Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Wed Sep15)

Forecast Summary (tl;dr)

• Mod SSE swell Thurs hampered by persistent S winds, possibly a window of lighter SW winds early AM
• Better quality SE/ESE swell Fri, reinforcing pulse PM, with lighter winds
• Fun ESE swell Sat AM with good winds, winds tending NE and freshening PM
• More S swell Tues, possibly sizey on Wed. Check back for revision Fri

Recap

Southerly winds have generally hampered conditions over the last couple of days, with junky short period S windswell the dominant swell train. Size has bumped up a notch today as a Tasman low and associated cradling fetch starts to build wave heights across the region. Surf was a choppy 3-4ft across exposed breaks, with some smaller and surfable 2ft surf in more sheltered areas. Nothing great, but enough to get wet and find a fun wave if you weren’t too fussy.

This week (Sep 15-17)

This week's Tasman low formed yesterday, roughly due east of Coffs Harbour and is now in the process of drifting ESE towards the North Island. The latest ASCAT (satellite windspeed) passes show a healthy looking system, though with only a tight core of severe gales aimed up the Tasman Pipe towards South Pacific targets. The broad supporting fetch of SSE/SE winds is better aimed at the East Coast but not especially strong and the system is quite mobile, drifting away through today and briefly flaring up tomorrow as it moves over New Zealand overnight Thursday. A residual trailing fetch out of Cook Strait and adjacent to the North Island through Fri is now weaker than Mondays f/cast notes but will provide a small tail end to the swell. 

High pressure drifting east of Tasmania through tomorrow sees pressure gradients weaken during the day but a S’ly flow is still on the cards. A diurnal SW or SSW flow is likely, especially north of the Harbour, but S’ly winds are likely to kick up a notch at some point before tending SE and laying down through the day. 

Surf wise, size is expected to peak in the 3-4ft range, bigger 3-5ft at exposed coasts like the Hunter, with quality slowly increasing as the shorter period swell trains drop out of the mix. This pulse is then expected to back down a notch during the day, but with winds easing it’s likely to open up some more exposed breaks, if you don’t mind a bit of surface bump and lump.

Friday looks a better for the first proper clean day of the working week. With high pressure drifting north-east adjacent to the central NSW coast a longer period of light offshore breezes should extend into the mid-late morning before winds tend N to NE and freshen through the a’noon. Unfortunately size will be a little on the small side after all that wind we endured. Open exposed beaches will be in the 3ft range, likely bigger 4ft on the Hunter, before a longer period SE/ESE pulse fills in later in the day. This will come with plenty of N’ly wind so you’ll need to find a S facing beach or sheltering headland to hide behind as wind speeds from the a’noon N’ly approach 20 knots.

This weekend (Sep 18-19)

Not much change to the weekend f/cast. Sat AM looks the best of it, with a kick in ESE swell late Fri holding into Sat morning and waves in the 3ft+ range, possibly some 4ft sets at exposed magnets. Light NW to N winds early before winds freshen during the day. These winds should tend NW and even WNW later in the day as a front sweeps in from the west. This opens up a PM session though with size easing from the morning, back into the 2-3ft range.

Sunday's f/cast will still need a little finessing in Friday's notes depending on the strength of the trailing fetch out of Cook Strait later Fri. At this stage, keep expectations pegged, but some 2-3ft surf is likely, and with fresh offshore winds on offer as the first in a series of fronts sweeps across the state it’ll be worth pursuing. Small amounts of NE windswell could be in the mix as well, depending on the strength of N’lies proximate to the coast on Saturday. Surf could get a slight upgrade on Fri if the Cook Strait fetch over-achieves. Winds will tend W to NW through the day, with a late, light Seabreeze possible. 

Next week (Sep 20) and beyond

Plenty of approaching action from the Southern Ocean next week as a series of polar lows approach and pass through the Tasman, with associated cold fronts. Still some model divergence on the fate of these fronts as they approach the Tasman, so revision is likely on Friday.

W’ly winds are likely to iron out surf to tiny/flat on Mon so we can dial that in.

Gales out of Bass Strait Mon, despite being very zonal (W to E) and aimed at New Zealand targets are likely to see a small amount of refracted S swell Tuesday morning, with W’ly winds tending more WSW to SW through the day as a more serious cold front fetch pushes NE into the Tasman late in the day. This is likely to see a steep increase in S swell later Tuesday, possibly up into the 5-6ft range at S facing beaches.

GFS has a much stronger fetch- basically covering the entire Central Tasman with SW gales- than EC, bringing a substantial S swell into play for Wed with fresh SW winds, easing during the day as the front pushes across the Tasman and pressure gradients ease.

More fronts pass from the middle of next week, more zonal than meridional, suggesting a series smaller S pulses into latter next week and the weekend. This will be subject to revision on Fri so check back then for a full analysis.