Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Wed Mar 13th)

Features of the Forecast (tl;dr)

• Strong E/NE trade swell peaking Wed, easing Thurs, with generally light winds and NE sea breezes
• Small south swell building Wed PM, showing best Thurs
• Fri a write off with poor winds and raw windy S swells
• Nice south swell building Sat (may be wind affected tho), showing best Sun with favourable light winds
• S swells persist into Mon with light morning winds
• Short range E/NE swells Tues, easing Wed
• Possible sizey/windy S-SE swell Thurs/Fri next week if trough deepens in Tasman Sea
• Potential S/SE groundswell Thurs/Fri next week
• Likely building/workable E/NE swells from tropics late next week into next weekend
• Local winds looking tricky later next week- check back Fri for latest updates

Recap

E/NE swells from an incredibly broad and strong tradewind fetch have reached temperate NSW with yesterday seeing surf in the 3-4ft range under light winds tending N’ly. We’ve seen surf build further into today with stronger 4ft sets under light morning winds (mostly offshore) with a light/mod NE seabreeze expected to set in after lunch. Some S’ly groundswell is expected to show at S swell magnets in the a’noon so keep eyes out for that. 

Set gets the pack scrambling

This week (Mar 13 - 15)

We’ve still got a broad trade wind flow in the Coral Sea, extending out into the South Pacific and anchored head and tail by low pressure along the monsoon trough. That’s producing heavy swells in the sub-tropics (full blown Point surf equivalent to cyclone swells) with a fair amount filtering down to temperate NSW. 

In the short run we’ll see size hold at current levels 4ft (occ bigger) sets and some small S swell leftover from today. Winds look good for tomorrow morning with an advancing trough seeing a morning NW tending even more W/NW flow lasting until lunch-time. The trough brings a gusty S-S/SE change in the early/mid a’noon so get in before that.

Strong S’ly tending SE winds Fri as a new high pressure ridge builds in behind the change, with pressure gradients tightened from the trough on the leading edge of the change. There’ll be some sloppy, raw surf around for the very keen (short range S-SE swell to 3-4ft and some frontal derived S swell late in the day) but for most it’ll be a lay day due to the strength of the SE flow.

This weekend (Mar 16 - 17)

Winds still look unruly for Sat with the high moving into the Tasman and the SE flow shifting more E/SE then E’ly through the day. That will be the main determining factor for surf quality although as Ben noted on Mon winds will be lighter south of Jervis Bay and we will see overall windspeeds decrease through the a’noon as pressure gradient slacken. Best to expect some lump and bump around though with a mix of swell trains in the water. We’ll see some short range SE swells and better quality S from the frontal passage across the Tasman, all adding up to 3-4ft at S exposed breaks.

Sunday looks a better bet for S facing beaches as winds shift to the NE. These S facing beaches look to be pretty solid Sun with a mix of swell trains on offer. Ben mentioned an ice shelf fetch from a slow moving low later this weekend, there’s also a current ice shelf fetch set-up with ASCAT passes showing strong gale to storm force winds aimed back into the Tasman Sea. That will add energy to frontal S swells with 3-4ft surf likely to show bigger 4-5ft sets in the a’noon and some S facing reefs offering up even bigger sets. Light N-NW winds early shifting NE look the goods for S facing beaches.

Next week (Mar 18 onwards)

Sundays mix of sizey S swells persists into Mon with 4-5ft surf at S facing beaches under light morning winds tending NE and freshening in the a’noon. We should see some short range E/NE swell from the top of the high (see below) start to fill in across this signal through the a’noon.

This initial burst in E/NE swell from a more local source looks to persist into Tues at moderate levels (3ft or so) before the fetch migrates E’wards and rebuilds in the South Pacific slot between the North Island and New Caledonia. That should see an easing in E/NE swell mid week and a potential rebuild in size late in the week and into next weekend.

So Wed looks like the low point in swell energy for next week although we’ll still see 2-3ft surf from the E/NE with uncertain winds.

The uncertainty rests on a potential trough moving into the f/cast region.

GFS has the trough bringing a S’ly change Wed, with the trough deepening as a long angled trough line through the Tasman (see below) and generating a sizey S-S/SE swell into Thurs/Fri with plenty of wind from the same direction. 

ECMWF is far less bullish with  the trough stalling and dissipating during this time frame and not really adding much to the swell sources on hand.

As Ben mentioned on Mon we’re also looking at an ice shelf fetch from a semi-stalled low Sun/Mon which sends some S/SE groundswell arriving Thurs/Fri. Depending on how the trough plays out we could see some good surf from it, or barely notice it under a strong S/SE local wind and swell regime.

While this is playing out another strong E’ly fetch will be flourishing in the Coral Sea/South Pacific adding another pumping swell to the sub-tropics with workable E/NE swells filtering down to temperate NSW.

Looks like a very busy outlook so check back Fri and we’ll see how local winds will co-operate with these swell sources.

Seeya then.