Southern Tasmanian Forecast by Ben Matson (issued Monday March 10th)

Features of the Forecast (tl;dr)

• New groundswell for Tues but E/NE winds will spoil surf conditions
• Small leftovers Wed/Thurs AM
• New swell for Thurs PM, looking best Fri AM with light winds
• Smaller surf Sat with good winds
• New long period groundswell building Sunday, best conditions early
• Stacks of swell for next week

Recap

It’s been tiny and clean all weekend and this morning, up until early afternoon today when a gusty southerly change arrived. A small increase in windswell (with a minor new groundswell) has lifted surf size later today though quality is poor.

This week (Mar 11 - 14)

The leading edge of a new long period groundswell reached Cape Sorell around lunchtime today, and will build towards a peak on Tuesday. 

However, not only is very little size expected from this source - maybe 1-2ft tops - this afternoon’s southerly winds will swing around to the E/NE overnight, maintaining average conditions (tending poor as it strengthens) across the South Arm. Though, locations east of the Pittwater estuary will offer better conditions under this wind regime.

Wednesday and early Thursday will then see a return to very small conditions as winds swing to the north. 

However, during Thursday day we’ll see some new long period swell reach the Cape Sorell buoy that will show across the South Arm into the afternoon and early Friday. 

This energy will be generated by a slow moving polar low well to the SW of Western Australia at the moment, in an ideally angled - if somewhat distant - region of our swell window (see below).

Thursday afternoon is at risk of an accompanying (though unrelated) SW change as a front clips the coast, but Friday morning is looking fun with inconsistent 2ft sets possible at the South Arm swell magnets and lighter winds. 

As such, Friday is the pick of the working week but late Thursday could have some options if the models change the strength and timing of the change.

This weekend (Mar 15 - 16)

A series of powerful fronts pushing through the Southern Ocean this week will setup an overlapping sequence of SW groundswells that'll arrive during the weekend.

At this stage, Saturday looks to start off with small leftovers from Friday though we could see a minor reinforcement of mid-range swell from a pre-frontal W/NW fetch (this may lift the inconsistent baseline 1ft surf a touch). Local winds should be N’ly so conditions will be clean.

However Sunday is where we’ll see a strong building trend, up into the 3ft+ range by the afternoon though winds may again veer SW behind another cold front.

Let’s fine tune the specifics on Wednesday.

Next week (Mar 17 onwards)

All signs are pointing towards an extended run of strong Southern Ocean fronts into next week (i.e. with a negative SAM), which suggests a decent spell of elevated wave heights along the southern Tasmanian coast. It’s early days for now, but a very promising run of Autumn swell looks imminent.