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A new southerly swell to impact the NSW coast

Felix Levesque, Sunday May 31, 2020 - 12:15 AEST

As beaches across the NSW coast slowly recover from the large, powerful and prolonged beating last weekend, the Tasman Sea prepares to stir up again and send significant energy to our shores.

Last weekend saw a Tasman Low deepen off the southern coast of NSW. Significant wave heights off the coast of Sydney quickly ramped up to 5m and remained in the 4-6m range for a prolonged period of 4 days from Friday May 22nd extending to the end of Monday 25th. Maximum wave heights also reached a staggering 11.59m in the late afternoon of Sunday 24th. Wave height easily reached 10-12 feet at beaches exposed to the south. This brought about significant erosion across exposed beaches (dozens of metres of beach washed away into the surf), and pounding surf for only experienced surfers.

A trough and cold front currently pushing across the Southern Ocean may deepen into another low pressure system over the Tasman Sea this week. Uncertainties around this system are still fairly high, especially when considering what it will do as it reaches the waters off the NSW South Coast. Regardless of the different models and iterations, a significant pulse in southerly swell is expected around the middle of the week.

Current model runs suggest an initial burst of lower period swell, around 2-3m in height during the afternoon of Tuesday June 2nd. A fetch of south-southwesterly winds off the southern coast of NSW will bring surf pushing the 5-6ft range in Sydney by afternoon. Winds will also be mostly west-southwesterly, providing good conditions for experienced boardriders. Conditions should also hold going into Wednesday, especially early.

Figure: Significant wave height contours with wind barbs showing an initial, lower period swell generated by gusty south-southwesterly winds off the southern NSW coast on Tuesday afternoon.

An intense fetch of southwesterly winds to the east of Tasmania as this system crosses into the Tasman Sea will generate a second, more sizable and intense swell. By the early hours of Thursday this week, waves off the coast of Sydney look to reach the 4m mark, and gradually easing and halving in size into Friday. The surf at exposed spots may push into the 6ft and high range, with offshore reefs seeing even greater size. Winds may be an issue as they tend from southwesterly in the morning to southerly throughout Thursday, but light winds on Friday should bring excellent conditions for experienced surf riders.

Figures: Significant wave height contours with wind barbs showing a more significant, larger swell generated across the Tasman Sea throughout Wednesday to impact Sydney (and coasts further north) late on Wednesday, peaking early on Thursday and easing into Friday.

It is unlikely that this system will produce waves anywhere near the size of those brought by the system last week, but powerful surf should still present itself, so surfers should keep their step-up and, possibly, gun surfboards handy for the coming week.

- Weatherzone

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