Late last week the first significant storm for 2019 was progged to develop in the North Pacific Ocean, with the likelihood of an XXL swell event for this coming weekend.

Early this week, however, the global forecast models backed off the intensity and scope of the storm, and a downgrade was made in the North Pacific Forecaster Notes to a lesser 15-20ft.

Fortunately for big wave surfers the downgrade was an anomaly. The models each reverted back in favour of the storm and held true through a series of models runs, so we're now set to see a significant long-period NW groundswell impacting the Hawaiian Islands.

The storm formed east of Japan and it's currently bombing with its central pressure dropping from 988hPa down to an incredible 933hPa in a 24 hour period. That's a drop of 55hP, well over the required 24hPa to classify it as a weather bomb.

With such a rapid drop in central pressure we'll see core wind speeds reach hurricane-force, that being 70-75kt (129 – 139km/h).

These hurricane-force winds - which are supported by surrounding severe-gale to storm-force winds - will be aimed towards Hawaii for nearly 24 hours, generating long-period forerunners that will register on the Hawaiian buoys in the order of 24-25 seconds with the bulk of the groundswell arriving not too far behind and falling between 17-18 seconds.

For comparison, it looks very similar in size, if not a touch bigger, to the swell seen through the Jaws Challenege event where they had to postpone the contest after one heat. It is a couple of degrees more west in direction as well resulting in heavily bowling waves on Peahi's inside reef.

Timing wise, the swell is forecast to arrive across the North Shore mid-morning Saturday, building rapidly and dramatically to 20-25ft at the marquee big wave breaks and outer reefs by late in the day, with Peahi seeing the swell arriving a few hours later, kicking XXL through the afternoon and evening.

Unfortunately, a peak is likely overnight, with similar if not slightly smaller surf easing slowly through Sunday. Winds on the North Shore look excellent with weak east-southeast trades, while Peahi will see strong afternoon easterly trades, more favourable and weaker out of the east-southeast each morning.

This swell should meet the thresholds required to run the In Memory of Eddie Aikau contest at Waimea, but there's been no word from the event organisers regarding yellow-lighting the event.

The Da Hui Backdoor shootout is also on standby, but the weekend will max out while Monday could be excellent as the swell eases back down to 10-12ft range. Still at the upper size limit for Backdoor but it will keep easing through the day.  The wind will be light easterly trades.

The rest of the week will provide oversized backup NW groundswells through Tuesday and Wednesday with great conditions ahead of Kona (S'ly winds) winds developing on Wednesday.

North Shore Forecast Graph
North Shore WAMs