Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Mon 4th July)

Forecast Summary (tl;dr)

• Large SE swell Mon with onshore winds for most of the region (possible variable/offshore on the Hunter, depending on trough)
• Easing SE swell Tues AM, with rebuild in large S/SE swell PM and strong S/SE winds
• Plenty of SE winds and swell Wed
• Rebuild in size from the SE-ESE Thurs, holding Fri with a spike of S swell in the mix and fresh SSW winds
• Plenty of size into Sat with uncertain wind outlook
• Strong E/SE groundswell likely this Sun PM, holding Mon with uncertain wind outlook
• Tracking more potential low pressure development next week but low confidence due to model divergence, stay tuned for revisions

Recap

An Easterly trough low formed almost due East of Sydney on Sat (note: BOM refers to it as ECL), with a brief window of clean conditions across Southern Sydney, extending through into the a’noon from the Central Coast and Hunter. Size was in the 3-4ft range from S swell and fun.  Onshore winds smashed conditions for most of the region later in the day. Sunday was a mess with strong to gale force onshore winds and flood rain as the low deepened off the Coast. Size was hard to ascertain in the victory at sea conditions but somewhere in the 8-10ft range. 

This morning has seen the low drift slowly NE, in a weakening phase. Winds swung NW from Newcastle northwards with the rest of the region seeing continuing strong winds which have backed more S/SE. Plenty of unruly size in the 6-10ft range and poor water quality due to flooding and stormwater run-off. 

North of the trough-line= light offshores

South of the trough= howling onshores and rain

This week (July 4-8)

Tasman Sea is looking very, very spicy this week with our current low looking to meander N and E, then S and reintensify later in the week, spraying the East Coast with swell with more favourable conditions. We’ve currently got a strong pressure squeeze between a dominant high in the Bight (1033 hPa) and the complex low system off the Central NSW Coast. Current ASCAT (satellite windspeed) pass shows strong winds to low end gales extending due E of the Central down to South Coasts. A long trough-line extends down from the Northern Coral Sea into the Tasman- a continuing  source of instability. The interplay between the low and the strong high will see stormy conditions and strong S’ly quarter winds extend for most of this week with a clear moderating trend by Friday.

In the short run and strong S to SE winds hold through Tues and Wed as the current synoptic pattern continues. The SE fetch extends further into Tasman through the day and that is likely to generate increasing swell from the SE. Size won’t drop much into Tues, but by close of play will rebuild back into the 8ft range.

That size holds into Wed morning. At least a solid 8ft, with tons of wind on it. Protected spots only and even they are likely to be wind affected Wed. Looks like another lay day.

By Thurs some options may open up for the hardy. A reintensification is likely due E of the region Wed (see below), as a complex low pressure area in the Tasman interacts with the trough line extending southwards from the Coral Sea. That’s likely to both see an increase in E/SE-SE swell- not that it will have dropped much, but surf should rebuild back into the 8ft range Thurs. Winds look to swing more SSW, possibly even SW through the day. That may clean up some the more protected spots in the region. Especially some of the big wave reefs.

Complicating an already stacked chart is a cold front pushing through Fri. That is likely to see stiff SSW winds through the morning, easing back in the a’noon and tending SW. Expect a combination of steep rising short-range, directional S swell and E/SE swell in the 6ft range Fri.  With winds expected to ease back in the a’noon, sheltered and semi-sheltered spots should clean up, although there’ll still be some residual lump and bump from such an agitated sea state.

This weekend (July 9-10)

Still a significant amount of model variation surrounding this weekend, which makes these calls subject to low confidence, and likely to be revised come Wed. Especially the wind outlooks.

Surf-wise we’re still up for plenty of size, with the low drifting towards the West Coast of the South Island, likely reinvigorating later this week. That should see at least 4-5ft of S-SSE swell. Winds will be dependent on the low position and how Fridays front evolves. Latest GFS suggest still plenty of SSW to S winds Sat.

EC has a weaker area low pressure in the trough line East of the region, with lighter SW to W winds through Sat.

With such a dynamic pattern we’re going to have to revise Wed. Some kind of S’ly quarter wind is highly likely.

Sunday looks a similarly shaky bet. Gales forming off the SW of the South Island through Fri into Sat (see below) should see a strong pulse of SSE groundswell Sun so swell with not be a problem. We’ll finesse size and timing Wed but we should see at least 4-6ft of size through the a’noon.

Winds will be dependent on another troughy area of low pressure off the Coast. EC suggests the area lingering off the Hunter, with light SW breezes.

GFS has a stronger high pressure ridge setting up with mod/fresh SE winds developing Sun. 

Don’t block anything out, but keep the pencil handy to get a surf in Sunday if the wind f/cast swings our way.

Next week (July 11 onwards)

Dynamic, troughy outlook is playing havoc with weather models, so we look into next week with extremely low confidence.

Some sort of low pressure development in the Tasman looks almost certain next week. 

The fetch near the South Island maintains strong surf from the SSE-SE into Mon, with the addition of more E’ly angled swell from a Cook Strait fetch over the weekend. Winds are still up in the air.

EC suggests then another complex low in the Northern Tasman, rapidly developing E’ly gales aimed at a wide swathe of the East Coast and solid E’ly swell incoming later Tues into Wed/Thurs.

GFS has a much more modest SE flow adjacent to the sub-tropics with a troughy pattern developing over Central NSW. That will see surf diminishing from Tues into next week.

To be honest, I think the models are struggling to resolve the pattern and a “watch and wait” attitude is the most appropriate one. 

EC sure looks juicy though!

Check back Wed and we’ll see how it’s shaping up.