Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Fri 21st Apr)

Forecast Summary (tl;dr)

• Rebuild in E-E/S swell Sat, holding Sun AM before easing
• Mod S’ly winds both days, lighter SW inshore early
• Slowl easing E'ly groundswell from Monday, minor pulse of short range E/SE swell Mon/Tues but also easing
• Small flukey S'ly swell Mon/Tues, and then another late Wed/Thurs (only favourable south swell magnets)
• Strong E/NE swell next Sun onwards

Recap

Solid combination surf from the E and SE yesterday eased from a peak in the 4-5ft range into the 3-4ft range with mostly terrible surface conditions under a stiff SSE flow. Surface conditions are still being marred by S’ly winds today with surfable options confined to more protected corners with 3 to occasional 4ft of swell is being reported.

This weekend (Apr 22 - 23)

A few minor tweaks to the weekend f/cast with winds just a bit more robust than they looked on Wed.

The S’ly flow looks a notch more entrenched , especially for Sunday as a monster high pressure cell moves in from the Bight.

Sat morning should see the lightest winds with a period of SW winds inshore early before light/mod S’lies kick in and tend SE.

Surfwise, no real change to the f/cast. A rebuild in mid-period E-E/SE swell pushes surf back up into the 3-5ft range Sat, likely strongest mid morning onwards but winds and tide will both be major players in surf quality so compromises are likely. 

Size holds in that range for Sun morning before easing with a window of SW winds tending stronger S-SE through the day. 

Long story short, you’ll find waves this weekend if you can work around the S’lies. 

Next week (Apr 24 onwards) - updated by Ben Matson (as Steve had to jump on to WSL commitments)

The story next week is a very strong high (1033hPa) sitting in the Tasman with a firm ridge extending up the eastern seaboard. This will keep the Southern Ocean storm track at low latitudes, and allow for light winds for a few days before northerlies kick in throughout the second half of the week. 

First up, there's an unusual aberration in the model guidance for Monday afternoon. Through the morning we'll see slowly easing E'ly swells from the weekend with clean conditions under a light variable flow, but the models show a kick late afternoon with the east swell jumping from 1.0m at noon to 1.6m at 6pm (see below). 

This appears to be a case where the model has combined swell trains - easing E'ly swell around the 10 second mark and new E/SE energy around the 7-8 second mark (generated by a building ridge atop the aforementioned Tasman high). You can see this in the data for 12pm Tuesday where the model splits it back into individual swell trains.

Short version is: the graphs are exaggerating wave heights/trends for late Monday.

Here's another piece of complexity - an undercalled long period south swell for Monday. It'll be generated by a powerful low and trailing W/SW fetch below Tasmania this weekend (see below), that's poorly aligned in our southern swell window - however we should see a small spread of directional south swell on Monday. Models have peak periods in the 16 second range but it'll likely be very flukey, bypassing most beaches (still relying on the leftover E'ly swell) but some south swell magnets could pick up 3-4ft sets. I'm looking at you, Hunter. 

The overall swell combo trend looks to slowly decline through the middle to latter half of the week though we'll see small waves every day. Another spread of small, flukey long period S'ly swell is due later Wed/Thurs from a polar frontal passage but it won't light up many beaches away from the reliable south swell magnets. And northerly winds will reduce options to protected northern corners. 

Long term has a broad trough in the Coral Sea/South Pacific later this week that's shaping up to be an excellent E/NE groundswell producer from Sunday thru' the following Wednesday (current peak late Mon/Tues).  Very promising signs for more great waves.

Have an unreal weekend, see you Monday!