Effective from: Mon 20 May '13, 01:11PM

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

Previous day's summary:

It's been a mixed weekend across the North Coast thanks to a directional south swell. Some exposed swell magnets saw set waves pushing 3-4ft+ at times, other open beaches saw very little size, and protected spots remained tiny. Conditions were however clean with offshore winds. For reference, the Hunter and Sydney regions saw pumping waves all weekend, up to 4ft in Sydney and 6ft in Newcastle.

A secondary pulse in south swell is building along the coast (it reached Sydney this morning) and is due to arrive across most North Coast locations by the end of the day ahead of an overnight peak in size and a slow downwards trend on Tuesday.

Forecast period ahead:

The renewal of south swell due later today should provide great waves for most locations on Tuesday. The swell direction should swing more to the S/SE, which should allow a slightly greater penetration across North Coast surf spots than what we saw over the weekend, and conditions should remain clean with light 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. Light variable winds are expected for most of Wednesday so great waves - albeit smaller than Tuesday - should be found at most open beaches.

From here on in the second half of the week becomes quite dynamic, with the development of an East Coast Low off NSW coast on Thursday (in the vicinity of Seal Rocks).

Initially, this low will not be favourably positioned for the North Coast. Whilst computer models are in agreement about the position and size of the low, they are in disagreement as to the structure of the low, and its corresponding surface wind field. We may see some radial spread of E/SE swell across the lower Mid North Coast on Friday with a kick in short range S/SE swell through Saturday as the low drifts away from the coast, however the US model delays these developments considerably, so much so that the first major swell increase would happen later Saturday, with a more prominent increase for Sunday. We'll have more confidence on this over the coming days as the models tighten up.

In any case, 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 5-6ft+ range at south facing beaches at some point over the weekend) but it's going to be wet and very windy. The only locations likely to benefit from this scenario are the points, and they'll be quite degree smaller due to the strong southerly component in the swell direction.

Nevertheless, this is certainly a significant weather system so let's check back on Wednesday to see what's changed in the model output.

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 Tuesday next week. Let's look at the specifics in more detail in Wednesday's update.