Persistent S/SW swell for the entire forecast period

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Ben Matson (thermalben)

Victorian Surf Forecast by Ben Matson (issued Monday 19th May)

Best Days: Wed: fun waves with a new swell and mainly light variable winds. Fri: early good winds west of Torquay and a building S/SW swell. Sat/Sun: generally light variable winds and a fun S/SW swell.

Recap: Pumping waves all weekend in the 3ft range west of Melbourne, and 6ft east of Melbourne. Fresh NW winds most of the weekend in Torquay but they swung more N’ly east of Melbourne on Sunday. Smaller (but still) fun surf today with continuing offshore winds. 

This week (May 20-23)

*note: forecast notes will be somewhat brief this week as Craig is on leave*

We’ve got a reasonably fun week of waves ahead for the Surf Coast. After an extended period of quality groundswell (last week) with a lot of west in its direction, we’re now looking at around five or six days with more southerly orientation.

The source of this swell is a seemingly endless supply of fronts (I’ve previous used the word ‘conveyor belt’, which paints the right kind of picture) that are developing and still expected to develop midway between the ice shelf and Tasmania, stretching west to about 110E early in the forecast period, but generally doing most of its swell production east of 130E.

Now, this region is located right on the eastern periphery of Victoria’s swell window. Any further east and the resulting swell energy would be fully blocked by Tasmania, however in this case it seems that the fronts are developing with a reasonable amount of leeway. They're also spinning up over much of the same waters each time, continually working on the active sea state left by the previous front, which will allow the swell period to build up a little more than what we’d expect from a solitary front/low. 

And the value of the extra south in the swell direction can’t be overstated either. Typically, Torquay suffers quite a lot with regards to size attenuation, as swells refract around Cape Otway - losing anywhere between 30-70% of its size compared to (say) the Mornington Peninsula or Phillip Island, depending on just how much west there is in its direction. 

But with a SW thru’ S/SW swell event, wave heights often come in much closer across most central Victorian beaches and the extra southerly angle also allows for a slightly better wave shape off the Surf Coast reefs too.   

The only downside is that these fronts won’t be particularly strong, and they’re positioned quite a fair way from the mainland - so the resulting surf size won’t be large. But that’s actually a small blessing in disguise, because stronger fronts positioned a little more north in latitude would have an unfavourable bearing on our local winds. 

So the general consensus is for a building trend throughout Tuesday that should push 3ft+ in Torquay by the late afternoon and for much of Wednesday, with slightly bigger waves east of Melbourne (4-5ft). Early W/NW winds will swing to a late SW change on Tuesday but Wednesday’s looking very good with light variable winds swinging NE during the day - good for just about everywhere (there won’t be much strength in the local wind, so the Surf Coast reefs should remain clean).

A slight easing trend is expected through Thursday (down to an inconsistent 2ft+ on the Surf Coast) and early Friday ahead of a rebuilding trend on Friday afternoon that’ll hold through the weekend. Winds are looking OK for the Surf Coast during the end of the week but there’ll be a west component which won’t benefit the Peninsula or Island. SW winds may also develop in most areas on Friday as the associated front (generating the swell) passes across Tasmania but there should be a period of early W/NW winds in Torquay. 

This weekend (May 24-25)

Friday’s late arrival of S/SW swell is expected to hold through most of Saturday before easing slowly on Sunday. Surf size should reach somewhere in the 3ft+ range west of Melbourne with bigger 4-5ft waves east of Melbourne, and conditions are looking good both days with generally light variable winds Saturday tending light NE on Sunday

Longer term (May 26 onwards)

All of this S/SW activity is partly due to a major blocking pattern upstream, south of Western Australia that’s expected to persist all week. An amplifying long wave trough across the southern Indian Ocean throughout the forecast period looks like it’s only going to move slowly eastwards, and all of the models have a range of solutions for the Victorian swell window in the long term that incorporate a large cut off low in the Bight over the weekend and early next week.

These kinds of synoptic setups are often not a good thing for Victoria’s surf prospects, as the resulting swells tend to be aimed outside of Victoria’s swell windows (i.e. strong southerly swell into southern WA, and a strong westerly swell into SA) - but we’ll detail this more comprehensively in Wednesday and Friday’s updates.