Effective from: Fri 17 May '13, 01:17PM

Forecast prepared by Ben Matson.
Next update Mon 20/5 5pm.

Previous day's summary:

A small east swell and a light offshore breeze have maintained fun little waves across SE Qld over the last few days, with most locations coming in slightly bigger than forecast (just a half to one foot). Disappointingly, this is what was initially forecast on Monday - but when Wednesday morning's SE Qld surf reports came in slightly under expectation, I subsequently downgraded the following days (even though NSW reports were quite close). In hindsight I should have waited to issue Wednesday's forecast at the end of the day because the expected swell had started show by this time! Oh well...

Forecast period ahead:

The low developing in the lower Tasman Sea has thrown a few curveballs our way in the latest model runs, and as a result I'm going to slightly downgrade the outlook for the next four days (which was looking pretty small anyway).

The Tasman low is still expected to be quite broad in coverage, and slow moving in nature - both of which are ordinarily very good for East Coast swell prospects - however we're seeing an impediment creep into the synoptic charts, in the form of a ridge of high pressure south of the low (between Tasmania and Antarctica).

This is squeezing the low in such a way that the southerly extend of its western flank - the region that would ordinarily generate swell for us - expected to be focused less meridionally aligned (north-south) than previous model runs suggested. What this means is that rather than generating straight southerly swell for the region, the energy we see at the coast will have had to spread back towards the coast, which will result in a loss of size.

As it is, south swells usually have a difficult time rounding Cape Byron and (especially) Point Danger anyway. However in this case I think we're going to struggle to see much more than a foot of southerly swell across most Gold and Sunshine Coast beaches between Saturday and Monday.

Tuesday looks a little better, as a secondary south swell developing over the weekend is expected to make landfall, and it will have been generated a little closer to the Qld region and also a little further out into the Tasman Sea (which should improve its chances of refraction into the Gold and Sunshine Coasts, due to more S/SE in its direction). For my money, this will deliver the best waves of the forecast period.

Otherwise, you'll have to hit up a south swell magnet to extract the most size from this event. Saturday will see 1-2 waves at the exposed spots but Sunday and Monday should muscle up into the 2ft+ range. Tuesday should see another foot on top of this.

Looking further ahead and we have some exciting weather developments in store for mid-next week. There is good agreement across the models that an East Coast Low will form off the NSW South Coast sometime later Wednesday, leading to a significant swell event around Thursday and (more relative to SE Qld) Friday. Let's pin down the specifics in more detail on Monday.