Large, windy S'ly swell late Wednesday and Thursday

Ben Matson picture
Ben Matson (thermalben)

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

Best Days: Tues: only small but nice and clean. Wed: large late pulse of new S'ly swell (but windy). Thurs: very large, windy S'ly tending S/SE swell, best suited to protected corners. Fri: moderating S/SE swell and S'ly winds (maybe SW early), best suited to protected corners. 

Recap: Poor surf Saturday with gusty onshore winds and a solid combo of E/SE and S’ly swells around 3-5ft. Significant improvement on Sunday with light offshores and a pumping combo of SE and E/NE swells, anywhere between 3ft and occ 4ft. Surf size dropped again this morning (2ft at most open beaches) but reports have filtered through of a few stray 2-3ft sets at times throughout the day. Generally good winds too. 

This week (Apr 7 - 10)

Nothing major on the cards for Tuesday. We’ll see a small level of swell from two sources - some inconsistent E/NE energy originating from a minor trade flow north of New Zealand early in the Easter break, and a small NE windswell from a brief fetch expected to develop in our immediate swell window tonight.

No major size is expected from either source (occ 1-2ft sets) but with winds expected to swing NW early morning and freshen, there’ll be a few fun beaches around if you’ve got a high volume board and plenty of patience.

Wednesday will be a day of dynamics on the synoptic front. As discussed last week, we’re expecting a deep cut off low to form rapidly off the South Coast early in the day, and as this happens, gale to storm force southerly winds will develop parallel to the southern NSW coast. 

Prior to this happening, we’ll see strengthening W/NW winds across the region with very small residual E/NE swell across the region (nothing to get excited about), however the developing southerly fetch will generate a large southerly swell, and due to the proximity of the fetch to the mainland, we should see a very quick translation to new surf at the coast. 

Estimating a precise upwards trend is a little tricky. At this stage I doubt we’ll see see much new energy before late morning, but from lunchtime onwards we’re likely to see an initially steady, then rapid increase in surf size with SW winds maintaining gale force strength through the afternoon (even stronger on the South Coast, and more S/SW in direction).

So, by early afternoon south facing beaches should be in the 3ft range, by mid-late afternoon it’ll probably be close to 4-6ft and by the end of the day, exposed swell magnets should be pulling in 6-8ft+ bombs. 

However with these gusty SW winds, you’ll really need to tuck into sheltered location - and wave heights will be considerably smaller with decreasing southerly exposure. Most open beaches should max out in the 4ft range late afternoon with 1-2ft waves at sheltered southern corners. There will be a lot of water moving around with this swell so make sure you stay within your limits.

This swell is expected to peak overnight or perhaps early Thursday morning, somewhere between 8ft and maybe 10ft at south facing beaches (even some bigger bombs in the Hunter) but with gusty SW winds at dawn tending S/SW by early/mid morning, then S’ly by mid-late morning. The swell direction should also trend more to the S/SE throughout the day thanks to the swell source moving further east within our swell window. 

However, Thursday will really be a day best suited to those locations well protected from the gusty southerly airstream; an easing trend is likely throughout the day (surf size) but it’ll still remain well above seasonal averages (say, 4-6ft most open beaches, 2-3ft surf inside southern corners).

Again, these swell events create serious south-north currents and it's very easy to find yourself in a world of trouble very quickly. So please stick to a location within your ability.

As for Friday, wave heights will trend more rapidly down from the S/SE (but still likely to be somewhere in the 4-6ft range at south facing beaches early morning, down to 3-5ft by the afternoon, a couple of feet smaller at remaining open beaches), and at this stage winds will probably remain out of the south thanks to a slow moving high pressure system well west of Tasmania. As per the previous few days, your best options will still be at protected locations however by this time winds should have eased sufficiently to allow for a compromise at some open beaches.

This weekend (Apr 11 - 12)

Nothing significant for the weekend right now.

Essentially we’re looking at a continuation of the downwards trend from Thursday’s oversized S’ly tending S/SE swell, and winds should remain generally light both days with clean conditions across the beaches. We may see very small levels of long range S’ly groundswell filter through (from distant storm activity n the Southern Ocean) but at this stage it’ll mainly be small beach break fodder. I’ll review this in more detail on Wednesday though.

Next week (Apr 13 onwards)

The latest model guidance is in general agreement about an amplifying Long Wave Trough through the southern Tasman Sea later in the weekend, which suggests we’ll see an excellent, and possibly sizeable southerly groundswell develop early next week (current ETA late Monday, peaking Tuesday).

It’s too early to have any level of confidence but if things play out as currently expected - with the storm track positioned well to the east of the Australian continent - there’s a fair chance that local winds won’t be greatly affected by it (read: local conditions could be very good). So, if large long period south swells are your thing, it’s worth pencilling in the first half of next week for some solid action. More on this in Wednesday’s update.

Comments

blindboy's picture
blindboy's picture
blindboy Monday, 6 Apr 2015 at 5:37pm

No shortage of swell then!

thermalben's picture
thermalben's picture
thermalben Monday, 6 Apr 2015 at 5:44pm

I am genuinely baffled by the BOM's forecast for late Wed/Thurs (issued 4pm today, i.e. using the same model guidance we had at our disposal).

1m S'ly swell all day Thursday, building to to 2-3m during Thursday evening? Seriously?

Sure, there is some divergence between the models on the timing of the developing S'ly fetch on Wednesday (so, Wednesday's late increase could be delayed by 5-10 hours - but I'm sticking with GFS as it's been very consistent with this system for some time).

But Thursday morning will surely see the new southerly swell in the water, and based on current guidance it's likely to be well above 2-3m (which is a bog standard south swell forecast by BOM standards anyway).

oiley's picture
oiley's picture
oiley Tuesday, 7 Apr 2015 at 8:47am

WAMS for 13th and 14th looking substantial

thermalben's picture
thermalben's picture
thermalben Tuesday, 7 Apr 2015 at 9:54am

Wow.. no change to the BOM's updated Sydney swell forecast - "Southerly below 1 metre" on Wednesday, and "Southerly around 1 metre, increasing to 2 to 3 metres during the evening" on Thursday.

http://www.bom.gov.au/nsw/forecasts/sydneycoast.shtml

This is despite the BOM's own high res charts showing a storm force S/SW flow developing off the Southern NSW coast on Wednesday morning (embedded 40-50kt+ winds):

thermalben's picture
thermalben's picture
thermalben Tuesday, 7 Apr 2015 at 3:07pm

Wow (second time this thread!). The BOM updated their Sydney coastal waters forecast at 11:42am.. check this:

So, in the space of six hours, they've upgraded tomorrow's new S'ly swell from 1m, to "2.5m to 4m around midday".

But.. Thursday is still 1m out of the south all day, ahead of an increase "during the evening" to 2-3m?

mibs-oner's picture
mibs-oner's picture
mibs-oner Tuesday, 7 Apr 2015 at 7:26pm

I gave up on the BOM site ever since you guys started showing the charts. They seem to have a generic comment and never any detail. I also emailed mhl when 3 buoys were out telling them it was a safety risk to boaties but really just wanted to see what they were reading haha.
But serious, modern technology and they give us that shit? Gtfo

DeXtrus's picture
DeXtrus's picture
DeXtrus Tuesday, 7 Apr 2015 at 3:14pm

Yeah and no dangerous surf warning.

Tim Bonython's picture
Tim Bonython's picture
Tim Bonython Tuesday, 7 Apr 2015 at 3:23pm

FROTHING!!!

caml's picture
caml's picture
caml Wednesday, 8 Apr 2015 at 11:31pm

Tim dont overfroth thisz just the lemon next to the pie !

wellymon's picture
wellymon's picture
wellymon Tuesday, 7 Apr 2015 at 4:37pm

light mass: her skirt swirled in a froth of black lace.

mick-free's picture
mick-free's picture
mick-free Tuesday, 7 Apr 2015 at 9:04pm

Dangerous surf warning issued on 6 o'clock news for all beaches for tomorrow.

thermalben's picture
thermalben's picture
thermalben Wednesday, 8 Apr 2015 at 10:44am

Ha! Of course.

mick-free's picture
mick-free's picture
mick-free Wednesday, 8 Apr 2015 at 9:30am

Incoming Eden buoy spiked to 4m.

Craig's picture
Craig's picture
Craig Wednesday, 8 Apr 2015 at 10:16am

5m now.

mick-free's picture
mick-free's picture
mick-free Wednesday, 8 Apr 2015 at 10:18am

7m now cmon!

thermalben's picture
thermalben's picture
thermalben Wednesday, 8 Apr 2015 at 10:45am

Nought but a lazy 1ft of unsurfable swell at Bondi right now. I'll update with screengrabs of set waves thru' the arvo as the swell builds.

thermalben's picture
thermalben's picture
thermalben Wednesday, 8 Apr 2015 at 1:08pm

A little bigger now, some 2ft sets showing. Still nothing major though.

thermalben's picture
thermalben's picture
thermalben Wednesday, 8 Apr 2015 at 1:56pm

A little bigger again. Jeez, this watching-swells-build caper is hard work!

thermalben's picture
thermalben's picture
thermalben Wednesday, 8 Apr 2015 at 3:48pm

Getting there....

blindboy's picture
blindboy's picture
blindboy Wednesday, 8 Apr 2015 at 4:49pm

Not much my way Ben. Some nice long 2ft lines closing out the banks is all. It's all about tomorrow now I would be thinking.

Craig's picture
Craig's picture
Craig Wednesday, 8 Apr 2015 at 5:18pm

Slightly stronger lines now..

Craig's picture
Craig's picture
Craig Wednesday, 8 Apr 2015 at 5:47pm

Bigger set on dark..

southey's picture
southey's picture
southey Thursday, 9 Apr 2015 at 12:40am

Udo , pls don't poke the bees nest . Not with the circus in town , all eyes pointing to Aust and time to kill as they postpone through intense perfection . GL or WSL no deal .