Extended run of small surf ahead

South Arm Surf Forecast by Ben Matson (issued Thursday 14th March)

Best Days: No great days, but there'll be small beachies around the traps. Keep an eye out for a small flukey pulse of swell late Sunday too.

Recap: Tuesday saw small surf initially ahead of a late kick in size behind fresh to strong W’ly winds that reached gusts of 41kts at Bruny Island. Solid swells built on Wednesday with rapidly easing winds that became light and variable through the day. Wave heights are now easing steadily and winds are around to the north.

This week and weekend (Mar 15 - 17)

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*this week's Forecaster Notes will be occasionally brief and erratic, as Craig is on annual leave - they’ll be updated Tues/Thurs/Sun - to receive notification when they’re updated, please update your account preferences*

A small cut-off low approaching from the west is expected to renew swell into Friday, though it’s very west in direction and the models have slightly weakened it since Tuesday’s notes were prepared. We’re also no longer expecting a brief intensification of S’ly winds as it tracks under Tasmania. 

As such we’re looking at small surf to finish the week. Winds will swing W/SW in the wake of the front passing to the south but there won’t be a lot of strength in it (most of the wind will be south of Storm Bay) and there’ll be periods of variable winds at times across the South Arm.

The weekend’s looking generally uninteresting in the surf department, with small residual swells and mainly light to moderate NE winds. 

In Tuesday’s notes, I mentioned an intensifying polar low well below WA for Friday that had the possibility of generating a small unusual sideband SW swell for Sunday afternoon. The models still suggest this will happen though I’m not as keen on this following analysis of the surface charts;  its a flukey system that’s aimed poorly within our swell window, and these kinds of swells often have difficulty diffracting back into sheltered bays and often only glance exposed beaches.

Still, it’ll be worth keeping an eye out for a possible pulse of small swell on Sunday afternoon, particularly if you can get yourself to a beach with more westerly exposure than the South Arm. It won’t really provide much until late in the day though.

Next week (Mar 18 onwards)

A blocking synoptic pattern will maintain light winds across the region for most of next week.

Although no major swell activity is expected until the end of next week and the weekend, a seemingly endless supply of reasonably strong Southern Ocean lows will move track parallel to the ice shelf all week, supplying pulsey groundswell for our region.

The low latitude of the storm track (i.e. along the ice shelf) is much more favourable than what we’ve seen recently, as it’ll be better positioned within our swell window. Though the large travel distance will erode a considerable percentage of size. 

This should produce small fluctuating swells for the South Arm all week in the 1-2ft range, and embedded pulses within this pattern (currently late Mon/Tues, Fri and Sun) should punch another foot or so higher than this too (later next week has the potential for a low more size from local sources too, but more on that in Sunday’s update).


uncle-swap's picture
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uncle-swap commented Tuesday, 19 Mar 2019 at 3:39pm

Just checking when the next updated forecast will be happening?
Many thanks team :)


thermalben's picture
thermalben's picture
thermalben commented Tuesday, 19 Mar 2019 at 3:40pm

I'll have one later this afternoon. Sorry for the delay! Will also have the East Coast forecast updated too.

uncle-swap's picture
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uncle-swap commented Wednesday, 20 Mar 2019 at 8:55am

Thanks Ben! Appreciate these detailed forecasts :)