Effective from: Mon 20 May '13, 12:23PM

Forecast prepared by Ben Matson.
Next update Wed 22/5 5pm.

Previous day's summary:

A pumping south swell delivered a wide range in wave heights over the weekend across southern NSW beaches. The Hunter coast saw the biggest surf with 4-6ft waves early Saturday easing a touch on Sunday, whilst exposed south facing beaches in Sydney saw 3-4ft surf for much of the weekend. Wave heights were smaller south of about Wollongong due to the source of the swell. Conditions were clean all weekend with moderate W/SW winds.

The swell has kicked a notch this morning owing to a secondary pulse of swell from the same parent system, with south facing beaches in Sydney are holding 3-5ft (interestingly, Newcastle was only 4ft this morning but is building and should reach 5-6ft this afternoon). Conditions are still very clean thanks to a persistent W/SW breeze.

Forecast period ahead:

We're currently right at the peak of this extended south swell event, and wave heights will start to taper off during Tuesday. But, solid waves are still likely in the morning - mainly at south facing beaches, and as per the last few days we'll see the largest surf in the Hunter. Conditions will remain clean with offshore winds.

The low responsible for this south swell is now moving over to NZ longitudes and although it is weakening, it'll still continue to generate swell for the middle of this week. You will need to surf early on Wednesday though, as morning offshore winds will give way to an onshore airstream after lunch as a weak trough moves off the coast and a high ridges in from the south.

From here on in the second half of the week becomes quite dynamic, with the development of an East Coast Low off the coast on Thursday.

Now, to be perfectly honest, I don't really like the look of the surf potential from this system. Sure - we're going to see a lot of swell from it (somewhere in the 6ft+ range on Friday) but it's going to be wet and windy with gusty sou'easters - and short range swells like this often don't do much more than provide small clean waves at protected spots, and rearrange the banks at the open beaches.

Right now it looks like the low will move slowly to the east, directing a strong SE airstream along the North Coast (great for SE Qld this weekend!) but I'm going to reserve my judgement for anything worthwhile in southern NSW until Wednesday's forecast. At this stage the weekend is 50/50 as winds are most ikely going to be fresh southerly, however it's posisble that local topographical influences could steer this flow around to the SW at some spots in the mornings.

Looking further ahead, and a strong front is expected to track below Tasmania and up into the Tasman Sea around Sunday, which would being about a solid southerly groundswell for late Monday and Tuesday next week. Let's look at the specifics in more detail in Wednesday's update.