Southern Tasmania Forecast by Ben Matson (issued Wednesday May 5th)

Features of the Forecast (tl;dr)

• Strong, easing swell from Thurs AM into Fri
• Improving conditions Thurs, light variable winds Fri onwards
• Small new swell Sat (w/ light winds)
• Bigger S/SW swell Sun (w/ light winds)
• Small new swell Tues and Thurs
• Chance for a solid swell next weekend

Recap

Nice waves across the South Arm for the last few days with NW thru W winds creating decent conditions at many beaches and size holding 2-3ft, slightly above forecast expectations.   

South Straddie Cliffy this afternoon

This week (May 8 - 9)

Wave heights should maintain size through Thursday, and conditions will improve as overnight W’ly winds swing back around to the NW. Exposed spots may have some leftover surface bump and wobble early morning but it’ll get better by lunchtime and the afternoon’s looking fun for a wave. 

Expect size to hold in the 2-3ft range, becoming smaller after lunch.

Light variable winds will then allow much cleaner conditions to settle for Friday with smaller residual swells in the 2ft range. It'll be well worth a surf both days, just keep your expectations in check for the early session Thursday in case the overnight breeze creates a few issues on the surface. 

Late Friday may see the arrival of a small reinforcing groundswell originating from a broad pre-frontal W/NW fetch developing in the Southern Ocean now, below Western Australia.

Even though the fetch is poorly aligned, it is quite broad, long and strong, and will be working on the active pre-existing sea state from the current frontal progression, which should assist swell generation. 

This should boost surf size a little more though we’re more likely to see a peak from this source into Saturday.

This weekend (May 10 - 11) 

The aforementioned reinforcing pulse for Saturday will be accompanied with light variable winds so we’re looking at some fun peaky waves around the 2ft+ mark. Size is expected to ease through the day though, and the swell won’t be very consistent, so aim for the morning.

On Sunday, we’re still on target to see a new S/SW swell from a polar low developing at the tail end of the fetch responsible for the late Fri/Sat pulse. I like the direction of this swell a little more for the South Arm, though the polar low will only sit in the swell window for a short period of time so this event may only show for a brief period of time. 

Fortunately, local winds look to be light and variable again so conditions will be clean, and size should pulse into the 3ft+ range through the middle of the day.

Either way the weekend’s looking fun both days but Sunday is my pick overall. 

Next week (May 12 onwards)

Smaller, residual swells will pad out the start of next week, but we have a few new swells due through the week that will keep the South Arm flush with small waves. 

Later Monday and early Tuesday, a new long period swell may reach the coast, generated by a small but tight low passing near Heard Island tomorrow. However the small fetch length and enormous travel distance means it probably won’t eventuate in much size throughout Victoria. The only reason it’s worth mentioning is because with locally light winds and a lack of significant pre-existing swells, it’ll probably be noticeable at the wave buoys with a jump in peak period to 18+ seconds - so my point is, don’t get excited about it. 

However, a slightly better swell generated by the latter stages of this low (passing under Australia on Sunday and Monday) will generate a better SW tending S/SW swell for Tuesday that could produce some reasonable 2ft sets across the South Arm, before easing into Wednesday. I'll take a closer look at this on Friday. 

Thursday onwards is where things start to become more interesting.

Another strong conveyor belt of Southern Ocean fronts will develop around Heard Island on Sunday and move through our swell window, but this time they’ll strengthen closer to the mainland - unfortunately a little more westerly in alignment than is ideal, but probably strong enough to override some of these directional deficiencies. 

This is expected to generate a new swell for the region on Thursday around 2ft+. 

We’re then looking an amplification of the Long Wave Trough into next weekend that’s on track to deliver a very large swell across the entire region, if current model guidance holds true (see below) we could be looking at some sizeable surf across exposed Tasmanian coasts (which ones though… west, or south?).

Of course, this is all still a very long time away. So let's be cautious for now with our expectations, but pencil it into the diary. 

I’ll have more on that in Friday’s update. See you then!