Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Wed 30th Mar)

Forecast Summary (tl;dr)

• Increasing S to SE winds Wed, with kick in E/NE swell through the PM
• E/NE swell hangs in Thurs AM, as S'ly winds start to increase
• Late increase in S/SE swell likely Thurs as strong front and surface low combine in Tasman, with gale force S'lies developing
• Large S swell Fri/Sat as storm force low sits off coast. Huge seas and gale force S'lies confine surf to only a few spots Fri, winds tending more SW Sat
• Easing through still solid surf Sun, with offshore winds, tending to seabreezes in the a'noon
• Small and clean Mon, even smaller Tues
• Possible S swell Wed, with S'ly winds likely
• Checking the tropics later next week for depression or cyclone, stay tuned for updates

Recap

Surf was around 3ft yesterday with some ups and downs during the day. Winds were fluky around a trough line and with a S’ly bias, better suited to more protected, N’ly facing coastal alignments. Today is seeing a general building trend out of the E/NE, with surf in the 3ft range early, now building to 3-4ft and larger 4ft+ by close of play. Winds are tending S’ly and expected to freshen through the day as a cold front pushes through and a complex trough system with a hybrid, sub-tropical low off NENSW begin to interact. We’re still on track for a very wild XL surf event with a deep low expected to form through tomorrow and become storm force on Fri. Details below.

Building from the E/NE as S'ly winds start to freshen

This week (Mar 30-Apr1)

The complex brew of La Niña mediated weather is as follows: a hybrid sub-tropical low located just off the coast of Ballina is moving slowly northwards while a cold front pushes into the Tasman Sea, extending along the southern coast of NSW. A trough of low pressure associated with the current sub-tropical low deepens rapidly through tomorrow in response to the influx of cold air, forming a storm force low pressure system off the NSW Central Coast overnight Thursday into Friday.

This low is expected to deepen but the main factor is the pressure gradient squeeze between the low (expected to be around 990hPa on Fri) and a very large high (1038hPa) moving well south of the Bight. Storm force winds are proximate to the NSW Coast and are well placed to generate huge seas and XL surf through Fri and into the weekend.

In the short term and E/NE swell generated by a broad fetch of winds feeding into the North Coast low will hold 4ft of surf across most of the region. That gives a clean window at sheltered N facing spots as S’ly winds ramp up through the day. Best to get in early before winds reach their expected strong wind to gale force level. Through the day we’ll see S swell ramp up as the low begins to form in the trough line off Sydney. Thats likely to see surf in the 4-5ft range early, ramp up, especially through the a’noon, where wave heights will climb rapidly into the 8ft range at S exposed breaks. Needless to say, experienced operators only once that swell starts to kick by mid-morning/lunch-time.

No change to the Fri f/cast. Huge and with strong to gale force S’ly winds, that may tend SSW across areas north of Sydney Harbour. A severe gale force low is expected to be about 500km almost due East of Sydney. Winds wrapping around the south-east quadrant of the low are well aimed at Central NSW, as well as areas to the south and north. Expect surf in the 8-10ft range, bigger 12ft+ at more exposed S facing stretches of coastline by Fri a'noon. Only the most sheltered or well known big wave spots will be surfable, as well as a handful of novelty spots. Observing the maelstrom from a distance or hunkering down will be the go for most people.

This weekend (Apr 2-3)

OK, compared to Mondays notes the deep low is now expected to drift slowly S through SSW on the weekend as it weakens. 

That changes the local wind regime as a more SW outflow begins to impact the coast, particularly north of the Harbour and up to the Hunter. 

Size will still be massive Sat. Swell direction should tend a notch more S/SE as the winds on the more southern flank of the low generate longer period swell trains. The big question mark will be winds. If the low tracks S under EC modelling, we’ll see SW winds develop early, opening up a window of potential big wave excellence at certain reefs and big wave spots. We’ll still expect 10-12ft of surf, easing a notch during the day and then further overnight.

Sunday now looks to open up a wider range of surf spots. Winds are much more likely to tend W to SW early, as the low drifts south. A light NW to N flow is probable in the a’noon. With early sets still in the 6-8ft range there should be some really good medium/big surf on offer across reefs and Points. This will ease through the day, down into the 4-5ft range in the a’noon, opening up more recreational-sized surf through the region.

Next week (Apr4 onwards)

With the remnants of the low expected to be drifting off the Gippsland Coast late in the weekend, early on Mon we should see a couple of small days with light winds to start next week.

Residual S-S/SE swell from the low should hold surf in the 3ft range at S exposed breaks on Mon, with light offshore winds extending through the morning.

Surf declines further into Tues with only small 2ft surf from the S and light winds. 

A couple of nice days to check out the coast for new sand formations after the weekend’s swell bombardment.

By Wed a new cold front is expected to sweep up along the NSW Coast. EC suggests a stronger system than GFS, so pencil in a day of S winds and short range E swell in the 3-4ft range. We’ll finesse the size further once we get closer to the event.

High pressure then moves E of Tasmania later next week, with small surf likely to round off next week.

Longer term and as we mentioned on Mon, we’ll be looking to the North as a potential depression or cyclone tracks down through the Coral Sea. This event is starting to shape up. Although GFS has a much better outlook with the system well inside New Caledonia and a supporting ridge generating a broad fetch of E’ly winds through the Southern Coral Sea into the Northern Tasman. That offers up good potential for a slow building E swell possibly next weekend.

EC has more limited surf potential with the system tracking SE more quickly, obliquely to the swell window. There’s still good potential for a SE fetch through the Northern Tasman though, so odds are good we’ll see an increasing surf next weekend. 

Check back Fri for a latest update before the weekend.