thermalben

Extended run of southerly swells for Southern NSW

Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Monday 6th April)

Best Days: Tues/Wed (peaking early Wed): fun S'ly swells, generally good winds. Size easing Thurs. Sat/Sun: strong S'ly swells, generally good winds. Early next week: more S'ly swells. 

Recap: The weekend delivered small but fun E/NE swells both days with inconsistent 2-3ft sets across open beaches Saturday, easing slowly through Sunday. A small NE swell was also in the mix on Saturday though showing best south from Sydney. We also saw a minor S’ly swell into Sunday afternoon, with 1-2ft sets at south facing beaches. Wave heights have remained small today with mainly background E/NE swell holding 1-2ft sets. A brief northerly flow easterly Saturday gave way to otherwise sparkling clean conditions with winds for the west thru’ north-west.

Residual E/NE swell in Newcastle this morning

This week (Apr 7 - 10)

We’ve got a couple of southerly swells due over the coming days as a strong long wave trough tracks across Tasman Sea longitudes. 

Initially, the early energy will be generated by weaker and/or less favourably aligned winds exiting eastern Bass Strait, and also along the Southern NSW coast. However the parent low - positioned well to the south of Tasmania this morning - is showing a decent fetch of 40-45kts winds, and will today track north-east through our south swell window, generating a larger pulse that’ll provide the biggest waves of the week.

Tuesday will generally see small southerly swells though it should trend up slowly through the day, perhaps early 2-3ft+ sets at south facing beaches (smaller elsewhere, but bigger across the Hunter) with some larger sets starting to show into the afternoon.

The strong pulse from the parent low will push across the Far South Coast mid-late afternoon, reaching the Illawarra probably after dark and therefore pushing across Sydney and Hunter Coasts overnight. 

This should provide strong 4-5ft waves to south facing beaches Wednesday morning (larger 5-6ft sets across the Hunter/Newcastle stretch) but as per usual it’ll be much smaller at beaches not open to the south. Expect a slow easing trend into the afternoon and a more steady drop in size through Thursday.

Both Tuesday and Wednesday will also see a small underlying signal of slow E/NE swell in the 1-2ft range, originating from the ridge supporting TC Harold, currently devastating Vanuatu.

Tuesday's local conditions are still at risk of a lingering southerly breeze though this is most likely north from Sydney through the Hunter in the morning, and should ease throughout the day anyway - light variable winds are expected in most regions after lunch.

Wednesday’s peak in size will be accompanied by light and variable winds through the morning, but a weak trough off the coast may push ashore during the day, freshening south-easterly winds into the afternoon. I don’t think we’ll see a lot of strength but this is certainly a risk.

Looking elsewhere, and TC Harold won’t directly generate any swell for us. It’s currently inside the New Caledonian swell shadow, and once it clears this region it’ll accelerate to the east towards the South Pacific, too fast to generate swell for the Australian East Coast. 

Over the last week or so I’ve been mentioning a deep trough/tropical low well to the east, inside the NZ swell shadow that had some peripheral potential. Over the last few days the models have ever so slightly shunted this system to the south, to the point where I can be a little more confident in ruling out swell prospects from it. Some locations in SE Qld may pick up waves later this week and through the weekend, but I’m now doubtful of anything materialising in Southern NSW.

Therefore, Friday looks small for the most part. A series of overlapping southerly swells associated with another amplifying node of the Long Wave Trough are expected this weekend and the first may make landfall at some point on Friday - but more likely the South Coast than anywhere else. Let’s take a closer look on Wednesday and see if it has any potential for Sydney, Hunter and Illawarra coasts.

This weekend (Apr 11 - 12)

The models have changed the structure of the LWT due to push south of Tasmania later this week. 

In fact, there’s still a bit of divergence between the models so the specifics aren’t yet clear, but the general trend is for the main low in the sequence to display very strong winds south of Tasmania early Friday (see below), resulting in a Saturday afternoon or early Sunday peak in size across Southern NSW. 

This output (via GFS) shows incredibly strong winds aimed away from our swell window, but the resulting spread of energy would still kick up a large swell event somewhere north of 6ft to maybe 8ft at reliable south swell magnets - however the flukey swell source would result in a wide range in size across the region.

Current indications are for good winds too, offshore though perhaps fresh at times.

This is all still quite some time away so let’s take a closer look on Wednesday, as the models should start to consolidate towards a common position by then.

Next week (Apr 13 onwards)

Powerful secondary fronts trailing behind the system responsible for the weekend’s south swell should maintain strong southerly swells through the first half of next week, though the poor fetch alignment will keep a lid on anything overly sizeable.

That’s the main focus of the long term charts. We’ll firm up things in more details on Wednesday. 

See you then!

Comments

mibs-oner's picture
mibs-oner's picture
mibs-oner commented Monday, 6 Apr 2020 at 5:59pm

Right in time for overcrowding leading to beach closures!!

epictard's picture
epictard's picture
epictard commented Monday, 6 Apr 2020 at 8:53pm

Nah, once it's over 4ft on the East coast most of the crowd vanishes into the mist.

black-duck's picture
black-duck's picture
black-duck commented Monday, 6 Apr 2020 at 9:24pm

i would disagree with that epictard. in fact, it seems to me to be just the opposite. 4ft plus seems to bring out more numbers, way more in fact, not less. 6ft and over i would start to agree, as it limit choices anyway, but 4ft plus is a magnet. It would be the most crowded in the places i surf in that range, without a doubt. Super crowds in fact.

epictard's picture
epictard's picture
epictard commented Monday, 6 Apr 2020 at 10:14pm

Pity for you Duck.

I grew up in the middle of Sydney where in the last couple of decades it has been absolutely true in my experience. I have had plenty of surfs, uncountable, at 5ft+ with one or two mates at beaches in Sydney where the next day is 1-2ft and there is a cast of hundreds.
Yeah, 6ft+ draws a totally different crowd ... not sure where you are located (nice brewery suiting your name up the coast) but fortunately I am spoiled for choice at any size that I can handle now that I live out of Sydney and the numbers are low at all times.

marcus's picture
marcus's picture
marcus commented Tuesday, 7 Apr 2020 at 9:12am

newcastle is saying dangerous surf conditions already. ;)
watch out for those undertows boys

i remember the internet when it was just for intelligent people but.

jordan.mar's picture
jordan.mar's picture
jordan.mar commented Tuesday, 7 Apr 2020 at 3:05pm

Hey Ben, would it be wishful thinking for a mid to long period NE- Easterly swell from that cyclone tracking from vanuatu? Surely we would get some sort of energy from it?? Looks like there is a brief period where it passes inbetween the New Caledonia Swell shadow and the new zealand shadow, I saw the secondary swell your model predicted but thought there would be more energy and would be later towards friday??

TheBoogieMar

geoffrey's picture
geoffrey's picture
geoffrey commented Wednesday, 8 Apr 2020 at 5:36pm

There was definitely a little cyclone swell today. Inconsistent and small but it was definitely from the E/Ne

thermalben's picture
thermalben's picture
thermalben commented Wednesday, 8 Apr 2020 at 6:04pm

Eh? Impossible. TC Harold only just pushed out of the New Cal swell shadow today. 

thermalben's picture
thermalben's picture
thermalben commented Wednesday, 8 Apr 2020 at 6:05pm

All covered in the latest Forecaster Notes.