The Billabong Pipeline Masters Trials kicked off today in great conditions - NW groundswell, light trades - and the good run looks set to continue. We've got a couple of excellent days of surf ahead, followed by an XXL groundswell that could see the cbdMD Jaws Big Wave Championships get the green light - and make Trials winner and defending Jaws champion Billy Kemper a busy lad.

As talked about in the early forecast last week, a reinforcing mid-period NW swell is expected tomorrow to 6-8ft with great morning east-southeast offshores, shifting to north-east trades into the afternoon. That prediction hasn't changed.

However, moving into Wednesday and Thursday, our NW groundswell has been upgraded to an XXL swell event from a more N/NW direction.

A significant storm forming to the south-east of the Kamchatka Peninsula has already generated a fetch of severe-gale to storm-force W/NW winds in Hawaii's far north-western swell window - see image above - and the progression is now swinging closer to Hawaii than what was originally forecast.

We'll see an elongated fetch of severe-gale W/NW winds project through Hawaii's swell window with an embedded fetch of storm-force winds moving in on top of this large and active sea state.

What we'll see is the surf building rapidly through Wednesday to XL size, ahead of an XXL N/NW groundswell for Thursday morning, easing steadily through the day.

Size-wise, Pipe will be great Wednesday morning with clean 8ft+ surf groomed by easterly offshores, only shifting east-northeast into the afternoon as sets push towards 10-12ft+.

Come Thursday it'll be too big for Pipe and washing through from Third Reef but this should be great for Peahi, with 18-20ft surf, with the odd bigger cleanup set, easing off steadily through the day. However, winds are an issue, as they'll be fresh from the east in the morning, becoming strong through the day. This may be the limiting factor in green-lighting the event, though a decision is due soon.

Also it's worth noting the wave models are combining the existing XL swell with the new long-period energy and over-representing the size at a little.

Back on the North Shore, the wind will be moderate to fresh easterly, tending east-northeast trades with the XXL easing swell.

Friday is now looking more favourable regarding local winds across the North Shore as the swell continues to ease from 10ft+ out of the N/NW with strong east-northeast trades.

By the time the weekend comes around we'll be looking at smaller leftovers and lay days ahead of another large long-period NW groundswell due Tuesday next week. This will be followed by a similar-sized swell Thursday afternoon.

The source of these swells will be back to back lows spawning off the Kuril Islands, north-east of Japan, and at this stage we're looking at surf to 8ft+ with favourable winds, but we'll continue to follow this in the comments below.

North Shore 16-day Forecast Graph
North Shore WAMs