South-east Queensland and Northern NSW Surf Forecast by Ben Matson (issued Friday 28th May)

Features of the Forecast (tl;dr)

• Very large, windy S/SE swell this weekend, peaking later Sat, easing slowly Sun
• Large E'ly swell peaking later today, easing steadily through Sat
• Another large S/SE groundswell for Mon PM, easing Tues, with improving conditions
• Easing swells Wed/Thurs with light winds

Recap

Thursday saw wave heights persist around 4ft from the east, with a slight increase to 4-5ft through the afternoon that's held into this morning, ahead of another solid pulse of E'ly swell due to peak later this afternoon in the 5-6ft+ range. Winds were light north of the border early morning, but freshened from the south through the day; south of the border saw moderate to fresh SW thru' S/SW winds all day. Today we're seeing a broader W/SW flow across most regions with weak sea breezes developing in SE Qld. A S'ly change is pushing up the coast.

This weekend and next week (Jun 4 onwards)

There's no new news for the weekend outlook with no major changes to the synoptic charts, so there’s not much point detailing the obvious. Which is, fresh to strong southerly winds both days, and very large S’ly tending S/SE swells peaking Saturday then easing steadily from Sunday through Monday and into the middle of next week.

However, from a surf perspective there’s a few things the models aren’t picking up well and this will have a greater bearing on your choices over the coming days. So here’s my thoughts on how this event will evolve.

First of all, a renewal of long period E'ly swell is just starting to nose into the coast. And, there's some debate in the Swellnet office as to how much size we'll see. To be up front, I wasn't monitoring the early stages of the low that generated the large E'ly swell this week so I'm not fully in tune with the synoptics - and based on what I see, I'm expecting a peak around 5-6ft+ across exposed coasts later today, maybe holding into the early hours of Saturday morning though easing rapidly through the day.

This is also much higher than model forecasts are estimating. Our Gold Coast datapoint has a peak overnight tonight of 1.7m at 15.7 seconds, but this is in fact combining swell trains (later today, it's showing 1.1m @ 15.6 seconds, along with a primary mid-range E/SE swell of 1.6m @ 11.8 seconds - which disappears at midnight). And, our model-based surf estimate is for around 4ft, so my call for 5-6ft+ is a healthy percentage above that.

But.. Craig (love 'im!) is confident we'll see even more size, with a peak pushing 6-8ft at the swell magnets. We'll have to wait and see who'll win the big brass mug (FWIW, Swellnet developer Jono's prediction is that the swell will rise, but not as big or quickly as we're both predicting, and the buoy data will peak after dark, so nobody will be right and nobody will be wrong).

Anyway, it's all academic as fresh, gusty S'ly winds will confine the only options to sheltered points and protected southern ends.

The main questions are: will the E'ly swell be too big for some regions? And, how will it interact with the increasing S'ly swell, that's forecast to be even larger?

So, on to this S'ly swell. What a doozy.

We're already seeing S'ly swells push across the NSW coast today (biggest in Southern NSW), sourced from SW gales exiting eastern Bass Strait yesterday.

As the frontal sequence moves properly north-east of Tasmania today and the low develops to the east, we’ll see the resulting southerly fetch spread across the breadth of (almost) the entire Tasman Sea. This is a very impressive development.

However, at the peak of the first synoptic amplification, these southerly winds will be aimed towards New Caledonia - slightly off-axis for Northern NSW, even more so SE Qld. Because of the way this system is evolving, the sea state will consist of a broad spectrum of overlapping energies.

There’ll be a few secondary fronts racing around the primary Tasman Low throughout this period, and each will slightly enhance wave heights above usual size estimates, as they’ll have been working on an active pre-existing sea state generated by previous winds.

Swell energy from the south is expected to build all day Saturday, reaching a peak into the afternoon or overnight. South facing beaches south of Byron should reach a solid 12ft+ though it'll be totally unsurfable. Expect large surf almost everywhere, with a lot of water moving around and heavy sweeps. Saturday won't be a day for inexperience.

SE Qld will see much less size though even the semi-exposed points could become overpowered with the size of the swell and the sweep. The S'ly swell will be smaller earlier (though of course, we'll have a strong E'ly swell present), I'm expecting 5-6ft at these spots, pushing 6-8ft+ at exposed northern ends and south swell magnets. Protected inner points will be much smaller.

As for conditions, there’s a chance for early SW winds but only at a small number of locations, such as the southern Gold Coast.

Otherwise, the synoptic S/SW thru’ S’ly breeze will likely override most locations.

On Sunday, surf size will be very large at first, before temporarily easing thanks to the primary low weakening a little on Saturday afternoon. So, expect similar number as per above early morning, easing through the day.

Local conditions will be similar to Saturday though Sunday may see a slightly broader coverage of early lighter SW winds at a few more locations, for a little longer too.

Early next week

Late Sunday is where things get interesting.

On Saturday, a small secondary low is expected to form near the SW tip of New Zealand’s South Island, before slingshotting up along the western flank of the Tasman Low, with a new fetch of storm force S/SE winds (see below).

This fetch will generate the best round of swell of the entire cycle. The leading edge of this new pulse is expected to reach the Southern NSW Coast from very late Sunday, reaching the Mid North Cooast through Monday afternoon and Far Northern NSW late in the day.

The models aren’t really picking this up well, increasing swell periods (at Coffs Harbour) from 12.3 seconds early Monday to 13.2 seconds by lunchtime Monday, so our swell graph isn’t accurately reflecting what will eventuate - which is a kick in surf size back up to 8-10ft at south swell magnets south of Byron for Monday afternoon. I'm expecting this energy to be a little stronger than that seen over the weekend too.Of course, it'll be much smaller at locations with less southerly exposure.

Prior to then - i.e. early Monday - expect a further easing of size from Sunday, down to 6-8ft+ at south facing beaches south of Byron, 3-5ft across most SE Qld beaches and outer points, 6ft+ at south swell magnets.

Monday afternoon's pulse will arrive late north of the border but we should see the semi-exposed points pushing 4-6ft for the late session, and south swell magnets nudging 6-8ft.

Even better, swell direction will be more S/SE, which should allow for a broader spread of size across the region. We'll see moderating S'ly winds trending SW across more locations in the morning (than over the weekend) though exposed locations will still be wobbly and wind affected.

Although the responsible fetch will remain active through Sunday, it will gradually weaken into Monday and slowly rotate outside of our swell window, leading to a steady drop in surf size from Tuesday onwards. That being said, there’s a faint suggestion for yet another secondary front to wrap around the (weakening) Tasman Low on Monday morning, which may slightly arrest the easing trend on Tuesday.

So, let’s peg Tuesday morning around 6-8ft at south facing beaches south of the border (smaller elsewhere), 4-5ft across SE Qld points (6ft+ south swell magnets), easing by a couple of feet into Wednesday morning and then bottoming out in the 2-3ft range in Northern NSW on Thursday. The same size caveats apply for remaining beaches.

Conditions look excellent from Tuesday through Thursday with no synoptic influence and only weak sea breezes at best. So, banks pending, all of next week looks fantastic for surf.

Have a great weekend!