Hawaii North Shore forecast by Steve Shearer (issued on Fri 31 Dec)

This week and next (Dec31 – Jan7)

Hawaii: Small NW pulses this weekend with good winds, a few dodgy days then more N swell and then stronger back to back to back W/NW swells next week

No change to the weekend f/cast with fun levels of 3-4ft NW swell New Years Day, with lighter winds tending more SE as weak low pressure  to the NW of Hawaii drags the trade flow to a more SE-NW angle. This swell should ease slowly Sun with plenty of fun surf on hand. 

Stronger surf fills in next week as a more winter-calibre storm pattern begins to set in, with storms off Japan following a favourable jet stream pattern. That sees storms tracking directly at Hawaii, before veering away to the N once they approach the dateline. 

The first cab off the rank sees gales and severe gales off Honshu on the weekend, maintaining a compact but storm force fetch as the low then tracks NE on Tues. Long period forerunner build late Tues with the bulk of the swell in the 14-16 period band fills in Wed, with surf building into the 6ft+ range .

This swell will blend with N’ly groundswell generated by an intense winter storm off the Alaskan Peninsula Sun/Mon, which weakens from storm force but which develop an incredible long fetch down the Eastern Pacific. This will supply surf in the 3-5ft range. Winds are funky Wed as a decaying trough brings a N’ly flow, before E/NE trades re-establish.

A much stronger pulse of NW swell from the same system Thurs is expected to see surf in the 10ft range, with E’ly trades re-establishing as high pressure slips to the NE of Hawaii.

A long lasting storm tracking behind the previous system exits the Kurils on Mon, tracking towards Hawaii with a board fetch of gales. This low then becomes absorbed into a huge cyclonic gyre consisting of multiple low centres covering almost the entire North Pacific with a massive area of 20-30ft seas expected. Multiple fetches from this gyre operate on an active sea state through next week, with a series of W/NW to NW pulses incoming. 

Thats expected to see surf in the 10 ft range Fri, slowly easing before rebuilding Sat. A larger pulse borderline XL pushes surf into the 15ft range Sat, with Outer reefs likely to break. 

Longer term, the cyclonic gyre breaks down towards the end of next week suggesting a slow ramp down in wave heights from next weekend. 

Check back Mon for a fresh update.