South Australian Forecast by Ben Matson (issued Wednesday May 14th)

Features of the Forecast (tl;dr)

• New swells Thurs (best down south), strong swell building Fri (both coasts though only small on the Mid) with generally good winds
• Large swell Sat but poor winds, easing Sun but still tricky winds
• Small on the Mid all weekend with OK winds
• Smaller both coasts Mon with improving conditions
• Fun surf for the Mid Wed onwards
• Chance for a solid long period swell around next Fri

Recap

The Mid maintained small clean waves on Tuesday in the 1ft+ range at times, easing a touch this morning with early light winds before onshores developed. Wave heights at Victor eased on Tuesday to 1-2ft Middleton but conditions were clean with offshore winds. Size lifted a touch this morning but the sets are super inconsistent and if anything it appears to have eased back this afternoon (though a peak is expected later and overnight). Early light winds are now onshore across the coast.

Small clean lines at Middleton this morning

This week (May 15 - 16)

Generally light winds are expected for the rest of the week, though a troughy pattern will bring about periods of light to moderate onshore breezes at times. So, expect slightly substandard conditions here and there.

As for surf, Thursday’s size (down south) is contingent on whatever appears overnight, as the pulse expected later today was/is expected to be the start of an initially modest new groundswell that would precede a bigger swell for Friday ahead of a peak on Saturday.

Of course, we don’t have an operational wave buoy at Cape du Couedic right now, however Cape Sorell (off Tasmania) is replicating this afternoon’s downwards trend (also apparent in Victoria). Therefore, using Cape Sorell as a proxy, it’d be easy to look at the buoy data and assume the models have overcalled this first swell, especially considering it was sourced from an off-axis fetch in the Southern Ocean earlier this week. But we’ve seen these unusual synoptic setups perform well over the years and gut feel is that the model guidance is pretty good, and that the temporary easing trend (at Cape Sorell, this afternoon) is probably an aberration.

So, let’s hold projections in and around the 3ft mark for MIddleton on Thursday - it will be VERY inconsistent, mind you (off-axis swells always are) - so don’t expect a high wave count. 

I’m not expecting this first swell to amount to much on the Mid Coast either, just some small occasional 1ft sets here and there. But it’s an unusual source with only low/moderate confidence (especially for the gulf) so a regular scan of conditions will be worthwhile. 

Friday’s swell increase will start off undersized, with the biggest waves expected at the end of the day. Early morning may be of a similar size to Thursday (3ft Middleton, 1ft Mid Coast) but with a slightly more consistent lineup, ahead of a building trend that should push 4-6ft at Middleton on dark, and 2ft along the Mid Coast.

It’s worth noting that we’re now approaching the depths of winter, so we have a smaller window for the ‘late’ session (early summer allows for surfing until 8pm+, whilst we lose up to three hours through winter) - and this can change the perception of whether a swell is on track or not.

But the take home message is: Friday's late session will have the biggest waves.

This weekend (May 17 - 18)

A fresh southerly change is expected to sweep across the coast on Saturday morning. 

Model guidance has delayed its arrival a little and there’s an outside chance for a few hours of light winds right at dawn but it won’t last long, so expect most locations to quickly become blown out.

Size wise we’re looking at 5-6ft sets across the Middleton stretch, however this swell will have been generated east of the Mid Coast’s swell window so I’m not expecting the same swell trend here as per Victor, but instead a slow decline in wave heights all weekend (residual energy should however maintain 1-2ft waves both days, mind).

Winds should be more manageable along the Mid though Saturday afternoon may become a little blustery.

Easing size is expected on Sunday though the models are maintaining SE breezes down south and this won’t really allow conditions to improve much at all. I’ll take a closer look at the timing of the change in Friday’s notes to see if things have changed.

Next week (May 19 onwards)

Easing size through the first half of the week will be accompanied by much better conditions as winds become light and then freshen from the NW on Tuesday morning, ahead of a late afternoon frontal system and associated onshore change. 

These fronts will have a series of swells trailing behind, initially generated within an unfavourable part of the swell window (quite north in latitude, and a long way back in the southern Indian Ocean) - that should provide the Mid with a few days of fun surf in and around the 2ft mark from Wednesday thru’ the weekend - however there is a particularly juicy mid-latitude low expected well SW of WA around Monday and Tuesday that is likely to set up a strong long period groundswell around Friday - give or take - that could push the 6ft mark across the Victor stretch. 

It’s still some time away but we’ll take a close look at this in Friday’s update.