Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Mon 19th May)

Features of the Forecast (tl;dr)

• Surf remaining elevated from the E/SE-E through Tues into Wed as trough hovers off MNC with onshore SE-E winds easing into Wed
• Low confidence for Thurs depending on evolution of trough, likely easing winds and plenty of E swell
• Low confidence for Fri but light winds likely, with E swells
• Weekend outlook depending on how trough/low evolves, winds likely tending N through NW with E’ly swells, possibly sizey
• E’ly swells persist into next week
• Good odds of a strong S swell event next week as front/low pushes into Tasman- check back Wed for more info on size and timing

Recap

Saturday offered up some small, fun E swell in the 2-3ft range with clean conditions under light winds. Surface conditions deteriorated Sun as a  front/trough brought increasing S’ly winds which made a mess of most spots, although we did see a building trend in mostly short range S swell to 3-4ft through the a’noon. Not much to recommend this morning with rain and strong S/SE winds, which will tend SE through the day. There’s a raw mix of S and SE swells to 6ft+ (still building) on offer but very little quality about it. We’ll see more inclement days ahead as a weather event plays out across most of coastal NSW.

Building, raggedy surf as coastal trough deepens in Tasman

This week (May 19-23)

A very unstable, dynamic synoptic chart this week with a large high (1034hPa) moving from the Bight through Victoria, with a coastal trough deepening off the Mid North Coast on the leading edge of the high directing very moist onshore winds across Central NSW, extending up into the sub-tropics. We still have some model uncertainty over the fate of this trough. Fridays forecast of a low or ECL variant was downgraded into a persistent trough over the weekend but there are still model runs suggesting a low will form in the trough line this week. With so much uncertainty still around be prepared for major revisions as we move through the week. 

In the short run conditions remain unfavourable with a mod/fresh onshore SE flow, tending E’ly through the day. Plenty of raw, mid period E/SE swell in the ocean, in the 6-8ft range with very few clean or even semi-clean options apart from some novelty waves.

The onshore flow look to continue into Wed but there is some suggestion from weather models we may see a weaker, troughy area develop about Sydney to the South Coast. It’s possible in this weak pressure gradient we may see some lighter land breezes develop before light S to SE or even E’ly breezes kick in. No shortage of E’ly swell with the fetch aimed up at the NSW MNC, we’ll see size in the 5-6ft range, likely just softening a touch through the a’noon.

Forecast confidence drops significantly as we move into Thursday. Lots of outcomes on the table. We may see a new trough develop off the Sydney coast with a developing SW-S flow as a new high ridges in from the Bight. The trough off the MNC-North Coast may deepen into a low and track southwards, bringing an increased E/NE swell later Thurs with strong S’lies developing. Or the whole pattern may just wash out  into a generalised onshore flow with easing swells. Stay tuned and we’ll try and update below the line before Wed’s notes. 

Similar low confidence for Fri as we have model divergence over the fate of the trough/low in the Tasman. European model and ACCESS favour the trough for form a low which moves southwards with offshore winds developing either Fri or Sat AM. GFS is less bullish with an E’ly tending NE’ly flow and smaller swells from the E/NE. 

This weekend (May24-25)

Same very low confidence applies to the  weekend f/cast, so take current wave model output with a grain of salt. About the only thing we can be sure of is swell will be from the E through E/NE. Either solid from a low moving southwards through the Tasman or modest from an E’ly fetch off the top of the high. For the sake of it, we’ll pencil in 3-4ft and adjust up or down as we get more clarity though the week. 

Winds are likely to tend N’ly through NW’ly over the weekend as a major low-pressure approaches from the west. 

Next week (May 26 onwards)

A broad E’ly fetch developing through the South Pacific will provide background E’ly swells into next week (see below).

That's likely to be strongly overshadowed by strong S swells as a front and parent low moves aggressively into the Tasman early next week (see below).

Too early to have confidence in size or timing but early indications are looking like it will be significant S swell event, likely developing Tues/Wed. 

Lot’s of short em uncertainty to get through before then so check back Wed and keep tabs on below the line comments as we track this dynamic Tasman Sea weather event. 

Seeya Wed!