Sydney Hunter Illawarra Forecast by Steve Shearer (issued Wed July 10th)

Features of the Forecast (tl;dr)

• Fun sized E/NE swell continues Thurs with mostly offshore/light winds
• E/NE swell filtering down from trough block at increasing levels from Fri , peaking Sat/Sun with freshening SW-S winds over the weekend
• Increase in short range S swell Sat PM, extending into Sun
• Temporary easing in size Mon 
• Renewal in E swell expected Tues, easing Wed
• Stronger S’ly swell expected Wed next week depending on position of low
• Plenty of S swell into the end of next week on a slow easing trend
• Another round of sizey S swell expected later next weekend as a cold outbreak pushes into our swell window

Recap

S’ly groundswell offered up some 3-4ft sets at S exposed breaks yesterday with clean morning conditions. By the a’noon more E’ly angled swells started to fill in and this morning there is some very nice looking 3ft surf out of the E-E/NE with offshore winds under sunny skies. Plenty more to come as a mid-winter trough block pattern sets up and comes to fruition.

Nice and crisp on the beachies this morning

This week (July 10-12)

A trough is currently clearing the coast, expected to anchor a broad E’ly fetch generated by a monster high straddling New Zealand. This anchored trough fetch, or trough block pattern is favourable for swell production for almost the entire Eastern Seaboard and will come with mostly offshore winds until the weekend brings a more S’ly biased flow to temperate NSW. We’ll see remnants of a small low at the terminus of the trough get captured next week and generate S swells from the return flow of a regenerated low. Those swells are still looking a bit tricky to call as the new low ducks back in close to or behind Tasmania. We’ll sketch it out now and revisit details Fri.

In the short run and the current signal of E/NE swell hangs in the 3ft range with offshore W-W/NW winds and an a’noon variable tending light N-NE seabreeze.

Similar size Fri morning. Winds will shift Fri as a circulation forms in the trough line. We should see offshore W-W/NW winds, possible with a period of NW breezes before winds shift SW-S in the a’noon. That SW-S shift looks to occur just after lunch on the Illawarra, later mid a’noon in Sydney so factor that in for the after work surf. We will see a muscling up in size Fri a’noon, as a prelude to a stronger increase over the weekend as windspeeds intensify into the circulation in the trough line (see below). Size should push up into the 3-4 occ. 5ft range by close of play. 

This weekend (July 13-14)

We get a size upgrade over the weekend as a result of gales feeding into the circulation Fri. That would suggest a stronger, longer period E-E/NE swell with 6ft sets, possibly bigger at E facing magnets. Pumping in other words. You will have to factor in the wind though. It looks like a significant S’ly flow will establish around the circulation/surface low forming in the trough line. Early W/SW winds will quickly shift SW then S/SW at mod/fresh paces. That local fetch will generate a spike in short range S swell building to 3-4ft in the a’noon. Plenty of swell energy but the favourable E/NE direction from the dominant swell should be lighting up plenty of sheltered corners.

An energetic mix of S and E/NE swell continues into Sun. We’ll see the E/NE swell come off the boil, with size to 4-5ft easing during the day and short range S swell to 4-5ft. Early SW winds should tend more W’ly north of the Harbour and this winds will swing again to the S/SW-S during the day, though at lighter paces than Sat. 

Next week (July 15 onwards)

Bit of a tricky outlook for next week. Looks like the trough block fetch re-energises close to the North Island late in the weekend into Mon (see below). That should give us one last pulse of E’ly swell filling in on the declining swell from that direction. We should see that pulse Tues, back up into the 3-4 occ. 5ft range under W-SW tending SW-S winds.

Mon looks to stabilise in the 3-4ft range with winds shifting offshore as the low formed over the weekend drifts SW back towards Tasmania. 

Depending on the position of the low early next week we’ll be up for a stronger pulse of S swell generated by gales around the western flank of the low. That should see surf rebuild from the S Wed into the 5-6ft range. Expect revision to these estimates on Fri once we get a clearer picture of how that low will behave as it meanders around in the lower Tasman.

Broadly speaking surf should slowly come down from that peak later next week. 

We may see a strong new low/frontal progression linked to a cold outbreak push into the Tasman late next week (see below). Under this scenario we’d expect more strong S swell later next weekend. Plenty of action ahead so check in Friday for the latest updates.

Seeya then.