Complex mix of swells from the south and north-east

Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Wednesday 16th September)

Best Days: Plenty of south swell for the entire period though wind affected most days. Peaky NE windswell in the mix most days too. 

Recap: Ahh, flukey south swells. We’ve had size reports anywhere from 1-2ft up to 4-5ft throughout Southern NSW over the last 36 hours, and winds have been up from the east through north, creating less than ideal conditions (though this morning did have a window of light breezes). As expected it’s been inconsistent, random, lully, and overall we’re probably seeing a little size than anticipated.

Late Wednesday arvo southerly lines in Newy

This week (Sep 17 - 18)

Actually, we have four, almost five more days of flukey long period southerly swell on the way. 

The current energy - and that expected on Thursday - is from a strong frontal progression below the continent over the weekend and earlier this week. The longest swell periods in that sequence will arrive tomorrow (17 seconds) but it’s sourced from a poorly aligned fetch so I’m going to keep wave height estimated broadly inline with Monday’s notes, and that is with inconsistent 3-4ft sets at south facing beaches, occasionally between 4ft to maybe 6ft across the Hunter (and offshore bombies/other reliable south swell magnets). Of course, surf size will be much smaller elsewhere at beaches not open to the south. Size likely to ease through the day too.

And, please allow me to repeat the caveats from Monday’s notes: most south swells typically favour a certain number of breaks, but Thursday’s energy will reduce this by about half due to the flukey, remote, poorly aligned swell source. This is not a high confidence swell event so peg your expectations appropriately. 

We’ll also see some small NE windswell in the water from today’s developing fetch off the coast (maybe some rare 2ft+ sets at NE swell magnets), but conditions should clean up quickly with light NW winds for most of the day, possibly tending N’ly into the afternoon ahead of a southerly buster rocketing in to the South Coast after lunch, reaching the Illawarra mid-afternoon and Sydney around dinnertime (would be nice to see a shelf cloud!).

So, the morning will have the best combo of size potential and local winds though it may still be slightly lumpy.

A trough associated with the change will then stall off the Northern NSW coast on Friday, maintaining moderate E’ly winds across much of Southern NSW though it won’t be strong so pockets of light/variable winds are possible (though the Cenny Coast and Hunter region may see lingering moderate to fresh SE breezes very early).

Easing S’ly groundswells on Friday will be accompanied by an increase in temporary short range S/SE tending E/SE swell (thanks to the change) though I don’t think there’ll be much more than 2-3ft at south facing beaches from either source (maybe another foot or two of longer period energy across the Hunter early morning). 

Both days should also see a small undercurrent of trade swell, though no major size is expected. 

This weekend (Sep 19 - 20)

The weekend looks really interesting, from a synoptic perspective.

A stationary, burgeoning high in the Tasman Sea will strengthen northerly winds along the NSW coast, increasing NE swells through Saturday and Sunday ahead of a peak on Monday. Saturday should see 2ft surf increasing to 3ft and Sunday’s likely to hold in the 3-4ft range all day, though conditions won’t be great as the N/NE breeze picks up in strength,

At the same time, another long period S’ly groundswell will dominate the region, generated by a broad, distant W’ly fetch at polar latitudes, well below the continent today (see below, from our Vicco WAMS).

Set waves will be very inconsistent from this source but peak swell periods should reach somewhere in the 16 second range, and an associated upwards trend through Saturday should create 3-4ft sets at south facing beaches late afternoon and early Sunday (easing through the day). Reliable south swell magnets such as the Hunter could see occasional 4-5ft, maybe 4-6ft bombs though it’ll be extremely inconsistent.

Of course, with moderate to fresh N/NE winds there won’t be many surfable options on hand. Early Saturday morning will probably have the lightest winds of the weekend (still onshore, mind) but the smallest surf size overall.

Let’s fine tune things in Friday’s update. 

Next week (Sep 21 onwards)

NE swells from the stationary Tasman high should peak on Monday around 3-5ft at NE facing beaches, and the weekend’s southerly swells will ease back very quickly. However conditions look to be average at best with continuing northerly winds.

A W'ly change will then push off the coast on Tuesday, improving conditions rapidly as the NE swell steadily eases, though early 3-4ft sets are still likely through the morning. 

The second half of the week has a southerly swell on the cards sources from a cut-off low advancing across the eastern states. 

More on this on Friday. See you then!


mick-free's picture
mick-free's picture
mick-free commented Wednesday, 16 Sep 2020 at 7:05pm

Cut off low oh yeah


thermalben's picture
thermalben's picture
thermalben commented Wednesday, 16 Sep 2020 at 7:28pm

What excites ya about the COL?

niclong's picture
niclong's picture
niclong commented Wednesday, 16 Sep 2020 at 8:13pm

What is a cut off low, Ben? You mention them a fair bit.