Swell pans out across the Pacific

Craig Brokensha
Swellnet Analysis

If you watch how swells are produced around the world you'll notice patterns forming.

Storms and swells usually develop in similar regions, season after season, year after year. Whether they're linked to climate drivers, the arrangement of the continents, or the general storm track around the globe, swells arrive from reliable directions at certain times of the year.

However, sometimes less common synoptic setups occur, and it's these rarer setups that pique the interest of forecasters.

One such weather pattern is starting to develop south of New Zealand.

The Long Wave Trough which influences the placement and intensity of the westerly storm track usually strengthens either side of New Zealand. When it's to the west, the Australian East Coast and Fiji receive southerly swell energy passing up through the Tasman Sea, and when it's to the east, Tahiti and the Pacific Islands come under direct fire.

What we'll see over the coming 48 hours though is a node of the Long Wave Trough strengthening right over New Zealand, moving slowly east through the weekend.

Under this setup, we'll see a vigorous polar low generating swell fanning out from below New Zealand, splitting both west and east into the Tasman Sea and Pacific Ocean concurrently.

A broad fetch of 35-45kt southerly winds will initially be projected up through Australia's swell window before tending more south-southwest and into Tahiti's swell window.

The result will be a great long-period groundswell hitting the Australian East Coast (arriving across Tasmania Sunday afternoon) and peaking further north early next week. The Solomon Islands and Papua New Guinea should see the swell arriving mid-week while Fiji will actually be shadowed by New Zealand in this instance (though seeing solid surf from a strong front just before the low forms).

Tahiti will see a large and powerful south-west groundswell arriving mid-week, building through Tuesday and peaking Wednesday in the 8-10ft+ range. Conditions look excellent with east-northeast offshores due at the peak of the swell. Tonga and Samoa will also see large surf through Tuesday and Wednesday next week, with the swell eventually filtering up to Hawaii's southern shores, Mexico and California.

New Zealand will also receive large surf across it's east and west coasts as well as swell as snow across most of its peaks. With the amount of wind though, the best waves will be found in more protected spots.

Comments

Beagle's picture
Beagle's picture
Beagle commented Thursday, 18 May 2017 at 1:44pm

Out of interest - does this mean the best swells for Tonga are Chopes swells rather than Cloudbreak swells (i.e. fronts racing up NZ's south-west coast)? I'm going to be spending a lot of time there in the next three years for wife's work, so it would be good to know!

Craig's picture
Craig's picture
Craig commented Thursday, 18 May 2017 at 1:47pm

Not necessarily. If a strong cold front pushes up through the Tasman Sea between Aus and NZ, this is ideal, while if the fronts passing east of New Zealand don't actually project north then Tonga won't see too much size.

You can see this when looking at a map of the region.

thermalben's picture
thermalben's picture
thermalben commented Thursday, 18 May 2017 at 2:04pm

Also.. Tonga's best waves are on NW tip so Tasman swells are the best (not sure if South Pacific swells work properly there, even if very large). Tonga also picks up north swells too.

Beagle's picture
Beagle's picture
Beagle commented Thursday, 18 May 2017 at 2:18pm

Thanks Ben and Craig. That makes sense. Can't wait to take the 4WD/boat for an explore - I might even report back :)

It's a pity Tongatapu's south coast seems to be comprised of sheer drop-offs, death-keg cliff closeouts and blow holes...it seems completely exposed to swell with good prevailing winds :/

mibs-oner's picture
mibs-oner's picture
mibs-oner commented Sunday, 21 May 2017 at 8:10pm

There's spots to the south on a different island. Take your boat and get some bazzas

Mibs

mick-free's picture
mick-free's picture
mick-free commented Thursday, 18 May 2017 at 2:03pm

meanwhile in NZ havoc from 10m swells and 70 kilometre hour winds....

Mick Free FIFOFOMO

Island Bay's picture
Island Bay's picture
Island Bay commented Monday, 22 May 2017 at 2:39pm

Surfed a NNE-facing spot inside Wellington Harbour at the peak of the swell yesterday. And yes, the winds were about 70km/h and the temp 7C.

freeride76's picture
freeride76's picture
freeride76 commented Thursday, 18 May 2017 at 2:13pm

I'm pretty sceptical about this system as a swell source for the east coast....I know it's part of the swell window, but the system really needs to stand and deliver......seems to race off pretty quickly.
Very happy to be proven wrong though.....it's a beautiful angle for here.

Craig's picture
Craig's picture
Craig commented Thursday, 18 May 2017 at 2:15pm

The short-lived ones yes, but this is broad, expansive, moving over an active sea state produced by the strong front before it, and lasting almost 24 hours in our swell window. I likey.

freeride76's picture
freeride76's picture
freeride76 commented Thursday, 18 May 2017 at 2:16pm

yeah, the initial stages looking pretty tasty on current ASCAT passes.

Chris Buykx's picture
Chris Buykx's picture
Chris Buykx commented Thursday, 18 May 2017 at 8:57pm

Ok! -this swell has now got my attention. 1.5m - 1.8m SSE at 15 sec!! Roughly translates to........

memlasurf's picture
memlasurf's picture
memlasurf commented Thursday, 18 May 2017 at 9:19pm

Craig does this have any effect on Victorias waves to the east and far east? Always wondered if these events can beat the strong west push we always have here.

Craig's picture
Craig's picture
Craig commented Thursday, 18 May 2017 at 10:49pm

Yeah Shaun's region, the Gippsland coast will have waves.

belly's picture
belly's picture
belly commented Friday, 19 May 2017 at 12:23pm

Shaun the sheep? Best show on ABC2, closely followed by Go Jetters and Thomas :)

memlasurf's picture
memlasurf's picture
memlasurf commented Friday, 19 May 2017 at 12:26pm

Yep a real fan of that one as well and Thomas the Tank is a legend.

freddieffer's picture
freddieffer's picture
freddieffer commented Friday, 19 May 2017 at 1:22pm

Don't forget Bernard. He's a classic. Very sharp and funny.

Tim Bonython's picture
Tim Bonython's picture
Tim Bonython commented Saturday, 20 May 2017 at 9:18am

Lets not talk about Teahupo'o.

Coastal's picture
Coastal's picture
Coastal commented Sunday, 21 May 2017 at 10:38am

19.4-metre wave captured by a newly-deployed buoy in the Southern Ocean on Saturday morning.

www.stuff.co.nz/environment/92809604/oh-buoy-southern-hemispheres-larges...

Craig's picture
Craig's picture
Craig commented Monday, 22 May 2017 at 10:23am

Just for a record of the event, peak periods of 17-18s off Sydney with large pumping, though inconsistent surf across southern NSW.