SWELL ALERT: Huge South Swell Looms for the Entire East Coast

20 Aug 2019 9 Share

Ben Macartney

Chief Surf Forecaster

Issued Tuesday, 20 August 2019

To date, surfers across the NSW coast have had it pretty good this month; benefiting from a good to excellent run of winter conditions; characterised by a consistent, mid-sized south and SSE swells - for the most part groomed by offshore winds. However, it’s now clear this long-lasting run of idyllic conditions will quickly come to a (temporary) close later this week, following the development of an intense, slow-moving low pressure system over the southern Tasman Sea.


All sorts of good options will open up as the swell and wind backs off throughout Friday. Photo: Uploaded to CW by Dan Bielich.

All sorts of good options will open up as the swell and wind backs off throughout Friday. Photo: Uploaded to CW by Dan Bielich.

As the developing low moves clear of Tasmania early on Wednesday we’ll see a broad 35 to 45kt SW fetch expanding east of Tasmania and Bass Strait, and throughout the southern Tasman Sea. That will trigger a large and energetic increase in southerly groundswell; starting to show across the South Coast on Wednesday afternoon before really kicking in size across Sydney and Newcastle on Thursday morning. However, the catalyst for the phenomenal spike in height and period forecast for Thursday afternoon through Friday morning is linked to another vigorous front feeding into low’s south-western sector on Thursday morning.

The early stages of the low's impact get underway as it shifts clear of Tasmania and Bass Strait on Wednesday morning. Source: BOM.

The early stages of the low's impact get underway as it shifts clear of Tasmania and Bass Strait on Wednesday morning. Source: BOM.

The front’s south to north progression, parallel to the southern NSW coast, invigorates another powerful 35 to 45kt plus SW to SSW fetch area; originating out of eastern Bass Strait and extending northeast into the southern Tasman Sea. Keep in mind these winds will go to work upon an already highly energetic sea-state whipped up by the early stages of low’s development – and this will accelerate the growth over the top of an already heavy sea-state.

An embedded front feeding into the low's western flank generates a second surge in SSW gales, elongating out of eastern Bass Strait on Thursday morning. Source: BOM.

An embedded front feeding into the low's western flank generates a second surge in SSW gales, elongating out of eastern Bass Strait on Thursday morning. Source: BOM.

That means leaves little doubt we’re in for a monster South storm-swell; conservatively reaching 10 to 12ft+ across southern exposures, with scope for even larger surf off deepwater reefs as the swell peaks under fresh SSW winds across Sydney and surrounds on Thursday afternoon. However, this relatively close range fetch belies a much broader SW/SSW fetch surrounding the low’s south-western quadrant, below Tasmania on Wednesday and Thursday. This longer-range source will produce another full day of large/ heavy conditions on Friday as swell direction slowly reorients from south to SSE.

Recent model runs show the impact of the low coming to a head across the southern half of the NSW coast on Thursday afternoon. Source: BOM.

Recent model runs show the impact of the low coming to a head across the southern half of the NSW coast on Thursday afternoon. Source: BOM.

It won’t be until Saturday morning that we’ll really see more accessible – not to mention high quality surfing options opening up across exposed areas. The odds are pretty high for clean surf, ranging anywhere from 3 to 6ft across exposed areas between Newcastle and Ulludulla, groomed by light offshore WNW winds.

Thursday's heavy South-spike gives way to rapidly improving conditions as both swell and wind ease throughout Friday and Saturday. Source: Wave Tracker.

Thursday's heavy South-spike gives way to rapidly improving conditions as both swell and wind ease throughout Friday and Saturday. Source: Wave Tracker.

Sydney and The South Coast: Where to Surf
The rapid transformation in conditions setting in throughout Thursday will quickly cancel out surfing across exposed areas. As the swell builds into the afternoon under strong SSW winds your options will continue to diminish; becoming limited to the most sheltered southern corners (such as the south end of Manly and Collaroy on the northern beaches). However, it’s starting to look like a wider range of options will open up on Friday as rapidly easing WSW to SW winds drop to light and variable, then light SE to NE during the afternoon. That should see all sorts of good big-wave options on Friday morning, with more exposed reefs coming into play as the swell begins to settle and become better organised throughout the afternoon.

In summary

Thursday
Large/ heavy South swell rises steeply throughout the day. Possibly undersized at 5 to 6ft+ near dawn, picking up to 6 to 8ft+ across south facing beaches in the morning, into the 8 to 10ft+ range during the day and peaking at 10 to 12ft+ in the afternoon – bigger on offshore reefs. Wrapping at lower levels elsewhere with size depending on exposure. WIND: Early Westerly, tending WSW 15 to 25 knots in the morning, then SW 20 to 30 knots during the day and SSW to Southerly 25 to 35 knots into the afternoon.

Friday
Easing SSE groundswell. Around 8 to 10ft across south facing beaches early, settling to 6 to 8ft+ during the afternoon. Wrapping at 3 to 8ft levels along elsewhere with size depending on exposure. WIND: WSW to SW 10 to 15 knots, tending variable during the day, then lighter E to NNE during the afternoon.

Saturday
Easing SSE swell around 3 to 5ft+ early, easing to 2 to 4ft later. Wrapping at lower levels along open beaches with size depending on exposure. WIND: WNW to NW 5 to 15 knots, tending light and variable, to light sea-breezes in the afternoon.


Tags: SWELL ALERT , Ben Macartney , topnews (create Alert from these tags)

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