South Australian Forecast by Craig Brokensha (issued Friday December 20th)

Best Days: Later tomorrow and early Sunday for the keen Mid Coast, South Coast for the keen Tuesday morning but more so Wednesday

Features of the Forecast (tl;dr)

• Small-mod sized W/SW building tomorrow, holding Sun AM
• Fresh to strong S/SE winds tomorrow, early S/SE tending S/SW winds Sun, strong later
• Moderate sized, mid-period SW swell building Mon with mod-fresh S/SW winds
• Easing swell Tue with E/NE tending S/SE winds down South E tending SW on the Mid
• Smaller Wed with fresh N/NE tending variable winds ahead of late, weak sea breezes
• Small to moderate sized, inconsistent W/SW swell building Thu, peaking Fri
• Strengthening N/NE tending late NW winds Thu with a building windswell on the Mid Coast
• Stormy W/SW swell Fri with strong W/SW-SW winds
• Moderate sized S/SW swell Sat with strong W-W/SW winds

Recap

The Mid Coast backed off to a slow 1-2ft yesterday while the South Coast was lumpy and bumpy to 2-3ft early, cleaning up through the morning as winds shifted more onshore ahead of sea breezes.

This morning, conditions were good early on the South Coast with a smaller swell, tiny on the Mid Coast. A strong onshore change has since moved in, writing off the surf for the day.

This weekend and next week (Dec 21 - 27)

Following today’s change, winds will swing S/SE into tomorrow and be fresh to strong as high pressure fills in from the west.

Swell wise, the South Coast will be small to tiny while the Mid Coast should see a small, inconsistent W/SW swell building into the afternoon, holding Sunday.

The source of this swell was a healthy frontal progression that moved from the south-west of Western Australia, under the country the past couple of days, with the remnants of it clipping the state today, bringing the onshore change.

Infrequent 1-2ft sets are likely on the favourable parts of the tide at the peak of the swell inside the gulf, while Middleton only looks to come in around 2-3ft or so.

Morning S/SE winds will again favour the Mid Coast on Sunday, shifting S/SW through the late morning and strengthening as the next swell generating system approaches.

This frontal system will project strong to sub-gale-force winds slowly up through our south-western swell window, with a moderate sized swell due to build through Monday and reach 3-4ft across Middleton but with fresh to strong S/SW-S winds.

The Mid Coast is only likely to see tiny 1-1.5ft waves and with less than ideal S-S/SW winds.

The swell is due to ease back through Tuesday and winds look to shift back around to the E/NE down South through the morning though it’s likely to be very peaky/lumpy with sets easing from 3ft+ across Middleton, tiny inside the gulf.

Christmas Day (Wednesday) is the pick of it as the swell drops further under a fresh N/NE breeze, tending variable ahead of weak, late sea breezes. Get in early for the most size as Middleton will ease back from 2ft on the sets.

Thursday is a tricky one as a deepening mid-latitude low moves in from the west, bringing strong N/NE winds that will shift even stronger NW near dark.

This will kick up building levels of windswell across the Mid Coast to 2ft+ later while a small to moderate sized, long-range W/SW swell is due to also build through the day.

The source is a strong but distant frontal progression that’s currently moving through the southern Indian Ocean. Any size on the Mid Coast will be overshadowed by localised windswell while the South Coast isn’t likely to get over 2-3ft into Thursday afternoon.

The low itself is expected to generate a large, stormy W/SW swell across the Mid Coast next Friday with moderate levels of swell for the South Coast along with strong to gale-force W-W/SW winds.

The weekend looks to possibly offer better waves as the low clears east and winds ease and tend locally offshore Sunday morning. More on this Monday though. Have a great weekend!