South Australian Surf Forecast by Ben Matson (issued Friday 2nd October)

Best Days: Sat/Sun/Mon: pulsey long range, long period W/SW swells with fun surf on the Mid and clean but inconsistent surf down south. Tues: strong combo of swells but with mainly onshore winds on the Mid (clean down south). Wed: potentially light cross-offshore winds on the Mid and good surf. 

Recap: Thursday remained small as expected across most of the SA coast, and winds swing onshore at Victor in the morning, rendering most beaches quite bumpy. A small new groundswell has filled into the region today, and wave heights have increased bang on as per expectations - we’re seeing smooth 2-3ft sets at Middleton (as per the images below), and even the Mid Coast has glassy 1.5ft sets across the reefs. 

Lovely glassy lines on the Mid Coast; shame it ain't 4ft bigger

This weekend (Oct 3 - 4)

No major changes to the weekend forecast. 

We’ve got a series of strong new W’ly tending W/SW swells, originating from a weather system I’ve been discussing since last Monday (11 days ago - see the original extended notes here).

The first of these swells - due to arrive in the early hours of Saturday morning - will have been generated mainly by a sustained belt of NW winds on the eastern flank of a large Long Wave Trough in the Southern Indian Ocean. Swell periods will be quite strong thanks to several embedded features (read: small lows) within the NW flow that have displayed very strong winds in excess of 40-50kts.

Much of these winds are aimed away from our coast, but the sheer strength and duration will override the directional deficiencies and should allow for a healthy spread back into the mainland.

However, westerly swells usually create very large ranges in wave heights across the coast compared to what you’d expect at exposed part of the state - but the good news is that this direction is great for the Mid Coast. It’s the Victor stretch that dips out in the size department. 

Wave heights should building slowly through Saturday, holding into Sunday with the afternoons the pick along the Mid Coast with 2-3ft surf. Saturday is at risk of a freshening northerly breeze as a weak front slips south of the state, but I don’t there’ll be much more than 10-15kts - we should be OK for most of the day. Sunday is however the pick of the weekend with light variable winds as a ridge develops across the region.

I’m skeptical that we’ll see any great size at Victor over the weekend, and I still think our forecast model for Middleton is slightly overcalling Sunday’s size (3-5ft). To me we’re looking at smaller surf building to 2-3ft+ at Middleton on Saturday with slightly bigger waves through Sunday (3-4ft). The main points to remember is that locations close to Victor (i.e. Chiton etc) will probably be a lot smaller than usual due to the direction, however exposed locations will be bigger (Waits and Parsons often defy local shadowing effects due to their more favourable bathymetry).

Either way, conditions are looking really good both days with freshening offshore Saturday and light variable winds Sunday. 

Next week (Oct 5 onwards)

Sunday’s long period westerly energy will continue through Monday - I think we’ll see a similar size early morning before it tapers off into the afternoon. Moderate N’ly winds should maintain clean conditions down south, but there is a risk of some chop developing across the Mid Coast.

The rest of the forecast period looks quite exciting. Very late Monday, the leading edge of a very long period swell (Tp of around 22-23 seconds) is expected to make landfall. This will have been generated by the main engine room of the Long Wave Trough in the Indian Ocean, with another intense low migrating through the Southern Ocean with core wind speeds up to 50-60kts at times - and we’re looking at an initial W’ly swell tending W/SW over the coming days. 

This storm track looks a little better (strength/alignment/longitude) than the one expected to generate Sunday’s swell, so we can expect a little more size across the Victor region compared to the weekend. However, there will once again be a strong westerly component in the swell direction.

The main concern with Tuesday are the local winds, as a cold front pushes through the Bight. This will strengthen NW winds about the region (fine for Victor, bad news for the Mid) ahead of a gusty SW change in the evening. However, I think we’ll probably see a window of light winds at some point in the morning. Let's see how the model guidance is stacking up on Monday.

The Mid Coast should build to a solid 3ft+ throughout the afternoon (maybe a little more if the front arrives earlier than expected, and nudges up the windswell component) but the early morning is likely to be slightly smaller around 2-3ft. Down south, the initial W’ly component may shave off size at Middleton to 3-4ft in the morning however by the afternoon we’re looking at solid 4-5ft surf with bigger waves at exposed locations.

Tuesday’s swell will then ease slowly through Wednesday but it’ll be supplemented by strong short range W/SW tending SW swell from Tuesday's frontal passage. This should maintain 2-3ft surf across the Mid Coast, and the good news is that a quickly advancing ridge of high pressure should allow lighter S/SE winds to develop in the gulf, rapidly improving conditions. Wednesday could therefore see some really nice waves along there Mid Coast.

Lighter winds are also expected at Victor on Wednesday though they’ll mainly be onshore. Wave heights should remain strong here with 3-5ft surf at MIddleton. 

Wednesday’s swell is expected to hold into early Thursday before easing into the afternoon, thanks to a small blocking ridge that’ll momentarily down the swell window. This easing trend should persist into Friday.

One final of swell from the LWT progression is likely sometime next weekend - nowhere near as big or strong as what we’re expecting at other points over the preceding week - and then an extended period of smaller surf is likely throughout the following week as a general blocking pattern develops across our broader swell window.

So, make the most of the next week of waves as the following week doesn’t look anywhere near as exciting.

Craig will be back on deck on Monday to run you through the upcoming events. Have a great weekend!

Nice lines at Middleton

Just behind the inside section