South Australian Forecast by Craig Brokensha (issued Friday 7th September)

Best Days: South Coast Saturday and Sunday (more consistent), Monday both coasts, South Coast Tuesday morning, then protected spots from Wednesday

Recap

Small to tiny leftovers across the South Coast yesterday, best at Waits and Parson early before winds shifted to the west. The Mid Coast was also relatively clean early and around 1-1.5ft, but once the change hit, we saw a rapid increase in size with stormy 3ft waves into the afternoon.

This morning we've seen winds go offshore on the Mid Coast creating great conditions with 2-3ft of swell, a touch bumpy now, while the South Coast is slow with the groundswell still on the build. Middleton was an infrequent 2-3ft, but we should see more size into this afternoon as winds remain generally favourable from the W/NW.

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This weekend and next week (Sep 8 - 14)

The W/SW groundswell filling in today is due to peak this afternoon, mixed in with mid-period W/SW energy and we'll see both ease off through tomorrow.

Conditions will be great for the South Coast with a NW tending W/NW offshore and easing sets from an inconsistent 3ft along the Middleton stretch, 2ft on the Mid Coast.

Into Sunday we'll see our new more consistent mid-period SW swell fill in, generated by a broad though relatively weak polar front that's currently projecting up towards and under WA.

A fetch of W/SW gales were initially generated, with weaker sub-gale force winds now moving towards us, and we should see this swell offering a fun kick in size Sunday to 3ft off Middleton and 2ft on the sets on the favourable parts of the tide across the Mid Coast.

Conditions will be great again for the South Coast with a NW-W/NW offshore while the Mid Coast will remain bumpy and average. Of the two days over the weekend, Sunday is probably the go to for more consistency.

Moving into Monday and our large long-period pumping W/SW groundswell is still on track, with a relatively weak frontal system that's currently just north of the Heard Island region expected to strengthen significantly under the influence of the Long Wave Trough sitting over WA.

We'll see a great fetch of severe-gale to storm-force W'ly winds projected through our western swell window from this evening through tomorrow before dipping south-east while passing under the Bight Sunday.

A large long-period W/SW groundswell will be generated, arriving overnight and peaking Monday to 3ft on the Mid Coast and 4-6ft off Middleton along with excellent moderate to fresh offshore N'ly winds, N/NW into the afternoon.

The Mid Coast should be OK early with N/NE winds before shifting more onshore.

Tuesday morning looks great as well as the swell eases with a gusty pre-frontal N/NW'ly ahead of a W/NW change into the afternoon.

This change will be related to a vigorous mid-latitude front developing south-west of WA, sliding in tight under their state and through the Bight while generating a fetch of severe-gale W/SW winds.

A large, long-period acute W/SW groundswell will be generated, mixed in with windswell as the system pushes across us on Wednesday.

The swell should fill in Wednesday and reach 4ft on the Mid Coast into the afternoon, while with the west direction Middleton will be sheltered and only reach a similar size later in the day. Winds look as if they'll be out of the W most of the day, similar Thursday as the swell eases favouring protected spots.

We'll have a closer look at this storm and an even broader polar front developing mid-week on Monday. Have a great weekend!