South Australian Forecast by Craig Brokensha (issued Monday 3rd September)

Best Days: Tuesday South Coast, Thursday afternoon South Coast, Mid Coast Friday morning and South Coast all day, South Coast Saturday through early next week

Recap

Small and clean waves to start the weekend down South with onshore choppy 1-1.5ft sets on the Mid Coast.

Our large new S/SW groundswell for Sunday came in strong with variable winds from the eastern quadrant through the morning ahead of moderate to fresh sea breezes. With the size and direction of the swell, the deepwater reefs around Victor offered good challenging surf, tiny but clean on the Mid Coast.

The swell has eased back overnight leaving still large and lumpy waves this morning, with surf in the 1ft range on the Mid again.

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This week and weekend (Sep 4 – 9)

We'll see the large S/SW groundswell from the weekend continuing to ease through tomorrow and Wednesday as winds continue to improve.

A high moving in from the west will direct fresh N/NE winds across the region all day tomorrow and Middleton should still see sets to 3ft early, down to 2ft later becoming more manageable at swell magnets.

Wednesday will be a bit average with small to tiny leftovers, fading through the day under stronger N/NE tending N'ly winds.

This strengthening N'ly will be a result of a strong mid-latitude front pushing in from the west, and with it we'll see a mix of moderate to large long-period W/SW groundswell and close-range W/SW swell filling in.

The groundswell started to be generated later last week by a strong polar frontal progression that developed in the Heard Island region.

A fetch of strong to gale-force W/SW winds set up an active sea state for a stronger front to move over, projecting gale to near severe-gale-force winds slowly up towards WA.

The front is now west-southwest of WA and will push across their state tomorrow afternoon and evening. A moderate to large W/SW groundswell will be produced, with it due to build through Thursday afternoon ahead of a peak on Friday.

We'll see the remnants of the storm continue east and through the Bight over the coming days, with a great fetch of W/SW gales generated through the Mid Coast's swell window Wednesday and then better aligned fetch of W/SW gales through the South Coast's swell window on Thursday.

The first burst will generate a solid increase in W/SW swell for the Mid Coast along with the groundswell Thursday afternoon, peaking Friday with the secondary fetch generating an additional SW swell for Friday afternoon on the South Coast.

The Mid looks to build to a consistent 3ft Thursday afternoon, persisting around the same size Friday but with fresh W/NW tending W'ly winds on the former, moderate W/NW breezes on the later, freshening into the afternoon.

The South Coast will better with the swell building from a low base Thursday morning and reaching 3ft on the sets by dark, with bigger 4ft sets developing through Friday under that favourable offshore breeze.

Fun waves are expected over the weekend as the mix of swells ease through Saturday under a persistent NW offshore, while Sunday looks to remain clean as a new SW groundswell kicks into the afternoon.

The source of this swell and a reinforcing W/SW swell for Monday will be firslty a vigorous polar front forming south-west of WA, and then secondary higher (more northerly) positioned zonal W'ly fetch.
These swells look to arrive with great winds early next week, but more on this Wednesday.