Hawaii North Shore forecast by Steve Shearer (issued on Fri Jan 7)

This week and next (Jan7 – Jan14)

Hawaii: Flukey winds ahead as trades fail and an extremely active storm track ushers in overlapping pulses of XL to L surf from the NW

Solid combo swells in the 8-10ft range with bigger 12ft sets were on offer today. Winds were generally light, tending light NE before backing around to variable/easterly through the a’noon.

Size comes off todays peak into tomorrow with some still very solid 8-10ft sets, settling during the day into a slow easing trend.A trough to the North-East of the Islands will direct a weak, N’ly flow through tomorrow. Probably tending to light land breezes early and later with periods of light NW wind during the day.

Leftovers in the 6ft range then build rapidly through the day  as the start of a new L to XL event builds in. ASCAT passes show storm force winds in a wide band between 165-175E before the storm weakens as it tracks Eastwards, well north of the Islands.

Wave models have wound back the peak size of the swell into the 15-20 ft range, and with swell periods around 15 seconds and direction from the W/NW to NW it looks like a classic mid-sized Waimea swell. Breakers on the Outer Reefs may exceed those heights. Light and variable morning land breezes are likely to become variable through the day, clocking from N around to E and not exceeding 5-10knots.

Size then eases slowly through Mon with light E to E/NE winds providing classic conditions. Easing 12-15ft surf settles into the 10ft range during the day, favouring classic surf spots known to handle large NW swells like Sunset Beach. 

There’s not much let-up in the action next week. Storms have been spaced around 24-36hrs apart with each new fetch working on an already active sea state. This is producing overlapping swell trains, with consistent big surf expected across exposed North and West facing shores next week.

The next swell fills in Tues with size building back into the 12-15ft range, this dips briefly into Wed before another XL swell pushes heights back into the 15-18ft range, possibly with 20ft sets on Thurs. Winds look tricky to call with a wide model variance. Light and variable is the  most likely. These swells are being generated by intense storms exiting Japan and being absorbed into a continuing huge cyclonic gyre through the Northern Pacific.

The gyre breaks down later next week with a more “split” set-up across the North Pacific (see below). That looks likely to see a smaller period into next weekend. More storms off Japan later next week are shorter in duration and track in a more Northerly direction towards the Aleutians  after forming. That suggests a period of more moderate W/NW to NW swell into the week beginning 17/1. Overall storminess remains high, maintaining the overlapping swell pattern currently seen. Tradewinds show no sign of returning to climatological levels, with weak breezes into the medium term. Check back in Mon for the latest update.