Mixed bag of swell sources this week

Ben Matson picture
Ben Matson (thermalben)

Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Monday 15th December)

Best Days: Early Wed: Fun but easing, inconsistent E'ly swell, with S'ly winds. Should be some NE windswell in the mix too. Late Thurs/early Fri: another slightly stronger E'ly swell, with NE winds Thurs tending fresh S'ly Fri. 

Recap: The weekend came in very close to forecast - large, bumpy waves Saturday with fresh but easing onshore winds, and slightly smaller but still punchy and much cleaner waves on Sunday thanks to an early offshore breeze. Wave heights have trended down slowly today as well, with early light N’ly winds swinging NE and freshening this afternoon.

Next week (Dec 16th - 19th)

We’ve got another complex but ultimately rewarding week of waves ahead, if you can work around a few windows of opportunity here and there.

The current swell will continue to ease slowly through Tuesday, and freshening NE winds will generally deteriorate conditions at most beaches (there’s only a slim chance at best of a temporary light N’ly breeze at dawn). Wave heights should manage an inconsistent 2ft+ at open beaches with reasonably long waits between the sets. Not really worth the effort but you will be able to get wet.

Late afternoon, we’ll see a new pulse of long range E’ly swell that should provide some bigger waves in the few hours before dusk, possibly up around 3ft - however it may not really be distinguishable from both the existing mid-range E/SE energy and the addition of a peaky NE windswell on top (that may also reach 2-3ft at NE facing beaches late).

This swell will have been generated by a stationary E/SE fetch that set up camp off the West Coast of New Zealand’s North Island on Sunday - in fact it’s the remnants of last week’s impressive Tasman Low which generated our sizeable weekend swell.

Both the east swell and north-east windswell should hold into Wednesday morning with inconsistent 2-3ft sets at exposed NE facing beaches. Additionally, a gusty southerly change is expected to arrive in the early hours of the morning, so there should be fun clean options inside sheltered southern corners. We’ll see a bumpy southerly windswell build throughout the day with 3ft+ sets at south facing beaches by the afternoon (smaller earlier), but there won’t be much quality at these locations.

Expect easing surf from the E’ly and NE swells during the day (i.e. aim for a morning session for the best waves), and winds will probably ease and tend SE later in the day.

Thursday will then see a return to a NE airstream and mainly small residual swells from the south and east, somewhere in the 2ft+ range at exposed beaches. 

Late afternoon will herald the arrival of yet another pulse of E/SE swell from the fetch off New Zealand’s North Island. In fact, it’s expected to become briefly super-charged on Tuesday afternoon as a weak tropical low - that formed off the Central Qld coast over the weekend (but is not actually a swell producing system) - travels SE through the trough line across the Northern Tasman Sea, and merges with the primary fetch.

This is modelled to spin up a fresh E’ly fetch aimed a little further south than the current system, with wind speeds in the 30-40kt range (see image below). An arrival is pegged for the NSW coast very late in the day (probably after 4pm) and sets should approach 3-4ft+ right on dusk at times. Our surf model isn’t picking this up very well right now but should correct itself over the coming days.

My main concern with this swell related to (1) Thursday afternoon’s nor’easters, which could reach 20kts at the same time the swell arrives (thanks to an advancing southerly change on the Far South Coast), and (2) this swell is expected to peak overnight so there may be only a brief window of good waves early Friday morning as surf size begins to throttle down.

We should see early 3-4ft sets but this particular swell is expected to ease a little more rapidly than the Tues/Wed swell, due to the shifting fetch alignment (from east to north-east) as it develops. So it could be down to 2-3ft by late morning and possibly even smaller by late afternoon.

So, Friday morning should offer good waves in southern corners again, due to the protection they’ll offer from the initially gusty southerly breeze. This change should once again whip up 3ft or so of peaky surf at south facing beaches by the afternoon, and local winds should abate throughout the day, creating lumpy surf for the late session at exposed locations.

Let’s check back in on Wednesday to see how the Tues/Wed E’ly swell performed, and how the Thurs/Fri is tracking.

This weekend (Dec 20th - 21st)

Nothing of major interest this weekend - looks like we’ll mainly see a mix of small leftover S’ly swell from Friday’s pulse, and some minor background E’ly energy - just a cople of feet max at open beaches. Hopefully Wednesday will see some changes in the models towards a more active period! But right now it looks like swell magnets only.

Long term (Dec 22nd onwards)

Broad trades developing north and north-east of New Zealand from this weekend signal a return to small but long-lasting distant E’ly swell for the foreseeable future (beginning early-mid next week, that is).

Elsewhere, we’re looking at freshening NE winds through Sunday that may whip up a local windswell for Monday, and a possible southerly change shortly behind that.

One other region that's also going to be on my monitor for the longer term is the Northern Tasman Sea, which is showing signs of troughiness throughout the longer term models runs. This could very well be the source of a better quality NE swell mid-late next week for southern NSW. Check back in on Wednesday for more details.


thermalben's picture
thermalben's picture
thermalben Monday, 15 Dec 2014 at 8:27pm

Sorry it's late everyone. Had one of those days!

oiley's picture
oiley's picture
oiley Tuesday, 16 Dec 2014 at 2:34pm

any idea whether the late THurs swell is likely to hit the south coast any earlier?

thermalben's picture
thermalben's picture
thermalben Tuesday, 16 Dec 2014 at 2:42pm

Wouldn't bet the house on it. WIll have a better idea tomorrow though.

pensky's picture
pensky's picture
pensky Tuesday, 16 Dec 2014 at 11:37pm

Hi Ben and experienced south coasters

At risk of being perceived as an annoying blow-in....I'm visiting family in Canberra this week and have convinced them to go to sth coast for a bit. Ive researched as much as possible but just wondering if anyone can give me some local feedback on likely conditions expected for the southerly swell/wind on Friday? Its only me and son and I've been out of water for ages so I'm going to be cruising anyway. Is the swell going to big enough for the protected points like Pink rocks (broulee), moruya river mouth? Or even saltwater (I'm keen to show my son the national park but won't worry about the drive if its not really going to be breaking). Any insights greatly appreciated.