Long period S swell pulses ahead before a windy weekend
Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Wed Sep 22)
Forecast Summary (tl;dr)
- Mix of easing S swell Thurs with some small, longer period S swell and light winds and a'noon seabreezes
- Stronger long period S swell Fri with clean conditions early and a NW flow PM
- Small long period S swell Sat with a window of good winds early before fresh S'ly winds
- Stronger mid period pulse Sun, hampered by S to SE winds.
- Residual S swell Mon, with light morning winds
- NE windswell potential from Tues PM, likely peaking Thurs, stay tuned for details
Wild and wooly weather and a local, directional S swell have been on the menu since Mon. Yesterday was mostly poor quality 3-4ft surf, bigger 4-5ft on the Hunter with strong S’lies hampering surface conditions and restricting surfable locations to protected locations. Winds eased enough overnight for a brief window of offshore winds which allowed some cleaner surf in the 3-5ft range to be utilised but S’ly winds have now confined surfing to more protected spots where size is in the 2-3ft range. The trend from here will be moderating winds and swell, details below.
This week (Sep 22-24)
We’re now past the peak of the spike in directional S swell generated by an intense front. Synoptically, a weak 1000 hPa low is now near the North Island, with a dominant 1033 hPa high north in the Bight beginning to drift into the interior and weaken. Pressure squeeze between these two systems is expected to rapidly weaken over the next 12-24 hrs, leading to an easing in both wind and swell. Below the continent, a very active Southern storm track is generating large seas with a few pulses of long period swell expected from this source.
With the high rapidly pinching off from the interior and moving into the Tasman tomorrow winds will quickly shift back to the northern quadrant, with a morning W to WNW breeze shifting NW before synoptic frontal winds shift more WNW again in the a’noon. That will make for excellent conditions to mop up the easing S swell from the current event. Expect clean 3ft surf across S facing beaches in the Sydney region, with larger 3-4ft surf in the Hunter, possibly with some early 5ft sets. Some longer period S swells in the a’noon coming from the Southern Ocean are likely to see some 2-3ft sets across S facing beaches through the region, more notable at spots that focus longer period swells.
Friday is a better bet for long period S swells. Expect some extra grunt in the sets as 16-18 second period S swells radiate in from a deep southern source fetch. A Bass Strait fetch of low end W’ly gales Thursday will put smaller S swell into the mix as well. W/NW winds continue through the morning before tending N to NW in the a’noon so there’ll be plenty of scope for S facing beaches and magnets to utilise the swell. Early 2-3ft sets, should build into the 3ft+ range across the region with scope for select S swell magnets and the Hunter coast to pick up strong 4ft sets through the a’noon.
This weekend (Sep 25-26)
Still a fair whack of S swell on the cards for this weekend, but only Saturday morning has fair winds. A deep low passes to the south of Tasmania Friday, with a window of W’ly component winds on offer Saturday morning, before a new high pressure ridge rapidly builds in behind the change. Unfortunately the morning session will likely be a bit undersized as long period S swells wane and the new S swell generated by the passage of the front into the lower Tasman arrives behind the wind. Worth the early start Sat for clean 3ft sets, 3-4ft on the Hunter, easing back before winds tend fresh S’ly and S’ly swell builds again with a mix of short period local S’ly swell and mid period sources into the 4ft range. Fresh S’ly winds will mean sacrificing plenty of that size to find some quality.
Sunday has plenty of S swell on offer, generated by the front and fetch of severe gales as it transits the lower Tasman overnight Fri into Sat morning. Morning size in the 4-6ft range at S facing beaches on the Hunter, grading smaller 3-5ft through the Sydney region and regions south is expected to ease slowly through the day. Only the early morning window looks a chance for a morning SW breeze, with the ridge along the coast generating a fresh S’ly flow, that will tend SE through the day. Smaller surf in more protected bays will offer cleaner options through the day. An easing in wind in the a’noon is likely as the ridge slackens but expect exposed beaches to still have plenty of lump and bump.
Next week (Sep 27) and beyond
High pressure dominates the Tasman for the first half of next week, at least, with an easing of the intense frontal activity below Australia leading to a suppression of the S swell window, although there are plenty of leftovers for Mon, easing into Tuesday.
Residual S swell trains Monday are likely to see 3-4ft surf at S facing beaches, bigger 4ft on the Hunter and easing through the day. With high pressure drifting east into the Tasman over Central NSW later Sun into Mon a period of light morning winds is likely before winds tend to the N and freshen during the day.
Pressure gradients tighten on Tuesday as a cut-off mid-latitude low in the Bight approaches, with N’ly winds being dominant. Leftover S swell in the 2-3ft range bottoms out, with NE windswell likely to bump up into the a’noon. We’ll need to come back Friday to see how windspeeds are looking but at this stage NE windswell is likely to build into the 2ft range Tuesday, bumping up further into Wed as the fetch intensifies.
That pattern remains quite slow moving into the end of next week, with both models maintaining N’ly winds through to the end of next week. GFS has a much stronger fetch than EC, so we’ll avoid getting too frothed up over a NE windswell.
Longer term and that slow moving high is still on this side of New Zealand at the end of next week, suggesting small NE windswell for Southern and Central NSW. Tradewinds develop in the Central Coral Sea and there is a possibility of a juicier fetch developing in the South Pacific north of New Zealand later next week, favouring NENSW and SEQLD at this stage. The long lead time suggests plenty of revision in the mean-time.
Check back Fri for the latest analysis.