Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Monday 20th April)

Best Days: Tues: unusual waves at novelty locations. Wed: large combo of easing SE windswell and new SE groundswell, and a possible wind shift to the S/SW then SW (and subsequently improving conditions). Thurs: Solid but steadily easing SE tending S'ly swell with better conditions. Sat: small E/NE groundswell with offshore winds. Sun: strong building S'ly swell with offshore winds. 

Recap: Small leftover swells all weekend with a rapid increase in short range S’ly windswell late Sunday behind a southerly change. Pretty uninspiring all round. Steadily building SE swell all day today with strengthening S/SE winds (Wattamolla just recorded a gust of 65kt - 120km/hr - which is hurricane strength!).

This week (Apr 21 - 24)

No surprises to see a total washout today. Whilst Sunday’s size estimations were pretty close (with the building S’ly windswell), it was undersized this morning and the upwards trend today has been slow. But this is certainly not unusual for these kinds of close-proximity, dynamic weather systems. 

The broader synoptic outlook is a little complex as the atmospheric models have a couple of solutions possible for the next few days. Most models have an ECL deepening in the vicinity of Seal Rocks through Tuesday, of which gale to storm force S/SE winds along its southern flank will create very large seas and swells for most regions (biggest in the Hunter, with slightly smaller surf and easing winds as you track south). 

Side note: When is an east coast low not an East Coast Low? Read Craig Brokensha's article here.

I’m not sure if it’s worth putting a size estimation on things as there’ll be little surfing opportunities at most locations, but we’re probably looking at 10-12ft surf across the exposed Hunter coast, 8-10ft+ in Sydney, and then 6-8ft+ south from the Illawarra (smaller in the Far South). Winds will be strongest in the Hunter (40kts+) but will ease slowly with increasing southerly latitude. Expect a S/SE flow for the most part but it should tending southerly throughout the day. 

Tuesday’s fetch will weaken throughout the afternoon and overnight, so this swell source will abate into Wednesday. However, the GFS solution has a secondary low pressure centre in the central Tasman Sea that’s expected to intensify and retrograde back to the coast. This enhancement on top of a very active sea state should generate a strong secondary push of better quality groundswell that’s expected to push across most beaches on Wednesday - probably not early morning, more likely during the middle of the day.

Now, I’m taking a punt in calling this secondary swell because it’s going to be little hard to decipher from the residual noise leftover from Tuesday (I think the new pulse should be worthy of 6-8ft+, and this could be the residual size range left over early Wednesday). And, the models are not in close agreement with the synoptic evolution from Wednesday onwards either (I’m leaning with GFS as it’s been pretty good on this system so far).

But what gets me slightly excited about Wednesday’s surf prospects is that winds are expected to veer S/SW throughout the day, maybe even SW in some areas, as the primary low (near Seal Rocks on Tuesday) moves offshore and broadens into a more typical ‘Tasman Low’ structure. 

So, boiling this all down and we’re probably looking at 6-8ft+ surf at exposed spots through Wednesday, with a noticeable kick in definition through the middle of the day and into the afternoon. Keep an eye on local wind observations as this directional shift could really start to favour quite a few breaks, and would lead to a steady improvement right across the region. 

As per normal I’ll update observations and other information in the comments below through Tuesday and early Wednesday.

For the rest of the week, it’s a little hard to be totally confident as the model guidance is a little mixed, but we’re looking at strong but steadily abating wave heights from Thursday onwards (from the SE, tending S’ly) and rapidly easing SW winds on Thursday tending W’ly on Friday. 

We may also see some moderate E/NE swell from a broad infeed into the Tasman trough associated with the ECL, but this currently looks like it’ll be best aligned towards the South Coast and Tasmania’s East Coast (maybe some 3ft sets through late Thurs/Fri if we’re lucky). I’ll have a closer look at this on Wednesday.

This weekend (Apr 25 - 26)

We’ve got a couple of swell sources for the weekend.

Our southerly swell will be all but gone by this time, however Saturday should see a combination of easing E/NE swell (feeding into the central Tasman trough) plus a small long range E/NE swell from a developing tropical system north-east of New Zealand over the coming days. Set waves should be somewhere in the 2-3ft range - albeit quite inconsistent - and it’ll be nice and clean with freshening W’ly winds. This swell should continue through Sunday.

Also for Sunday, we’re looking at another strong front crossing the SE corner of the country that looks like it’s going to extend SW gales out of eastern Bass Strait early in the day.

We’re ultimately looking at a couple of days of strong southerly swell from the broader system, the first of which should start to build through Sunday - but with winds maintaining a W/SW direction -  so conditions should remain nice and clean on the surface. Early estimates are for 4-5ft at south facing beaches by Sunday afternoon but I’ll have a better idea on this in Wednesday’s update.   

Next week (Apr 27 onwards)

More strong south swell for Monday onwards but with winds probably veering more southerly at times (early sou’westers likely though). This will be our primary focus through the first half of next week and could get quite sizey at times, somewhere north of 6ft at south facing beaches on Monday and Tuesday, with a probably easing trend Wednesday onwards. Let’s see how the model updates pan out over the remainder of the week.