South Australian Forecast by Craig Brokensha (issued Monday 20th August)

Best Days: South Coast tomorrow and Wednesday, swell magnets Thursday morning, keen surfers Friday through Sunday mornings

Recap

A kick in new W/SW swell through Saturday to a bumpy 2ft to occasionally 3ft on the Mid Coast, dropping back to 1-2ft on Sunday, while the South Coast was also bumpy with a cross-shore wind and low point in swell, deteriorating as the swell kicked into the afternoon. Sunday was poor with strong S/SW winds and a stormy mix of swells to 3-5ft.

This morning was much better with a drop in swell back to 3ft off Middleton under an offshore breeze, tiny but fun across the Mid Coast for beginners.

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This week and weekend (Aug 21 - 26)

Tomorrow's swell has been upgraded, with the low linked to the swell coming in stronger and remaining longer lived than forecast on Friday.

This seems to have been the theme the last couple of weeks under the effects of a strong negative SAM signal, with the models struggling to grasp the initial intensity of incoming frontal systems.

The low formed over the weekend and generated a tight fetch of severe-gale to storm-force W/SW winds while moving through our south-western swell window. The low is now weakening to our south and will pass across Tassie this evening.

A strong long-period SW groundswell should build into tomorrow afternoon, reaching 4-5ft off Middleton by dark, while the Mid Coast only looks to reach 1ft or so with the swell not quite from the right direction.

Winds look favourable for semi-protected spots with a persistent W/NW to sometimes NW breeze tomorrow (likely N/NE on the Mid Coast early), while Wednesday will be excellent at more exposed breaks with a moderate to fresh N/NE offshore. The swell looks to ease back quickly from 3ft to maybe 4ft off Middleton, down to 2ft+ into the afternoon.

A low point in swell is due Thursday across all spots but conditions will remain clean with a variable tending E'ly breeze as a broad mid-latitude starts to wander across us.

This wandering nature is affecting the wind outlook for the end of the week and weekend, with generally light E'ly breezes each morning, SE into the afternoons.

We'll see some new long-range and very inconsistent groundswell filling in on Friday, with additional pulses through the weekend with a touch more consistency.

The first pulse will be large in WA, produced by a strong polar storm that developed west of Heard Island over the weekend, but by the time it reaches us it will be super inconsistent and smaller.

The long-period forerunners are due to arrive through Thursday but the swell isn't expected to peak until Friday.

We're looking at very inconsistent 3ft to occasionally 4ft sets off Middleton with not much in between, while the Mid Coast looks to come in at 1-1.5ft on the favourable parts of the tide.

A reinforcing and slightly more consistent swell is due Saturday to an infrequent 3ft off Middleton, smaller and to 1ft on the Mid Coast, similar Sunday. Longer term it looks like we'll see a series of vigorous fronts fire up and push across us through next week, but more on this Wednesday.