Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Mon Sep 23rd)

Features of the Forecast (tl;dr)

• Long period S swell fills in Tues with early offshore winds tending NE in the a’noon
• Mix of easing S groundswell and NE windswell Wed with fresh N’lies tending NW-W later a’noon
• Window of light winds Thurs before front/trough brings fresh/strong S-S/SE winds
• Mix of small S and NE swells Thurs AM before a steep increase in S swell in the a’noon
• Windy and sizey from the S-S/SE on Fri
• Low confidence for weekend but plenty of S/SE-SE swell likely Sat, possibly easing Sun with winds moderating
• Potential low or trough in Tasman next week brings E swells, still lots of model divergence so stay tuned for updates on Wed

Recap

Fun sized S swells kept S facing beaches fairly active over the weekend with Sat seeing 2-3ft surf - 3ft+ on the Hunter under light winds. Sunday saw some longer period swell trains offering inconsistent 3 occ. 4ft sets at S facing beaches for the patient. Still some sets from the S hanging in there this morning with the occ. 3 ft wave on offer under premium offshore conditions expected to tend N/NE before ending up NW/SW in the a’noon as a troughy area hovers about the South Coast before moving offshore.

Nice lines and primo conditions over the weekend

This week (Sep 23-27)

We’ve got a really dynamic outlook this week as a strong high drifts across from the Bight and a trough drawing in tropical moisture from the Indian Ocean moves across the country and eventually enters the Tasman Sea, with a long angled trough and possible surface low expected to form in the Tasman late this week. Run to run and between model consistently is still poor but odds are firming on a large S-SE swell event late this week, possibly extending into next week if the surface low persists in the Tasman. Currently we have some strong frontal activity passing under Tasmania. Read on for details.

In the short run we’ll see offshore winds tomorrow morning as a small, troughy area off the South Coast lingers then moves north, bringing a’noon NE breezes which freshen to mod paces as high pressure moves into the Tasman. Long period swell trains will be propagating up the coast from o/night Mon with super long period swells (20-22 seconds) followed by the bulk of the energy in the 16 second band. This won’t be showing everywhere but some solid sets at S facing beaches and reefs should see some 4ft sets with outliers possible at deepwater adjacent reefs, especially through the a’noon. 

Freshening N-NE winds on Wed as the high moves NE and a trough and front approach from the west. Expect long period S swell sets to 4ft, with an easing trend and some developing NE windswell to 2ft in the a’noon. We should see a window of NW tending W’ly winds between 3pm and dark as the trough and front influence local synoptic winds. 

All hell breaks loose on Thurs as a strong front passes into the Tasman and a trough deepens off the Hunter to Mid North Coast (see below), backed by the strong high in the Bight. Early light winds should be freshening from dawn from the S, reaching fresh/strong wind strength by mid-morning/lunch-time and tending S/SE in the a’noon. Apart from that brief window for the early (favouring the Hunter), we’ll see short range S swells start to rise rapidly in the a’noon with longer period S swells underneath it. By a’noon even sheltered spots will be heavily wind affected with swells building to 6ft+ across open stretches.

Big, wild and windy for Fri. We’ll see revisions through the week but the basic gist of a deep trough and possible surface low moving into the Northern Tasman, likely off the Mid to North Coast appears highly likely. A morning peak in size across the f/cast region to 6-8ft is on track (we’ll adjust up or down on Wed) with fresh S-S/SE winds starting to moderate in the a’noon. Again, you’ll need plenty of wind protection with most spots completely blown out.

This weekend (Sep28-29)

Models are offering divergent outcomes for the weekend with EC suggesting the trough forms a surface low off the North Coast which remains slow moving into the weekend. That will maintain plenty of E/SE-E swell over the weekend with SE winds, easing through Sun. 

GFS model has a broader trough moving NE more rapidly stalling in the Northern Tasman laster in the weekend. That resolution would see easing swells into Sat, in the 4-6ft range with winds tending light/variable.

Smaller leftovers form the SE-E/SE on Sun to 2 occ. 3ft with light winds tending N’ly.

We’ll see how model runs look over the next 24-36 hrs and update Wed.

Next week (Sep30 onwards)

Low confidence in the outlook next week due to low model skill in resolving the trough or low in the Tasman next week. EC has the trough lingering  in the Tasman with a broad infeed suggesting plenty of E’ly swell through the first half of next week with possible offshore winds from the return flow around the trough.

GFS has a less bullish outlook with a weaker surface low drifting towards New Zealand and a smaller amount of E’ly swell.

Either way we should see some quality waves next week from the E’ly angled swell.

Check back Wed for the latest updates.

Seeya then.