Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Wed 12th Apr)

Forecast Summary (tl;dr)

• Moderate+ S/SE swell persisting Wed thru' Fri
• Good conditions Wed with light winds; developing S/SW winds Thurs morning onwards
• Fun weekend mix of easing S/SE swells and small E/SE swell, biggest Sat
• SE-ESE swell late Sun, continues into Mon with good winds
• Mod/large E/NE swells building mid next week as trough/block pattern sets up
• Dynamic pattern with potential TC moving southwards next week
• Potential for more S swell in the medium term

Recap

Very solid S swell energy peaked through yesterday with most S exposed breaks seeing 8ft sets and deep-water S facing reefs seeing solid 10-12ft+ surf under a mostly W’ly flow that tended S-S/SE in the a’noon. Today has come off the peak of the swell with size dropping to 3-5ft at S exposed breaks, bigger 6ft on the Hunter. Winds are light W/NW-NW tending variable through the day.

This week (Apr 12 - 14)

The broad, complex Tasman low which generated large S swells is now positioned on the other side of New Zealand with a lingering fetch of SSE-SE winds under the South Island. A much smaller, cut-off low NW  of Tasmania is linked via a trough line to TC Ilsa  off the Kimberly Coast and is expected to drift into the Tasman Sea tomorrow bringing a fresh S’ly flow to round off the week. A dynamic trough blocking pattern is then expected to unfold in the medium term. Details below. 

In the short run and variable winds through tomorrow morning provide a small window of clean conditions before S’ly winds freshen through the morning so you’ll need to get up early for clean conditions, which will extend a bit longer on the Hunter. We should see swell direction come around a little more SSE tomorrow, offsetting the drop in wave period. Expect size in the 3-4ft range, bigger 4-5ft on the Hunter, with size grading smaller into more protected spots once the S’ly flow kicks in. Winds will tend more SSE-SE in the a’noon.

Similar winds Fri with a S’ly flow expected through the day and only a brief window of lighter SW breezes north of the Harbour. The fetch below the South Island is expected to provide a rebuild in surf heights from the SSE-SE, up into the 3-5ft range (possibly with some bigger sets), with smaller surf in more sheltered corners. There’s low odds that the southwards movement of the broad, weak low in the Tasman will drag a more SSW flow across temperate NSW Fri a’noon. Worth keeping tabs on local winds through the a’noon for improving conditions.

Thundering in yesterday, smaller today

This weekend (Apr 15 - 16)

Sat morning is looking pretty good with the southwards moving low and an approaching front bringing a morning W’ly breeze which should groom plenty of leftover SSE swell nicely. Expect 3-4ft sets early easing through the day. With pre-frontal N’ly winds freshening in the a’noon confining clean conditions to S facing beaches.

Sunday looks a bit weaker now, with the fetch out of Cook Strait being delayed in development by 12-24hrs compared to Mondays notes. Winds will clock around from NW through W/NW and W/SW as the front passes into the Tasman with easing swells through most of the day. We’re likely to see a small boost from the E/SE later in the a’noon in some areas to 2-3ft. This may occur right around dark in some places north of Sydney.

Next week (Apr 17 onwards)

As Ben highlighted in Mondays notes we have a very dynamic outlook into next week with a large ‘trough-block” pattern establishing through the Tasman Sea and possibly extending int the South Pacific swell window. There’s still substantial variability run to run and between models so we’ll be revising these estimates up or down on Fri.

For now, we should see a morning SW flow Mon before S’lies develop in the wake of the front, which is expected to quickly move away to the SW. SE-ESE swell from the late Cook Strait fetch supplies nice 3ft surf, with a few 4ft sets on offer.

Tues looks like a low point with residual ESE-E swell in the 2-3ft range and light S-SE winds after a morning land breeze. 

Through this period we’ll see E-E/NE winds infeeding into the long trough line with good odds of a discreet low forming in the trough line between New Caledonia and the North Island. These winds are aimed directly at the East Coast over a broad area which should see widespread E’ly quadrant swell develop from Wed, along with SE swell from the lower Tasman. GFS has backed down on windspeeds feeding into this broadscale trough/low pattern with wave models suggesting surf heights in the 4-5ft range from this source, likely pulsing around this level Wed-Fri.

Larger surf is still a possibility with EC model suggesting stronger windspeeds in the fetch, albeit aimed more at sub-tropical regions. 

So pencil in a few days of solid E swell from Wed-Fri with winds looking light S’ly although the presence of troughs makes winds look very fickle.

Complicating matters further GFS has been suggesting a Tropical cyclone forming in the Coral Sea early next week with a proposed S’wards movement, parallel to the coast. Latest GFS model runs look pretty terrifying if this coast hugging system comes into existence as modelled. 

Huge swells and destructive weather can’t be ruled out at this point. This is a long way off and thus subject to low confidence so check back in Fri and in the comments as we come to grips with this dynamic pattern.

Seeya then.