Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Wed 19th Apr)

Forecast Summary (tl;dr)

• Mod/large E’ly-ENE’ly swells holding at sizey levels Wed/easing Thurs as trough/block pattern sets up
• Rebuild in E-E/S swell Sat, easing Sun S’ly winds both days, lighter SW inshore early
• Easing surf early next week
• Likely run of E/NE tradewind swell building from mid next week
• Possible trough/surface low next week, low confidence so check back Fri
• Eastern swell window remains active next week

Recap

East swell yesterday came in around forecast expectations with an even spread across the region in the 4ft range. Winds were light offshore early, clocking S’ly and then variable SE-NE from mid a’noon. Today has seen a thickening up as a longer period pulse fills in, albeit fairly slow and affected by a big morning tide. Sets to 4-5ft have been reported with the odd 6ft rogue. Conditions were clean early with W-W/NW winds, tending to light NE breezes during the day. 

Bit slow but plenty of size when they came

This week (Apr19-21)

We still have the trough block pattern in place with the South Pacific low centre contracting away to the NE while a secondary low centre retrogrades back into the Tasman Sea. An anchoring high is being shunted away with a trough and front expected tomorrow before a new dominant high moves in from the Bight.

In the short run and a stiff S’ly change should be in across the region by first light- possibly with a slight W’ly component north of the Harbour and Central Coast before winds tend strong SE during the day. We should see todays pulse hold into tomorrow morning with size in the 4-5ft range (the odd 6ft set) before a slow easing trend sets in. There’ll be some short period SSE swell in the mix as well, not significant at protected spots. Obviously, sheltered spots only with fresh S-SE winds on offer. 

The fresh S/SE flow extends into Fri so you’ll need hit up the sheltered spots again.  We should see a slight moderation in windspeeds through the day - but not enough to clean up the open beaches, they’ll remain wind affected. East swell continues to slowly roll off in size with 4ft sets, easing down to 2-3ft during the day.

This weekend (Apr 22 - 23)

As mentioned in Mondays notes the trough block buds a small retrograding low which tracks SW back into the Tasman Wed/Thurs. We’ll see an E-E/NE infeed fetch into this system and a return SSE fetch on the bottom flank of the low.

Saturday see a rebuild from the E’ly fetch with sets back to 3-4ft and with more consistency due to the closer proximity. Mod S’ly winds should be SW inshore early across most of the region so worth getting up for although it may take a little bit of time for that pulse to fill in properly so give it another look if it looks undersized early.

A slow easing is expected Sun under lighter winds with an offshore flow early and light/mod SE winds through the day. 3ft sets will become slow and and ease back down to 2-3ft during the day. 

Next week (Apr 24 onwards)

The blocking trough pattern breaks down next week as a very strong high moves into the Tasman with a very firm ridge up along the sub-tropical coast ( the so-called Quidge), weaker down in temperate latitudes. 

Mod/fresh SE winds (tending E’ly in the a’noon) are on the menu Mon, with a small amount of residual E swell around 2ft only rideable at protected locations.

By Tuesday the high will be in the centre of the Tasman with a classic blocking signature- SE winds in the sub-tropics, E-NE winds from the Hunter southwards. 

That in itself will see stacks of sizey trade swell develop in the north, with E-E/NE swell filtering down into the temperate regions likely from mid next week. 

Complicating matters we’ve seen a trough develop off the Mid North Coast on recent model runs. If the trough moves offshore we may see a surface low develop with potential for sizey surf and onshore winds later next week.

Failing that, an approaching front should see winds tend NE and freshen later next week and then turn offshore as the front pushes through.

We’ll keep tabs on it but it looks like the eastern swell window will remain active for a while yet.

Check back Fri for the latest.