Victorian Surf Forecast (issued Wed 19th Feb)

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Craig started the topic in Wednesday, 19 Feb 2014 at 11:41am

Victoria Forecast by Craig Brokensha (issued Wednesday 19th February)

Best Days: Thursday and Friday morning on the Surf Coast, Sunday morning east of Melbourne, Monday and Tuesday mornings

Recap

Yesterday saw fun glassy waves across most regions during the morning with a light variable wind and 2ft of swell on the Surf Coast, and 2-3ft sets on the Mornington Peninsula. A shallow S/SW change moved in during the afternoon as the swell eased creating poor conditions.

Today the surf is tiny and clean on the Surf Coast, while the Mornington Peninsula had a touch more size but less than ideal conditions with a W'ly breeze.

This week (Feb 19 - 21)

First and foremost the swell due tomorrow and Friday has been upgraded significantly since Monday and winds are still looking good for the Surf Coast.

This is all the result of the deep low that's expected to form over Tassie this evening stalling slightly further west than initially forecast and being a touch stronger.

What we'll see through tomorrow will be a fetch of gale to nearly storm-force S/SW winds generated in our southerly swell window (above right) just off the south-west corner of Tassie along with strong to gale-force SW winds through Bass Strait.

A mix of localised SW windswell and stronger S/SW groundswell should develop through tomorrow with a peak expected either overnight or early Friday morning from the strongest 45-50kt S/SW winds tomorrow afternoon (bottom right).

This fetch will be right on the periphery of our swell window though with the swell squeezing between King Island and the North West Tasmanian coast.

In saying this tomorrow should still see large waves developing across the Victorian Coast, reaching 4-5ft+ across the Surf Coast into the afternoon with 6-8ft sets on the Mornington Peninsula.

Come early Friday we should still see 4-5ft waves early on the Surf Coast with larger surf east of Melbourne, but a steady drop in size is expected as the low moves off quickly across Tassie and out of our swell window Friday morning.

Now, as touched on in Monday's notes, winds move clock-wise around low pressure systems in the Southern Hemisphere but also tend inwards towards the low. This should help generate local offshore W/NW winds across the Surf Coast tomorrow morning, that may even persist into the afternoon, while Friday morning should again see offshores that will swing SW during the day as the low moves off to the west.

The Mornington Peninsula will unfortunately see poor W/SW winds with strength, with Western Port fairing the best as the swell kicks tomorrow afternoon and then eases Friday.

This weekend onwards (Feb 22nd onwards)

Give Saturday a miss as we'll see poor conditions with a moderate to fresh S'ly in the wake of the low and easing swell from Friday.

From Sunday onwards we'll see a mix of long-range and very inconsistent SW groundswell mixed in with some closer-range SW groundswell extending from a series of polar fronts pushing up behind the low responsible for the coming days swells.

Nothing above 2-3ft is expected along the Surf Coast through the early stages of next week, while the Mornington Peninsula should see more size to 4-5ft+.

Winds are looking a little funky with a weak troughy pattern expected across the region bringing light variable winds each morning ahead of localised sea breezes.

Harley32's picture
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Harley32 commented Wednesday, 19 Feb 2014 at 2:54pm

will there be a shadowing effect from king island on this swell, if so where will it effect?

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Craig's picture
Craig commented Wednesday, 19 Feb 2014 at 3:04pm

Great question.

It's hard to quantify but looking at King Island geographically it has a much greater effect in blocking westerly swells propagating through Bass Strait and on towards The Gippsland Coast and Flinders Island due to it's elongated north-south shape.

But when looking at a south or south-southwest swell the blocking land mass becomes much smaller and we'd probably not see much of an impact on the size across the Surf Coast as the swell refracts around either side of the island.

Without a comprehensive buoy and observational network it's also hard to analyse the impact King Island has or will have on swells from this direction, but any feed back from the coming days, especially later Thursday and early Friday from the Surf Coast region would be much appreciated.

mitchvg's picture
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mitchvg commented Thursday, 20 Feb 2014 at 3:10pm

In other words, you can't rummage around in the model script (cos it belongs to NOAA), isolate the shadowing parameter, and run a shadowless comparison?

thermalben's picture
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thermalben commented Thursday, 20 Feb 2014 at 3:15pm

We can do anything we want to the script. However you're over-simplifying things. It's a lot more complex than moving the 'shadowing parameter', per se - the model also takes into account bathymetry near the coast. So, you'd have to smooth out the bathy data near King Island to a point where the frictional effects were negligible.

And on top of that we'd have to run the model twice just to show the comparison (and running the model is not cheap).

As such, too much effort for what can be resolved more efficiently by improving the model resolution and input data.

carpetman's picture
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carpetman commented Thursday, 20 Feb 2014 at 4:51pm

CS buoy keeps rising, 5.8m sig & max of 9.5m, I assume this swell energy is directly mostly @ west coast tas & we'll mostly be cut off?

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Craig commented Thursday, 20 Feb 2014 at 4:57pm

In the initial notes (top of this post) I wrote that the strongest stage of the low would be this afternoon (also shown in the second picture). And this is why Sorell is still rising.

This will create the largest and strongest pulse of swell which will probably peak overnight/early tomorrow morning and will definitely still be in Vicco's swell window.

I'd be expecting 4-6ft waves tomorrow morning across the Surf Coast but a steady drop will be seen during the day as the low shifts across Tassie this evening.