Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Wed Oct 20 )

Forecast Summary (tl;dr)

• S swell easing Thurs as fun swell from the ESE swell builds in and SE'ly winds begin to ease in the PM
• Fun-sized ESE/E swell Fri with good winds AM
• Mix of E and ENE swell Sat with window of good winds AM
• Stronger ENE swell Sun, with fresh S'ly winds developing and S'ly windswell building
• ENE swell peaks Mon, easing back Tues combined with S'ly swell and easing winds
• Strong S'ly swell Tues and Wed with potential good winds Tues AM
• Easing S swells Thurs/Fri next week

Recap

South swell trains have maintained fun sized surf across the region since Monday. Yesterday saw leftover longer period S swell in the 3-4ft range at S facing beaches. Conditions were clean early before a S’ly change reached the Sydney basin around midday. That change ran out of steam quickly and with weaker pressure gradients than expected light offshore winds were able to establish through the night, producing another morning of clean waves in the 3ft range before SE winds hacked into it . The troughy pattern continues through the end of the week. Details below.

This week (Oct 20-22)

Yesterday’s troughy S’ly change has now spawned a small, weak, surface low, which ASCAT (satellite windspeed) passes show to be offshore from Jervis Bay. This small low, is cradled by a large (1033hPa) high located in a very southerly latitude SE of Tasmania. The interplay between the two systems is producing a fetch of E/SE winds through the Central Tasman, in effect a sub-tropical looking tradewind style fetch we might see in Summer. Another weak, troughy low centre is located off the Mid-North Coast.Windspeeds are expected to remain on the low side, less than 30 knots, so we’re not looking at anything on the large side, but the more favourable swell direction should see a more even spread of wave heights compared to the more directional S swells we’ve been getting.

A tighter fetch of S’ly winds adjacent to the Central NSW coast through today is expected to generate short period S swell through tomorrow morning, in the 3ft range at S facing beaches, smaller elsewhere. Swell trains from the SSE/SE are expected to fill in through the day, maintaining size in the 3ft range. Winds look a bit stinky for the morning session, with mod E’lies but they are expected to lay down in the a’noon as local pressure gradients ease. 

Friday looks the much better bet. ESE swell from the small Tasman low is expected to peak through the day, building from the 3ft range into the 3-4ft size class. A weak, troughy airmass and weak high pressure cell off sub-tropical NSW should see light and variable breezes for most of the day, before NE seabreezes kick up through the a’noon. Lots of fun, peaky options to end the working week. 

This weekend (Oct 23-24)

Not much change to the weekend f/cast. Winds will make things tricky for Sunday as a strong S’ly establishes.

Saturday sees easing ESE swell from the weak low in the central Tasman. The morning looks the best of it, with leftover 2-3ft surf, easing back during the a’noon. Light morning NW to N winds.

Sunday is a dynamic day. A strong front and advancing trough is likely to push through overnight Sat, with S’ly wind established by first light Sun morning. The close range S’ly fetch is likely to whip up a short range S’ly swell during the day, into the 3-4ft range at exposed S facing stretches on the Hunter, 3ft elsewhere. 

E’ly swell trains from a more distant source make landfall on Sunday. These swell trains are generated as a deep, angled trough through the area between the North Island and New Caledonia merges with the remnants of the Tasman low and focusses E to ENE winds in a broad area near the North Island during Friday. Expect a significant signal from the E/NE to develop during the day, likely building from 3ft into the 3-4ft range, possibly with some 5ft sets at E swell magnets. This will obviously favour spots with protection from fresh S’ly quarter winds.

Next week (Oct 25) and beyond

Lots of potential next week as our very active Spring continues. The front producing the weekend S’ly change spawns a low East of Tasmania, which is expected to be slow moving through next week, possibly even retrograding back into the Tasman and providing multiple pulses of S’ly swell through next week. 

E/NE swell from the North Island source is expected to peak through Mon. Mid period punchy energy should see size in the 4-5ft range through there morning at favourable E swell exposures, easing during the day. S swell trains will be in the water too, with 3ft of raggedy energy bulking up in power during the day as the period lengthens. With S’ly winds easing during the day and tending to light E’ly breezes there should be plenty of options on offer. 

Tuesday offers plenty more surf potential with another combo swell day on the cards. Easing E swell and strengthening S swell is the gist of it.Light offshore winds early suggest fantastic beach break potential with leftover 3ft E swell easing and 3-4ft of S swell expected at S facing beaches, likely 4ft on the Hunter. 

Slightly longer period S/SSE swell generated by a northwards moving fetch from the low east of Tasmania during Mon is expected to provide the peak of the S swell on Wed next week. Size is likely in the 3-5ft range at S facing beaches, bigger 4-6ft on the Hunter coastline. Winds will still be fresh from the S’ly quarter so protection will be needed, shaving off a lot of the size.

Into the end of next week and easing is expected, as swell from the S generated by the Tasman low, eases back through Thursday and moreso on Fri. Models are divergent on the outcome towards the end of next week, with GFS sliding the low slowly towards the North Island where a decaying fetch out of Cook Strait may provide a small pulse of ESE swell into next weekend (30/31 Oct). EC suggests a high in the Northern Tasman, with NE winds, potentially strong enough for small NE windswell.

No doubt with the long lead time, those scenarios will be revised.

Check back Fri for a fresh update for the weekend and next week.