Sydney Hunter Illawarra Forecast by Steve Shearer (issued Mon July 28th)

Features of the Forecast (tl;dr)

• Small background E swells persist this week
• Small flush of S swell Tues PM slightly bigger Wed 
• W’ly winds Tues, and into Wed AM with a SW-S flow developing Wed (remaining offshore on the Hunter)
• Sizey short range S-S/SE swell developing Thurs with mod/fresh S’ly winds
• S/SE swell and S-S/SE winds persisting into Fri
• Dynamic weekend with intense low forming off NENSW/SEQLD
• Likely moderate S/SE swells Sat, increasing Sun with S/SE-SE winds (depending where low forms)
• Possible quality E/SE swell developing next week with offshore winds as low drifts towards the North Island

Recap

The weekend came in close to script with Sat seeing workable NE windswell offering mostly 3ft sets with the occ. bigger wave, messy early before cleaning up thruogh the a’noon as N-NE winds shifted more NW. Small and clean on Sun with tiny leftover NE swell and inconsistent E’ly swells offering 2ft sets under bluebird skies. Today is seeing another day of small clean E swells hovering in the 1-2ft range under W'ly winds.

Nice conditions, not much swell

This week (Jul 28-Aug 1)

High pressure is up over sub-tropical NSW, drifting into the Tasman and a massive low which swept up over the SE of the continent is now moving SE of Tasmania without showing too much in the way of swell generating winds for the east coast. A retreating broad trade fetch feeding into a trough is still supplying small E’ly swells. As mentioned on Fri- we’ve got an unstable atmosphere expected over the Tasman this week with an inland surface low pressure modelled to move into the Tasman mid week before moving away swiftly to the east. Over the weekend there’s now growing agreement on a coastal low (possibly some variant of an ECL) to form off the NENSW or SEQLD coast and intensify as it moves into the Tasman, with potential for severe weather and sizey swells. There’ll be plenty of revisions as we move closer to this event so we’ll outline it today and tighten the focus as we move through the week.

In the short run troughs related to the current decaying low SE of Tasmania generate bands of W-SW winds across NSW and adjacent to  Tasmania. That will see a mostly W’ly flow across the temperate region tomorrow, with potential for winds to shift NW to N in the a’noon as another trough arm related to the next inland low approaches the region. Not much surf around- just a continuation of small, background E swell to 1-2ft and some minor S swell to similar sizes. 

Wed sets a little more S swell generated by the SW-S fetch adjacent to Tasmania. Windspeeds are weak, so we’re only expecting size in the 2ft range initially, building through the a’noon to 2-3ft (bigger sets on the Hunter and other S magnets). A small boost in E’ly energy looks likely - adding inconsistent 2ft sets to the mix. Winds look tricky as the inland low and trough exit the coast between Sydney and the Hunter coast. Light/variable winds early will have a W’ly component so conditions looks clean at least for the early session. As the trough/low exit the coast we’ll see SW-S winds freshen on the southern side of the low axis, W’ly winds north of the low. Best guess at this stage would see offshore winds all day across the Hunter, with the SW-S flow across the Illawarra to Sydney region. 

The low winds up o/night Wed into Thurs with a broad flank of strong S/SE-SE breezes developing on the southern flank. That will generate a fairly sizey but short period S/SE swell through Thurs under mod/fresh S’ly winds. We should see size up in the 4-5ft range at exposed breaks but of low quality, cleaner and smaller into the more sheltered breaks. 

A strong high pushing through the Bight holds a ridge along the coast Fri so S’ly winds continue at mod paces. We should see a period of W-W/SW breezes inshore early, especially north of the Harbour although open beaches are likely to remain wind affected. Size comes down a notch as the low pressure system moves away quickly with size in the 3-4ft range likely. Again, keep expectations pegged low as far as quality goes but there should be surfable options. 

This weekend (Aug 2-3)

There’s broad model agreement now for a low to form off the sub-tropical coast and merge with a Coral Sea low pressure centre, deepening explosively through Sat and into Sun. Exactly where the low forms and moves will have a large material impact on surf size and especially local winds- so keep that in mind particularly if you are planning to chase the swell. 

Basically the ECMWF resolution is for the low to form off the North Coast closer to Coffs with offshore winds across most of the North Coast and SEQLD through Sat, strong onshore SE winds across the MNC and extending southwards through the Hunter and Sydney-Illawarra, although with decreasing speed as you head south. 

GFS has the low forming off the SEQLD coast with onshore winds across the Gold Coast and North Coast, extending down to the Hunter and Sydney at much lighter strength and tending more S’ly. 

Both models suggest a rapid deepening into Sun with gales to severe E’ly gales developing in a broad fetch across the Southern flank of the low. 

Either way we are looking at a significant weather and surf event- likely focussing on the MNC for maximum size at this stage over the weekend with onshore south of the low impacting most of the coast down to Ulladulla. 

Ballpark for size is likely to be in the 3-5ft range Sat, bigger 4-6ft Sun (much bigger north of Seal Rocks)- but those figures are likely to be revised as we get more clarity on how the situation will evolve.

We’ll dial in details further on Wed.

Next week (Aug 4 onwards)

As the deep low moves eastwards towards (and possibly over) the North Island it aims up gales to severe gales back towards the east coast (see below) and we’re on track to receive some powerful swell from the SE-E/SE through next week. 

Sizey into Mon in the 4-5ft range but we’ll be waiting for the stronger longer period swell to fill in later Tues and into Wed.

That looks to offer some real size and quality in the 6 occ. 8ft range.

High pressure should be drifting over NSW during this time suggesting light offshores and light a’noon seabreezes. 

Still a lot of water to go under the bridge before we get there - so expect revisions when we come back Wed- hopefully not downwards. 

Seeya then.