Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Friday 3rd June)

Best Days: Sunday: Hellman options as the winds swing to the W/NW. Monday: Hellman options (Round 2) at exposed spots. Tues/Wed/Thurs: very solid and clean almost everywhere, though slowly easing. 

Recap: Building SE across the region on Thursday (favouring northern coasts such as the Sydney/Hunter regions), reaching 3ft+, before easing slowly today. Generally light winds both days. 

This weekend (Saturday 4th - Sunday 5th)

It’s one heck of a synoptic chart. 

I encourage you to cycle through the South Pacific WAMS (clicky here), and take note of the size and strength of the New Zealand high pressure system, because it’s the primary driving force behind this upcoming swell event. 

Obviously, there’s another crucial ingredient - the developing trough off the East Coast, with several embedded low pressure centres expected to form along the trough line, which will display enhanced wind speeds - but it’s the stubborn high pressure system that’s forming a block, allowing the north-east squeeze to reach such an impressive length, width and strength. 

Nevertheless, we have a weekend of two halves ahead. 

And in all honesty, the best surf from this developing system won’t occur this weekend - so pace yourself and be prepared for quite a few days of very solid surf next week. 

Saturday will be characterised by strengthening NE winds and building NE swells. We’ll be starting from a pretty small base, as the synoptic flow isn’t really expected to develop much strength overnight however we will see a close relationship between the two; that is, there won’t be much of a lag time between the strengthening airstream and the onset of building swells.

It’s hard to put a total on Saturday’s surf size, because we’re looking at a steady upwards trend through Saturday and all day Sunday too. So as an estimate it’s quite plausible for late afternoon to see 6-8ft+ bombs at exposed spots even though it’ll be mainly short range storm surf. 

Sunday is where things get really interesting. As the coastal trough pushes south, we’ll see winds tend variable before a westerly outflow extends across the coastal margin. 

The timing on this is crucial as we’ll need at least a few hours for surface conditions to clean up. Right now, model data has this occurring later Sunday morning the Sydney and Hunter coasts - indeed, the BOM currently expect winds to shift N/NW "in the early afternoon” across Sydney, but I have a feeling it’ll develop sooner than this - sometime overnight on Saturday (though, this will be delayed across locations south of Sydney, probably around dawn across the Illawarra and later further south). And I think we’ll see more W/NW in the airstream too. 

The NE fetch developing across the Tasman Sea will initially be aimed into the Sydney region but as the trough slides south, so will the alignment of the fetch (towards the South Coast, then the Far South Coast and eventually Tasmania’s East Coast). 

So, Sunday’s surf will consist of short range NE swell from the primary fetch plus better quality E/NE swell from the back of the fetch that will spread back into the mainland. Essentially, we’ll see a combination of easing swell heights but growing periods - the latter looks like it’ll be more influential than the former, which means surf size should continue to build throughout the day, reaching 10-12ft+ across exposed Hunter/Sydney and Illawarra coasts throughout the day. 

Bigger surf is likely across the South Coast though we may not see a peak down here until Monday. And the local NE fetch will persist through a greater percentage of the morning so it’ll take a lot longer to clean up anyway. 

So in short - we’re looking at very large swells continuing to build all day Sunday, with a steady improvement in surface conditions as the W/NW fetch develops across the coast.

Next week (Monday 6th onwards)

One of the most impressive aspects of this system is the extent of the NE fetch back out into the north-eastern Tasman Sea, and the small embedded lows along the trough line. This fetch is expected to reach back into Fijian longitudes, possibly even further east later next week, though it’ll be smaller in spatial coverage by this time and will be a long way from the mainland.

The small embedded lows will contribute further strong pulses of E/NE tending E’ly swell from Monday through Thursday. Their fetches will be working on a very active sea state (generated by the days of NE winds prior), which will enhance the expected swell heights and periods from what would be expected from an otherwise solitary system.

But the broader trough will be tracking south, slowly outside of our swell window which means as we progress through the week we’ll be seeing a greater percentage of swell spread and distant energy form the back of the fetch.

As such, and as mentioned above for Sunday, we’re looking at easing swell heights but growing swell periods through the first half of next week, of which I think the benefits of the latter will outweigh the negatives of the former. Essentially, there’ll be a couple of E/NE swells in the water - our model has the primary swell at in the mid-11 second range Monday and Tuesday, with a smaller but stronger swell in the mid-14 second range. 

This pattern should maintain much larger surf than is currently modelled. Monday is likely to see a couple of pulses during the day, with peak wave heights across exposed Sydney/Hunter/Illawarra breaks around 10ft+ (larger across the South Coast), easing to 6-8ft on Tuesday and then 5-6ft on Wednesday. Smaller surf is then expected through Thursday and Friday.

This is just a broad overview for now, as future model runs are likely to alter these projections over the coming days - and once satellite data becomes available we should be able to better identify individual pulses throughout the extended forecast period. 

Winds are looking really good throughout this period; a small low is expected to develop off the Far South Coast on Tuesday, and we’ll see fresh W/NW thru’ W/SW winds Monday and Tuesday, easing to a light W/NW on Wednesday before possibly tending N’ly later as a front approaches from the west. NW winds are then due Thursday before W/SW winds redevelop in association with a passing front and low to the south on Friday. 

Although the broader Tasman trough will continue to retreat south then east throughout the week, models are still expecting an active fetch north and north-east of New Zealand on Wednesday, Thursday and Friday which could very well maintain fun but very inconsistent 3-4ft surf across exposed beaches into next weekend. But that's a long time away and we have more important issues at hand in the interim. 

Other than this, we’re looking at a strong series of fronts south of Tasmania from Thursday that should kick up some new S’ly swell from Friday onwards (early ballpark 4ft south facing beaches). 

So that’s it for now..  it’s definitely one of the more interesting weather patterns in recent memories, and I can’t wait to see what unfold. Have a great weekend!