow fetches of 35-45mph to the north. It could bring 1-occ. 2’ surf from the S-SSE from Saturday to Monday.

Outlook: There is not much in store in the long term as the south Pacific storm track is predicted to become very zonal Jul 14-20. Small surf (~2-2.5’) from the SW-SSE could return locally towards Jul 27 and beyond as a series of compact systems could develop over the lower latitudes of the South Pacific.

East Shores: Smaller surf midweek…

Recent/Now/Finally: Surf on Sunday was 1-3’ on a 7-8 second ENE trade wind swell. Heights should be similar on Monday and drop Tuesday as the upstream trade fetch begins to weaken.  Surf should lower to 1-2’+ by late Tuesday and hold at 1-2’ late Wednesday to early Saturday due to lighter trades. It should rise on Saturday as the local and upstream trade winds strengthen. Heights should hold at 1-2’+ on Sunday and Monday.

Outlook: There is larger than normal uncertainty towards Tuesday and beyond. The GFS model depicts a stronger tropical disturbance approaching from the east, which would boost surf to 2-3’ by Jul 24-25. The EMCWF model is much weaker with the feature. In any case, surf should rise to at least near average (3’) by the middle of next week and beyond.

The next full SNN Big Picture will be issued on Sunday, July 21.

Forecaster Jonathan Huynh

Surf Climatology HERE

NEW NWS criteria for High Surf Advisories (first number) & Warnings (second number).

All surf height observations & forecasts are for full ‘face’ surf height, or ‘trough to the crest’ of the wave.

North-Facing Shores 15 Feet and 25 Feet

West-Facing Shores – Remaining Islands 12 Feet and 20 Feet

West-Facing Shores – Big Island 8 Feet and 12 Feet

South-Facing Shores -(Advisory) 10 Feet (up 2′) and (warning) 15 Feet

East-Facing Shores – 10 Feet (up 2′) and 15 Feet

Get the latest Central Pac Hawaii HERE

For the SNN Buoys ‘per shore’ displayed   HERE

Note: Spectral density graph in the SNN Buoy Page HERE can show ‘slivers’ of forerunners that initial text readings of new swells which often do not ‘show’ till later on written/text buoy updates.  Also, note the vertical graph is not ‘wave height’ rather its a measure of wave energy in hertz (frequency or cycles/sec) for the whole ‘band’ (the distribution of power/period in the total wave energy field/spectrum).

Back to Top