Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Fri Oct 15 )

Forecast Summary (tl;dr)

• Small, mixed bag Sat, tending to babyfood during the day with all-day offshore winds
• Strong S swell pulse Sun with offshore winds in the AM, biggest PM as winds turn onshore
• Reinforcing S pulse Mon with winds tending N'ly
• Window of clean conditions Tues AM, before winds tend SE and freshen
• Building short range SSE to SE swell Wed, peaking Thurs, easing Fri
• Stronger ESE groundswell potential for next Sun, stay tuned for revisions

Recap

NE windswell picked up through Thursday as the pressure gradient tightened between a high in the Tasman and an approaching complex low and front. That saw surf pick up into the 3-4ft range yesterday, under strong N’ly winds, although there were periods of slack winds in between thunderstorm cells.

This morning has cleaned up as winds swing more NW to W with plenty of good quality, punchy 3-4ft NE swell on offer. A great way to end the working week after a few ugly onshore days. This swell source is now easing  as we head into the weekend.

This weekend (Oct 16-17)

The weekend now gets an upgrade Sunday, as far as size goes, with winds still looking a bit icky in the a’noon. Details below.

Not much change for Saturday. Synoptic W’ly winds generated by the cut-off low will keep surface conditions groomed and we’ll be on the downslope of the NE swell, with some 2-3ft leftovers early, dropping right back during the day. Some small amounts of S swell generated by a front passing well to the south should be worth a few 2-3ft sets on the Hunter and other select S swell magnets, with not much elsewhere. 

Sunday now looks more energetic. A compact but powerful fetch tracks NNE from below Tasmania into the Tasman sea during Sat, as the parent low tracks East of Tasmania. The extra windspeeds in the fetch and favourable NNE track are expected to produce a chunky pulse of S swell, building through the morning and peaking in the a’noon. This is likely to see 2-3ft surf build through the morning into lunch-time, bigger 3ft on the Hunter, before more powerful, longer period surf builds into the 4-5ft range at S facing beaches, bigger 6ft+ on the Hunter. Winds will be best early with W’lies, tending SW as the low moves away then light/mod E/SE as a weak high pressure ridge builds along the coast. Favourable window for those who can time the swell pulse before the wind hampers surface conditions.

Next week (Oct 18) and beyond

Very dynamic, unstable week ahead that has a very La Nina looking signature to it. Primarily the strong, southwards located high and a very troughy pattern in the Tasman sea, that has good swell potential for the region. 

Compared to Wed’s notes the arrival of the high has been slowed by a day. That leaves Mon under the influence of a light NW to N’ly flow, tending to NE seabreezes in the a’noon. 

Leftover S swell from Sunday and the passage of the low across the Tasman should see plenty of fun waves at S exposed beaches, with some 4-5ft sets on the Hunter, 3-4ft at S exposed beaches elsewhere, easing back during the day. Early bird gets the worm with size and conditions.

Tuesday sees the pattern change, with the dominant high moving into position SE of Tasmania and a trough forming along the leading edge of the change as it pushes up the coast. That sees a vigorous S’ly change, with winds turning SE as the trough deepens offshore and directs winds straight onshore. 

All these troughy changes carry the chance of winds tending flukey/offshore around the trough line so it’s worth keeping a weather eye on it if the trough stalls somewhere. Not much swell is expected anyway, leftover 2ft surf, so it’s a marginal call.

By the a’noon, as the onshore pattern winds up, an increasing short range, SE windswell is expected to pick up.

Short period SSE/SE winds swell with onshore S to SE winds is on the cards for Wed as well, so keep expectations low. A fetch of 20/30 knot winds in the Central Tasman is well aimed at Central NSW but with onshore winds we are looking at sloppy, short period 3-4ft surf. 

The second half of next week looks interesting. The block pattern of a slow moving high and trough of low pressure in the Central Tasman remains in place, with an additional large area of low pressure expected to drift down from the South Pacific corridor between New Caledonia and the North Island. 

That spells increasing coverage of the Central and Northern Tasman Sea with E to ESE winds, generating a broad scale ESE swell for most of NSW.

We’ll need to finesse the second half of next week when we come back Monday but we should start to see a more E’ly dominated swell regime through Thursday with local winds easing a notch as the high pressure ridge along the coast weakens. That should see plenty of 3-4ft surf of better quality through Thursday.

The end of the working week looks to dip down, as surf from the local fetch in the Central Tasman dissipates. Lighter winds may tend to morning land breezes which will be welcome, and surf in the 3ft range is expected. 

By next weekend things get potentially very juicy. Low pressure drifting down from the South Pacific corridor is expected to intensify with E’ly to ESE’ly gales aimed back at the East Coast. 

Sat looks undersized due to the timing of that swell, although we can have a fresh look on Mon.

Sunday looks the goods with potential for solid groundswell from the E/ESE building into the 4-6ft range and holding through Mon, before easing.

Winds are tricky but look to be N’ly dominant as the high slips away to the East. 

Longer term and the unstable pattern continues so expect plenty of revision as we deal with model uncertainty which is reflecting a highly dynamic ocean/atmosphere dynamic.

Check back Mon for a full update and have a great weekend.