South-east Queensland and Northern NSW Surf Forecast by Ben Matson (issued Mon 10th Apr)

Forecast Summary (tl;dr)

• Large renewal of S'ly swell Tues AM (MNC), reaching Northern Rivers into the a'noon, arriving SE Qld late (much smaller here); clean conditions with light winds
• Swell persisting into Wed AM but easing; clean conditions with light winds. Expect much smaller surf north of the border.
• Moderate+ S/SE swell persisting across Northern NSW Thurs thru' Sat; only small in SE Qld but workable
• Sat the pick of the weekend
• Solid E/NE swells building early next week
• More S'ly swells for Northern NSW beyond that

Recap

Easterly swells delivered plenty of fun waves on Saturday in the 3ft range (a touch smaller in SE Qld), easing further into Sunday before a new south swell built steadily across Northern NSW during the afternoon. We've seen large S'ly swells today, reaching 5-6ft across some parts of Northern NSW, though the acute direction is resulting in a wide range in size at remaining beaches, including much of SE Qld (3-4ft south facing beaches, much smaller elsewhere). Conditions have generally been clean with offshore winds; Saturday afternoon the only outlier with a period of northerlies. 

Solid in Coffs Harbour this morning

This week (Apr 11 - 14)

A deep Tasman low positioned midway between the Apple Isle and New Zealand is responsible for the current south swell. And it's not over yet.

A secondary fetch of broader southerly gales are wrapping around its western flank (see below), buffeting the eastern Tasmania coast with large windy swells, and this energy will push across the Mid North Coast NSW on Tuesday morning, reaching the Northern Rivers into the afternoon and SE Qld late in the day.

In similarity to today, the swell will remain acutely south, which means there'll be a very wide variation in surf size between south swell magnets and sheltered southern ends. However, the sustained nature of the parent system, and the fact that the current fetch is working upon the active sea state generated by the last few days of wind, means that surf size will become even bigger into tomorrow than what we saw today. 

The only downer I can see - other than the usual performance caveats regarding southerly swells at your local beach - is that the primary fetch is located a little further west than is ideal. So, the resulting swell will have to bend quite a bit into Northern NSW, and bend a lot into SE Qld.

How big? Keeping in mind a temporary low point on Tuesday morning (lasting longer in northern locales than in the south), reliable south facing beaches in Northern NSW should push into the 6-8ft mark at the peak of the swell by late Tuesday. Elsewhere, beaches not open to the south will be smaller though expect things to be a notch or two higher than today.

SE Qld won't pick up as much size, and I'm always mindful to downplay south swells north of the border. So let's keep things not too far off what they were today: inconsistent 2ft sets at most open beaches, but pushing 3-4ft+ at south swell magnets (note: this peak may not show properly until Wednesday morning). Expect slightly undersized conditions for much of Tuesday.

This S'ly swell event will slowly ease from Wednesday onwards - initially still large across exposed regions, as per late Tuesday - and the good news is that we're expecting light variable winds both days under a weak pressure gradient. So conditions will be excellent.

The even better news is that there's a stack of more swell on the way. 

Although the Tasman low is now weakening, it will remain slow moving for a few days yet and a broad S/SE fetch will develop off the SW tip of NZ's South Island that'll maintain low-end S/SE gales in our swell window until Thursday.

This renewal of energy will arrest the otherwise easing southerly swell trend from Wednesday onwards, generating 3-5ft surf across Northern NSW from Thursday thru' Saturday (the upper end of this size range more likely Thurs than the other days). 

Expect smaller surf throughout SE Qld, though the swing in the swell direction to the S/SE should maintain inconsistent waves in the 2ft+ range at most open beaches, with bigger 3ft+ sets at south swell magnets. 

There is a risk of southerly winds developing sometime Thursday, holding into Friday, but there should be enough size (and east in the southerly swell direction) to favour partially sheltered spots - though super protected points will remain very small. 

This weekend (Apr 15 - 16)

As mentioned above, S/SE swells will hold into Saturday but then ease into Sunday. 

We've also got a minor flush of E/SE swell due this weekend, sourced from a small fetch of gales exiting western Cook Strait later Thursday and into Friday. 

Most of this fetch will be aimed towards the South Coast (and Tasmania's East Coast) so we'll only see small sets to 2ft+ across the Mid North Coast, a little smaller along the Northern Rivers, and SE Qld won't pick up much. 

Saturday is the pick of the weekend anyway with the most size and best conditions under a light wind pattern. Sunday is at risk of freshening northerlies. 

Next week (Apr 17 onwards)

We've got a complex, dynamic long range forecast right now, thanks to a redevelopment of what's essentially the same broadscale troughiness over the Tasman Sea related to our current south swell, and this week's impending S/SE energy.

A slow down in the eastward progression of long wave troughs - a blocking pattern if you will - is likely to allow the surface trough to deepen a number of low pressure centres, that will in turn form a broad E/NE fetch across the NZ region next weekend. This looks to generate a heavy E/NE swell for the Australian East Coast, arriving early next week and peaking Tues/Wed. 

It's too early to have confidence in the likely size range and duration (and focus of the biggest surf), but early indications are for some very large waves, probably into the 6-8ft range, with periods of clean conditions as the regional frontal progression resumes across the SE corner of the continent (also generating some fresh S'ly swells for the second half of that week).

Let's see how the model guidance is stacking up on Wednesday!