Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Fri 25th Mar)

Forecast Summary (tl;dr)

• Strong onshore winds Sat with a slight increase in short range E swell and some long period S swell in the PM
• Short range E swell persists Sun with tricky wind outlook- mostly onshore though lighter winds possible around trough line
• Long period S swell pulse Sun/Mon
• Uncertainty persists for Tues/Wed with small surface low off Sydney- likely small mix of E/NE and SE swells
• Major increase in S/SE swell likely Thurs as strong front and surface low combine in Tasman
• Solid blend of S and S/SE swell likely Fri, slowly easing next weekend with S/SE to SE winds

Recap

Yesterday was mostly a write off with end to end onshore winds and surf in the 2-3ft range, a notch bigger on the Hunter. Scrappy surf for the very keen only. Today has seen a very big improvement in surface conditions with a light and variable flow early and mostly clean surf ranging from 2ft at most places with some bigger 3ft+ surf on the Hunter. A lingering trough and area of light pressure gradients is maintaning favourable winds across most of the region into the lunch-time zone, with SE winds expected to set in through the a’noon. All in all, a few small, clean options to end the week. 

Clean-ish, workable options to end the week

This weekend (Mar 26-27)

Bit of flip flopping required on the weekend f/cast. Mondays f/cast was small, Wed got an upgrade, Today gets a downgrade back to Mondays call. The reason is the trough which was expected to drift south from the North Coast and aim up a proximate fetch of E’ly winds at the Central NSW Coast is now expected to stay much more northwards in latitude. 

That means the strength of the E’ly winds in the swell window is much reduced compared to Wed’s notes. No great change to the onshore flow which will see SE winds in the 15-20 knot range tending E’ly through the day at similar strengths. Any window of lighter winds will be brief and early. 

Size will be in the 2-3ft range with a dominant short period E’ly swell. Through the a’noon there’ll be some longer period S swell in the mix with 2-3ft sets at S facing beaches but it’ll be mostly wasted in amongst the prevailing onshore sea state.

Sunday will be tricky to work with too, with onshore winds tending more E then E/NE through the a’noon. Short range E to E/NE swell will build a notch in the 3ft range and long period swell trains will see inconsistent 3-4ft sets at S facing beaches but prevailing winds are going to make finding any quality very difficult.

The caveat is areas of lighter (variable) winds are possible around a trough line south of the Illawarra to the South Coast. Check local wind obs before you drive.

Next week (Mar28 onwards)

A coastal trough and an interior trough set up the start of next week. Winds along the trough line will be light and variable early, tending NE through the day. The E’ly infeed tends more E/NE to NE later Sunday, with surf from that direction prevailing on Mon. Size will boost up into the 3-4ft range, along with long period S swell which will peak in the morning with inconsistent 3ft sets, before easing during the day.  The trough may deepen into a large area of more organised low pressure during the a’noon, seeing W winds develop north of Sydney and S to SE’ly winds along the South Coast/Illawarra region. Low confidence on that wind outlook depending on where the low develops. 

Low confidence extends into Tuesday with EC placing the low just offshore from Sydney. A SE flow along the southern flank of the low is expected (from this scenario) from the Illawarra up to Cronulla, with a more variable flow north of the Harbour and a light offshore flow on the Hunter. Expect continuing 2-3ft of E/NE swell under the EC scenario.

GFS places the low further SE of Sydney, out in the Tasman Sea. This sees S/SE winds across the region and developing short range S to S/SE swell through the day along with residual E/NE swell feeding in from the Central Tasman.

This extremely complex, dynamic brew extends from Wed next week. We’ll be revising this substantially on Mon but the basic outline is another surface low developing off the Mid North or North Coast later Wed. This is then augmented by a major front pushing into the Tasman, merging with the surface low to create a large area of low pressure in the Tasman. Under current modelling the resultant S to SE winds would cover the majority off the Northern, Central and Lower Tasman Seas, generating a large S to SE swell, beginning Thursday.

This is likely to build into the 4-6ft range Thurs and become solid 6-8ft during Fri, with fresh S to S/SE winds accompanying the swell. 

This could be a major under call due to GFS powering most wave models and EC suggesting a much stronger system, which would see 8ft+ or larger surf during Fri.

A slow roll off in size is then expected next weekend, first weekend in April as the low moves away.

Looks like the first major Autumn swell from this source is now on the radar. 

We’ll keep tabs on the situation over the weekend and come back Mon with a full update.

Until then, have a great weekend!