Sydney Hunter Illawarra Surf Forecast by Ben Matson (issued Mon 10th Apr)

Forecast Summary (tl;dr)

• V.large renewal of S'ly swell Tues (good morning winds), easing Wed onwards
• Moderate+ S/SE swell persisting Wed thru' Fri
• Good conditions Wed with light winds; developing S/SW winds Thurs lunch onwards
• Fun weekend mix of easing S/SE swells and small E/SE swell
• Large E/NE swells building early next week
• More S'ly swells beyond that

Recap

Easterly swells delivered plenty of fun waves on Saturday in the 2-3ft range, with building southerly swells on Sunday pushing 3-4ft at south facing beaches. A larger south swell increased into the 4-6ft range this morning, pushing 6-8ft across the Hunter though the swell direction has been very steep and not all beaches have seen the same levels of energy. Conditions have been generally clean for much of the last three days under a westerly flow (though southerlies have kicked in this afternoon). 

Newcastle this morning

This week (Apr 11 - 14)

A deep Tasman low positioned midway between the Apple Isle and New Zealand is responsible for the current south swell. And it's not over yet.

A secondary fetch of broader southerly gales are wrapping around its western flank (see below), buffeting the eastern Tasmania coast with large windy swells, and this energy will push across Southern NSW on Tuesday.

In similarity to today, the swell will remain acutely south, which means there'll be a very wide variation in surf size between south swell magnets and sheltered southern ends. However, the sustained nature of the parent system, and the fact that the current fetch is working upon the active sea state generated by the last few days of wind, means that surf size will become even bigger into tomorrow than what we saw today.

How big? Most south facing beaches should push well into the 6-8ft+ mark, it's quite likely that a few of the regional swell magnets and offshore bombies will push much higher into the 10ft+ range. Elsewhere, beaches not open to the south will be smaller though expect things to be a notch or two higher than today.

Conditions will be clean with moderate to fresh W/SW winds. By around lunchtime they'll veer SW (earlier with increasing southerly latitude) and some locations may see a S/SW flow at strength into the afternoon, so aim for the morning for the best conditions.

Although the Tasman low is now weakening, it will remain slow moving for a few days yet and a broad S/SE fetch will develop off the SW tip of NZ's South Island that'll maintain low-end S/SE gales in our swell window until Thursday.

This renewal of energy will arrest the otherwise easing southerly swell trend from Tuesday evening onwards, generating 4-6ft surf from Wednesday through Friday (the upper end of this size range more likely Wed than the other days). 

Even better, conditions are looking clean Wednesday with light W'ly winds, ahead of a developing S'ly tending S/SE flow from lunchtime Thursday into Friday. So, make the most of Wednesday for the best options, but there'll be plenty of surf for the second half of the week too.

This weekend (Apr 15 - 16)

Easing S/SE swells are expected over the weekend but we've got a minor flush of E/SE swell due, sourced from a small fetch of gales exiting western Cook Strait later Thursday and into Friday. 

Initially most of this fetch will be aimed towards the South Coast (and Tasmania's East Coast) but most of the Sydney, Illawarra and Hunter coasts should pick up some decent 2-3ft sets both days. Saturday should kick off with leftover 4ft sets from the S/SE anyway, and conditions will be clean all day Saturday and early Sunday with light varibale winds. 

Sunday afternoon may be spoiled by freshening NE breezes but we'll have more on that in Wednesday's update.

Next week (Apr 17 onwards)

We've got a complex, dynamic long range forecast right now, thanks to a redevelopment of what's essentially the same broadscale troughiness over the Tasman Sea related to our current south swell, and this week's impending S/SE energy.

A slow down in the eastward progression of long wave troughs - a blocking pattern if you will - is likely to allow the surface trough to deepen a number of low pressure centres, that will in turn form a broad E/NE fetch across the NZ region next weekend. This looks to generate a heavy E/NE swell for the Australian East Coast, arriving early next week and peaking Tues/Wed. 

It's too early to have confidence in the likely size range and duration (and focus of the biggest surf), but early indications are for some very large waves, probably into the 6-8ft range, with periods of clean conditions as the regional frontal progression resumes across the SE corner of the continent (also generating some fresh S'ly swells for the second half of that week).

Let's see how the model guidance is stacking up on Wednesday!