South-east Queensland and Northern NSW Surf Forecast by Ben Matson (issued Monday 14th December)

Features of the Forecast (tl;dr)

• Very large surf easing Tues (much smaller Sunny Coast), levelling out from Wed thru' the weekend
• Risk of N/NE winds from Tues-Fri, though mainly south from Ballina (pockets of light winds possible)
• Should be OK options in SE Qld and Far Northern NSW all week though may be bumpy at times
• Generally fun weekend of waves at open beaches and outer points
• Slow building E/NE cyclone swell from Sun, peaking later Mon/Tues, possibly quite solid, light winds keeping conditions clean

Recap: Saturday ended up a little better than expected thanks to winds being lighter S’ly across quite a few coasts through the day. The lighter winds was the result of a complex trough ahead of a convergence line that moved up from the south, stalling near the border late Saturday and dumping about 600mm of rain across some regions over the following 36 hours. Surf size built from the E/SE through Saturday and then rapidly increases into Sunday as gale to storm force winds from the SE thru’ E lashed the entire region. Wave heights seem to reach a late peak in the 10-12ft range, sustaining this size (with similar winds) through this morning, though we’ve seen conditions abate through the day. For what’s worth the focal point of the trough responsible for this impressive swell was located a little further north than Friday’s models suggested, resulting in a broader spread of maximum surf size up into Far Northern NSW and even parts of the Gold Coast. However the Sunshine Coast was much smaller, peaking around 8ft at exposed beaches, much smaller along the protected points. 

First Point Noosa humming around lunchtime

This week (Dec 15 - 18)

Righto. So, it’s currently very large, and the persistent gales of the large few days are starting to ease off.

I suppose at this juncture we can talk in broad brushstrokes, because the surf potential for the short term will be heavily dependent on just a couple of factors: (1) the state of the banks, following this scouring event, and (2) whether the modeled N/NE winds get up to strength. 

Size will likely ease rapidly into Tuesday (probably 6-8ft early some exposed coasts, mainly Northern NSW, tho’ much smaller on the Sunny Coast) and by Wednesday afternoon we’ll be into a background 3-5ft E’ly swell originating from a broad ridge stretching across the Northern Tasman Sea, out into the South Pacific. So, expect exposed locations to remain overpowered on Tuesday but it'll slowly start to throttle back.

It’s the N/NE winds that are of concern, especially for Northern NSW, particularly the Mid North Coast. 

Ordinarily, these kinds of coastal troughs usually move south, and then retreat eastwards back out into the Tasman Sea. As a result we see light winds in the wake of the trough and then some form of southerly as it moves east. 

In this case, the trough is going to slowly cross the coast, so the northerly quadrant winds on its eastern flank - that would normally remain well offshore - are instead pulled closer to the mainland, affecting surf quality.

The tricky part here is working out which coasts will be most affected. Not only do we not want to waste a swell event like this, it’s also likely that the model guidance is perhaps overstating the synoptic effects across some regions. 

Now, for clarity, model guidance is calling for 4 days of 15-20kt+ N/NE winds cross the Mid North Coast, lighter across SE Qld around 12-15kts. Certainly enough to spoil conditions no matter where you are.

However in this instance I think the models are exaggerating winds along the Gold and Sunshine Coast. The eastern extremities of our scalloped coastline usually pick up maximum wind strength, and with the surface trough still lingering about the inland region for the remainder of the week, I think there’s a fair chance its effects will extend to a handful of coastal regions, especially north from the Tweed Coast.

That’s not to say the wind won’t be out of the north, it’s just that we’re still likely to experience workable conditions in SE Qld for most of this week, especially later on once the swell drops to more manageable levels where protected northern corners can offer some shelter - in in fact the wind comes up. So don't write it off.

South from Byron, these pockets of more favourable conditions are less likely to eventuate but still likely that we’ll see OK winds from time to time=. So, prepare for the worst but keep a sneaky eye out for windows of opportunity. They’ll be ripe for the picking from Wednesday once things calm down a little more. 

This weekend (Dec 19 - 20)

Whatever N’ly winds we see this week, we’ll see even less of it on Saturday. A gusty S’ly change is then due into the Mid North Coast on Sunday, providing a small boost in short range S’ly swell to south facing beaches. Current expectations that the S’ly change will stall somewhere south of Yamba so Sunday will probably see light winds north across the Far Northern NSW and SE Qld regions. 

As for surf, persistent E’ly swells will dominate this weekend, sourced from the all-week stationary ridge across the Northern Tasman Sea and the South Pacific. The tail end of this fetch will be reinforced by a second cyclone (TC Zazu) which formed south of Samoa this morning, though TC Zazu will track rapidly east and won’t be a major contributor of swell overall. 

Wave heights should maintain 3-4ft, occ 3-5ft at exposed beaches all weekend, smaller running down the points, and offering plenty of options (banks pending, of course). It’s shaping up to a be a fairly standard round of trade swell, so there’ll be worthwhile options at many coasts. 
  
Next week (Dec 21 onwards)

TC Yasa was announced this morning, having formed NW of Fiji following a gradual evolution over the weekend. There are no steering influences across this region right now so TC Yasa will meander about for a few days, remaining slow moving between Fiji and Vanuatu, generally tucked up inside the swell shadow of New Caledonia. As such, its swell potential is somewhat diminished for the short term, even though winds will be approaching storm to hurricane force by Wednesday (Cat 3, i.e. Severe Tropical Cyclone).


The leading edge of new swell is on target to glance the coast over the weekend, though initially it won’t have a lot of size - the potential for cyclone swell will increase markedly next week, as TC Yasa is expected to enter our swell window properly late Friday or early Saturday.

Ordinarily I’m reluctant to look too closely at long range modelling for tropical cyclones as it’s usually erratic and unreliable. But, so far all of the global models have been pretty good with this system (probably due to a lack of steering influences) and at this point in time they’re all consistent with a pathway into our swell window by Saturday, followed by a slow southward trajectory towards New Zealand, and then a slight curve to the south-west, into the Tasman Sea. 

This storm track actually looks like it’ll favour Southern NSW more so than Northern NSW and SE Qld, though we will pick sup some decent E’ly groundswell early in the week, from the weekend’s developments within our swell window. Let’s peg waves in the 6-8ft range around Tuesday (bigger Northern NSW, slightly smaller SE Qld), though if we see a further anti-clockwise curve in the storm track - i.e. to the west - then this outlook may be revised upwards, post-haste. 

Regardless, it’s looking to be a very active period of quality surf in the leadup towards Xmas. With work shutting down for a lot of crew next week there’s going to be plenty of reasons to justify hitting the road looking for waves. 

Exciting times! More in Wednesday's update.