UPDATE: Friday January 15: The storm is currently about 2,500 miles northwest of Hawaii, with an area of storm-force winds persisting on its southwest flank. The fetch has already generated open-ocean wave heights of over 40 feet, and the swell forecasted to arrive on Saturday is now unstoppable.
Over the next 24 hours the low is expected to initially continue towards the east-southeast, then arc around towards the northeast, before weakening. The intensity of the windfield peaked slightly earlier and the storm is expected to arc around quicker than originally forecast, so the swell arriving in Hawaii is now expected to be slightly smaller and shorter lived. But it will still be humungous.
At Peahi, super-long period forerunners of over 25 secs are expected to arrive overnight Friday-Saturday, with the swell filling in and peaking around the middle of the day. Conditions will be, let’s say, challenging, with wave heights over 30 feet, some short-period cross-swell and moderate to fresh winds from an easterly quarter.
EARLIER: The North Pacific has been singing the past few weeks. From December 29, all the way through to today (with another session at Mav's about to throw down), it has been non stop action. But we could be in for a crescendo like we haven't seen before. Come Saturday, Maui's stunning XL wave Jaws could go into loco territory -- because looking at the forecast right now, it's could be the biggest day we've seen in years.
We're talking well beyond the realms of mere mortals. This is one for the hellmen and women of our humble community. But what kind of numbers are we dealing with here? It could look similar to this time, almost five years ago to the day, when Aaron Gold paddled the biggest wave, possibly ever, out at Peahi -- on January 15 2016.
"Yesterday [Jan 12], a low started to form off Japan and move out into the open ocean towards the northeast," said MSW forecaster Tony Butt. "As of today, Wednesday, the system has already deepened considerably, and is currently located south of the Aleutian Islands. There is an area of storm-force north-westerly winds on its southwest flank, starting to generate some large swell.
"The upper airstream shows a strong north-south pressure gradient and a strong, meanderless jetstream on the western side of the North Pacific, which is pumping energy into this system. In contrast to a recent system that deepened on the eastern side of the North Pacific (and produced a large swell at Maverick's), the present system is expected to explode before it gets half way across.
"Tomorrow, Thursday, will be crucial for sending a massive, long-period swell towards Hawaii, as the system and its windfield tracks east-southeast in the same direction as the swell it is producing (dynamic fetch, again). By early Friday, open-ocean wave heights northwest of the Islands are expected to be well over 40 feet. The storm then arcs around to the northeast and gradually weakens as it tracks towards Canada.
"The swell begins to arrive in Hawaii overnight Friday-Saturday, with forerunners of over 25 secs period. By Saturday morning the swell is expected to have already filled in, with periods of around 20 secs and humungous wave heights at swell magnets such as Jaws. Here, the bathymetric focusing means that breaking wave heights could be well over 30 feet – around twice those in deep water.
"At Peahi the swell will arrive fairly clean with a minimum of interference from secondary shorter-period swells. Expect moderate to fresh winds from an easterly quarter, picking up in the afternoon and making things lumpy."