Sydney, Hunter and Illawarra Surf Forecast (issued Wednesday 16th April)

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thermalben started the topic in Wednesday, 16 Apr 2014 at 3:58pm

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

Best Days: Thurs: plenty of swell but winds still a bit iffy (aim for the early morning). Easter Fri: plenty of swell and all day offshores. Easter Sat/Sun: strong E'ly groundswell with offshore winds. Late Easter Sat/Sun: strong S'ly groundswell with offshore winds.

Recap: Solid SE swell in the 4-5ft range both days, with a few bigger waves reported at swell magnets. Early W/SW thru’ SW winds in many areas, tending gusty S’ly during the days.

This week (Apr 16-19 onwards)

Now, these are certainly the Tasman swell patterns we all fondly recall when discussing the ‘good ol days’. The surf has been strong and consistent all week, with the only downer being the afternoon wind shift to the south (although there are plenty of beaches coping with it very well).

The low pressure system responsible for this swell is still moving only slowly through the central Tasman Sea; temporarily weakening yesterday before restrengthening a stronger but slightly smaller fetch just off the SW tip of New Zealand this morning. This will lead to a gradual easing in size on Thursday ahead of a renewal of strong swell into Friday

That being said, Thursday’s minor downwards trend won’t be much. We should still see decent 3-4ft waves at exposed beaches and bigger waves at the swell magnets - perhaps with a little less consistency than the last few days - before we kick back up into the 3-5ft range again during Friday (again, with the odd bigger set at swell magnets). Friday's pulse may not quite be in the water at first light but should show most prominently through the middle of the day.

As for local winds, Thursday will play out similar to the last few days with early W/SW thru’ SW winds at many spots before moderate to fresh S’ly winds kick in. Friday looks a lot better overall as a weak ridge moves across the region, bringing moderate W’ly winds to most regions. So at this stage it’s hard to fault Friday for the prospects of great waves right across southern NSW. Very convenient seeing that almost everyone will be on the Easter break!

This weekend (Apr 20-21)

I’ve been discussing this Easter Saturday swell since last Friday (where I mentioned “solid 6ft+ surf is very likely”), and the good news is that there’s been a slight model upgrade over the last few days. 

Ex-TC Ita will tomorrow morning merge with the fabulous Tasman low that’s generating our existing swell, forming an incredible storm force fetch of E/SE winds immediately west of Cook Strait by Thursday afternoon. This will generate a long period E/SE groundswell due to arrive overnight on Friday, and should be well and truly into fifth gear across the Sydney coast by sunrise Saturday

Size wise, we’re looking at inconsistent sets in the 6ft range across exposed locations between the Hunter, Sydney and Wollongong, with a chance for a few 8ft sets on the South Coast. We’ll also see a mid-range SE swell in the mix, from the fetch currently developing off NZ’s SW tip, and this will provide fun 3-4ft waves at open beaches.

One other point to consider - due to various local bathymetry/shoaling effects, not every location will pull in the upper end of this size range. For example, during the large E/NE groundswell from TC Lusi, some regions in Southern NSW saw only half of the size compared to nearby regions. So just keep in mind that you may need to drive around to maximise the size potential (if you're not already familiar with breaks that prefer E/SE swells in the 15-16 second range).

The only slightly negative point for Saturday’s swell is that a strong front will push through the southern Tasman Sea overnight on Friday, and may at some point swing the wind around to a gusty S/SW (especially in the south of the state, which could see 30kts+). However prior to this we’re looking at freshening W/SW winds in most regions between Wollongong, Sydney and the Hunter - so the dawn patrol will certainly be your best choice for a surf. In fact most of the morning should see good conditions in most areas; the afternoon is risky for this possible wind shift though.

Saturday’s E/SE swell will then begin to ease later in the afternoon and throughout Sunday, although it’ll be replaced by a strong S’ly groundswell in the lee of Saturday’s change. 

In fact, model guidance is split on how this change will evolve across southern NSW - one solution (GFS) has better local winds on Saturday and a prominent swell increase for Sunday, whilst the EC solution has the local S/SW wind flow into Saturday afternoon which would bring about a much earlier increase in new S’ly swell (i.e. Saturday afternoon). If the EC solution eventuates we’ll see easing (but still initially strong) S’ly swells throughout Sunday. 

Regardless, both scenarios have a similar peak in size of around 4-6ft at exposed south facing beaches with smaller waves at protected locations (which will mix in with the easing E/SE swell). Let’s wait and see how Friday’s model updates have this timing positioned.

Next week (Apr 22 onwards)

Nothing of major interest standing out in the long range charts at this stage. Another Southern Ocean front/low combo may track south of the Tasman Sea later this weekend and into early next week, which could potentially give rise to a moderate S’ly groundswell around Tuesday of next week (give or take) but with a dynamic short term forecast period ahead let’s worry about that in Friday’s update.

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thermalben Thursday, 17 Apr 2014 at 4:29pm

Based on the latest ASCAT pass (which confirmed the fetch immediately west of Cook Strait this morning), there may be a slight upgrade to the Saturday swell in tomorrow's notes. Either way we're still looking at offshore winds and a large long period event.. should be epic right across the state. Great timing for Easter!

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barstardos1 Thursday, 17 Apr 2014 at 4:41pm

I was just about to say, I reckon this is going to be a bit bigger than just 5'-6'.
60 knots pointed straight at us on an active sea state. Its been a while since we have seen anything like that.
Swellnet models are indicating 3.0m at 12.5s at midday Saturday. I think the models are combining the two swells, The East from Cook Straight and the SSE from below the south Island. Ascat shows two very distinct fetches.
My gut says two swells on top of each other means occasional double ups and occasional double the size!
I am only just recovering from some of the floggings from last weekends swell

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donweather Thursday, 17 Apr 2014 at 5:01pm

barstardos1 wrote: I think the models are combining the two swells, The East from Cook Straight and the SSE from below the south Island.

Agree. They're combining it for SE Qld on Sat arvo as well.
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thermalben Thursday, 17 Apr 2014 at 5:17pm

Yeah well spotted barstardos. Craig and I have been discussing how to best deal with these swell train 'double ups' in our forecast algorithm (because we have no control over the WW3 swell train output), but we've got an idea that we think will compensate and correct the 'surf height forecast' to the right degree.

As for Saturday, 8-10ft seems a reasonable ballpark figure at this stage for much of southern NSW (up from my Wednesday forecast of 6ft to maybe 8ft) although the 50-60kts winds were modeled to only occur for around 12 hours, so let's wait and see how the next ASCAT pass comes out.