Victoria Forecast by Craig Brokensha (issued Friday 21st February)
Best Days: Early Saturday on the Surf Coast, every other morning with light winds and plenty of swell
We're now on the backside of a very tricky and rare S/SW groundswell event from a stalling mid-latitude just west of Tassie the last couple of days.
This low stalled within our swell window yesterday, aiming a fetch of gale to storm-force S'ly winds towards us (satellite wind observations pictured below), generating a large pulse of S/SW groundswell mixed in with some localised SW windswell.
A peak to 4-6ft was seen across the Surf Coast with fresh to strong W/NW winds favouring the protected reefs, offering the biggest and best day of surf in months west of Melbourne.
East of Melbourne the open beaches were out of control but protected spots such as Western Port offered small clean waves.
The largest pulse of S/SW groundswell likely peaked overnight, with Cape Sorell reaching a peak a couple of hours before mid-night with Significant Wave Heights of just under 8m and Maximum Wave Heights of just over 11m.
There would have been a lot of windswell contamination in those readings though, confirmed by the Average Period readings of 8-9 seconds and 50kt+ W/SW wind gusts at the Cape Sorell automated weather station.
Still this morning there were waves in the 4-5ft range on the Surf Coast, with 6-8ft sets on the Mornington Peninsula with early W'ly winds that are now starting to move onshore with the low responsible for the swell shifting off to the east.
This weekend onwards (Feb 22 onwards)
The swell from the low will continue to dip into tomorrow and conditions will be poor across all spots with a SW breeze, but the Surf Coast is now looking better early with a light W'ly expected to create cleaner conditions.
Moving into Sunday we'll see the first of a series of good SW groundswell pulses filling in across the coast, generated by a conveyer belt of polar frontal activity in the Southern Ocean being aimed up towards Tassie all owing to the Long Wave Trough.
The Long Wave Trough is basically an upper atmospheric wave that focusses storm activity into a certain region, and can have up to five regions of amplification. One of these amplifications is expected to move in from the west and intensify across south-eastern Australia next week, directing polar fronts up through our swell window.
The first system is currently developing south-west of us and will push up towards Tassie during today and tomorrow morning while generating a fetch of W/SW-SW gales.
Once this system moves out of our swell window below Tassie another polar front will quickly move in behind it, producing a pre-frontal fetch of W/NW winds followed by SW gales while approaching Tassie on Sunday.
This will be over an already active sea state, and while the system won't be as strong, should still generate a reinforcing increase in SW groundswell for Monday keeping 3ft+ sets hitting the Surf Coast and larger 6ft+ waves on the Mornington Peninsula.
A slight break in polar frontal activity after Sunday's system will result in a slight drop through Tuesday afternoon before we see yet another two polar fronts firing up towards us, producing a larger increase in SW groundswell for Thursday afternoon/Friday morning.
Rewinding a bit, the winds in general will be light and variable each morning from Sunday through Tuesday but possibly lingering onshore as a weak surface trough sits across us. So don't expect perfectly clean conditions, but more so lumpy/wobbly surf that may be bumpy at times with weak bursts of onshores.
Longer term our run of swell will dry up into next weekend as the Long Wave Trough moves off to the east and a strong blocking high moves in from the west. So make the most of the coming period of waves.