Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Fri Sep 20th)

Features of the Forecast (tl;dr)

• S swell lingering into Sat AM before easing
• A few small S swells at S facing beaches Sun
• More offshore winds this weekend 
• Small boost in size Mon with offshore winds tending NE
• NE windswell on the radar Wed
• S groundswell Wed next week
• Stronger front/trough in the Tasman mid week suggests sizier S swell Thurs/Fri next week
• Potential for surface low in Tasman late next week with days of of SE swell- check back Mon for latest revisions

Recap

 S groundswells to 3-4ft yesteerday eased in the a'noon with light W winds tending NW in the a’noon. Today has eased back to 3ft with offshore W’ly winds. tending variable then W/NW in the a'noon. A fresh pulse of S swell is now supplying 4-5ft sets at S facing beaches. A nice run of S swells and offshore winds.

Nice lines of S swell yesterday under offshore winds

This weekend (Sep21-22)

No change to the wind outlook for the weekend- zonal fronts and weak high pressure to the west and well out in the Coral Sea supply W’ly-W/NW’ly winds both days with only late, light seabreezes on offer (if at all).

Doesn’t look we’ll see much swell of significance from these zonal fronts so expect small swells from the S over the weekend, only really favouring S swell magnets.

Sat morning should see some 2 occ. 3ft surf at S swell magnets with a mix of mid period and traces of long period energy. Expect tiny surf away from S facing beaches. Mid period swell looks to drop out after lunch so expect long waits for sets.

Another minor flush of mid period S swell Sun keeps S facing beaches in that 2 occ. 3ft range again with tiny surf elsewhere.

Next week (Sep23 onwards)

Similar winds for Mon with another front pushing through Bass Strait Sun into Mon and bringing a W’ly flow up through temperate NSW. Again, just a small flush of mid period directional S swell pushing up the coast, likely favouring areas from Syd to the Hunter in the 2 occ. 3ft range Mon. Tiny elsewhere.

We’ll see high pressure start to occupy the Tasman early next week with a developing N’ly flow through Tues. Small S swell leftovers Tues in the 1-2ft range.
By Wed that N’ly flow start to look robust enough to generate some workable NE windswell , likely building to 2-3ft in the a’noon. Underneath that NE windswell should be some small S’ly groundswell from a mobile but deep low tracking through the lower Tasman (see below). Some 3ft sets are likely form that source. An approaching trough does offer potential for a window of NW-W winds later in the a’noon. We’ll finesse the timing of those winds on Mon but worth flagging for now.

The trough then brings a more dynamic pattern into the second half of next week. We should seee early offshore winds Thurs with a mix of NE and S swells to 2-3ft. From there the trough deepens and moves Northwards, backed by a strong front in the lower Tasman and a large high in the Bight. The combination of those elements strongly suggests a strong surge in S swell Thurs, with freshening SW-S winds. We’ll pencil in a build to 5-6ft Thurs PM and see how it looks on Mon.

More strong S swell into Fri.

Model divergence reduces confidence in the outlook with GFS suggesting the trough deepens into a broad surface low (see below) which would bring days of elevated S through SE-E/SE swell and onshore winds.

ECMWF prognosis features a less dynamic outlook with the trough moving north and dissipating into the end of the week with the high pressure dominating the Tasman by the weekend, bringing an E tending strong NE flow through this period.

We’ll flag a dynamic outlook for later next week and see how it looks on Mon.

Seeya then and have a great weekend!