South Australian Surf Forecast by Ben Matson (issued Friday 20th May)

Best Days: Sat/Sun: easing swells and gusty N'ly winds, fun blustery conditions down south. Tues: small window of clean waves on the Mid Coast early morning. Tues/Wed: fun, clean waves down south. Thurs/Fri: chance for a tricky W/SW swell across both coasts. 

Recap: Freshening W/NW winds and building swells on Thursday, ahead of clean conditions and plenty of fun groundswell on offer today. The Mid Coast is still pulling in 2-3ft sets (see image below) and winds are light and variable; it’s bigger down at Victor (4ft Middleton) and equally clean under a moderate NW breeze. 

Empty A-frames at South Port, 12:20pm today

This weekend (May 21st - 22nd)

No changes to the weekend forecast. 

Today’s swell is expected to drop steadily from tonight onwards, and northerly winds will freshen throughout Saturday as a dominant high pressure system moves slowly across the region. 

A series of fronts will back up in the Bight on Sunday, tightening the pressure gradient across the coast, with northerly winds reaching gale force before veering NW into the afternoon ahead of a late W’ly tending W/NW change. 

Victor Harbor will be your best option throughout the weekend though size will eventually focus the only rideable options towards Waits and Parsons. Early Saturday morning may offer a few stray 2-3ft sets between Middleton and Day Street but I think they’ll be far and few between. Much smaller surf is then expected throughout Sunday. 

Just bear in mind that it’s going to become quite blustery, especially on Sunday so you’ll need some extra foam underneath yourself to get into the sets properly. 

As for the Mid Coast, Saturday should see some trailing sets from today’s swell though freshening northerlies will probably ruin any chance of a decent wave. There’s a low probability for a brief window of light winds at dawn; if this occurs the reefs may have weak, inconsistent 1-2ft leftovers but in general you’ll be better off at Victor.

Sunday will see even smaller surf and stronger northerly winds. The chances for a late nor’west stormy are about 50/50 right now - the models are not resolving the wind field through the gulf very well - I think there’s a reasonable chance, though we’ll need the wind to swing NW by lunchtime, and then hold above 25kts for at least 4-6 hours. If this occurs we could see junky 2-3ft surf across the Mid Coast through the latter part of the day, however it only takes a small drop in the wind speed (to say, 20kts) and the direction to hold due north instead of north-west, for the surf potential to drop to almost nothing.

So, as always keen an eye on the obs and the surfcams. 

Next week (May 23rd onwards)

Sunday’s late change will cross the coast properly overnight, leaving Monday in a fresh but easing westerly airstream. The front is expected to maintain reasonable strength through the northern Bight so we should see 2-3ft surf across the Mid Coast to start the working week, though not very high in quality.

A slight improvement is expected into the afternoon as the wind eases. 

Tuesday and Wednesday will then see light winds tending northerly and freshening as a weak front slips south of the state. We’ll probably still see a couple of feet of surf across the Mid Coast however aside from Tuesday morning - where we should see a couple of hours of light winds, and consequently clean conditions - it’ll probably become bumpy and eventually blown out.

Victor is a tricky proposition for the first half of next week. As alluded to in Wednesday's notes, I’m still lukewarm about the prospects of any notable size down south, due to a poorly consolidated storm track.

A broad ridge (surface and upper) across the eastern states this weekend will force a series of approaching fronts to stall in the Bight, developing several centres of low pressure. The northern storm track will be focused into the Mid Coast (as described above), however the primary low is expected to drop towards Antarctica. Whilst individual synoptic snapshots look promising, the south-eastern track of this low and the narrow fetch width means the swell potential is low. 

Monday looks a little dicey to begin with thanks to an early gusty (but abating) westerly breeze; it’ll probably veer W/WN into the afternoon but Tuesday and Wednesday look like better bets as winds straighten up from the north with the next approaching front.

As for size - our model has 4ft at Middleton for Monday (peaking in the afternoon) holding into Tuesday, but I think it’s overcalling the influence of the westerly swell; I think we’re more than likely looking at 3ft surf across this stretch (bigger at exposed spots, obviously). But let’s wait and see - either way Wednesday will be on the backside of this swell combo, and we’ll be looking at smaller surf best suited to Waits and Parsons. 

The second half of the week looks really interesting, from a technical point of view. The fetch trailing our mid-week front doesn’t look very impressive - I’d ordinarily dismiss it as a major source of new swell because of its poor consolidation and SE track through the swell window (almost perpendicular to the great circle paths).

However - the pre-frontal NW fetch is of interest. Now, this isn’t aimed in any way towards our coast and under any normal circumstances you’d never consider it a swell source. But, I’ve seen on many occasions good swells result from these fetches, which are actually not quite as far away from the Great Circle paths as you’d think. Couple this in with a strong westward motion on a strengthening surface wind field, and there’s a captured fetch scenario that could play out.

Bottom line is: we may see some unusual W/SW swell from this system around Thursday (outside chance for the leading edge to arrive close to dark on Wednesday). For now I’ll aim for 2ft+ across the Mid Coast and possibly 2-3ft+ at Middleton, with size then easing on Friday. Winds are a little tricky now so I’ll reevaluate that on Monday. 

Have a great weekend!