Sydney Hunter Illawarra Forecast by Steve Shearer (issued Fri May 17th)

Features of the Forecast (tl;dr)

• Strong front and developing low pressure trough sees sizey S swell and fresh SW-S’ly winds Sat
• Sizey but easing S swells Sun, tending more S/SE in the a’noon with improving winds
• Rebuild in S swell likely Mon with freshening SW winds
• Plenty of S swell Tues, tending to more favourably angled S/SE-SE swell in the a’noon and Wed
• Likely easing swells Thurs
• Possible rebuild in S swell Fri- low confidence
• Likely easing swells and light S winds next weekend

Recap

Small mixed bag yesterday to 2 occ. 3ft with a S swell showing late in the day. Today is seeing some long lines from the S with S groundswell to 3 occ. 4ft and the odd bigger set at S magnets, smaller 2ft elsewhere. Nice conditions with morning offshore W-W/NW winds expected to tend SW likely after dark as a front pushes NE up the coast and a trough of low pressure develops.

Long period S swell in the water this morning

This weekend (May18-19)

An angled trough of low pressure forms off the NSW Coast o/night and quickly moves out into the Tasman Sea. Compared to Wed’s notes windspeeds look a smidge weaker, but the fetch forms a better aligned SE arm around the trough line through Sat. That will see the initial windy short range S swell still building from 4-5ft in the morning to 6-8ft in the a’noon with bigger 10ft surf on S facing reefs and bommies. Morning SW winds will eventually clock S’ly at strong wind strength (there is a gale warning so expect stronger gusts). Surfable options at more protected locations will see less size.

Initial S swell will ease into Sun, with better angled S/SE-SE swell generated by the more favourably aligned fetch in the Tasman Sat. Expect easing S swell to 6-8ft Sun morning becoming better angled surf to 4-5ft in the a’noon. Winds from the W/SW-SW will tend S/SW through the day with an easing trend so there should be some more exposed options in play- if not perfectly clean. 

Next week (May 20 onwards)

As mentioned Wed, it now looks likely a cold front pushing into the Tasman Mon will reinforce the weekend low pressure trough and form a broad low in the Tasman (see below), backed by another massive high in the Bight,  with several pulses of swell from this system.

The front itself should generate another pulse of S swell Mon as winds freshen from the SW-S/SW and surf rebuilds to 4-6ft at S facing beaches, smaller elsewhere.

S’ly winds persist Tues and Wed, although we should see morning sou-westers develop as the low in the Tasman drifts away and pressure gradients ease enough for seasonal land breeze effects to take hold. Plenty of swell both day with Tues in the 4ft range occ. bigger set and swell direction tending more S/SE through the day as swell trains from winds around the Tasman low make landfall.

Wed should bump a notch with SE swells to 4-5ft occ. bigger set on tap.

There’s still some model divergence around the strength and positioning of the low so we might need to finesse wave heights up or down on Mon but it won’t be anything too significant- we’re now in medium/high confidence territory for these outcomes. 

We’ll see easing swells for the back half of next week as the low moves away and high pressure ever so slowly inches towards and then past Tasmania. 

We may see some local S swell later next week from a small trough.
More likely we’ll see lighter S’ly winds next weekend and some S’ly groundswell from intense polar lows which look to be steered SE of New Zealand into the prime Tahitian swell window during that time frame.

We’ll check it all out again on Mon, as per usual.

Until then, have a great weekend.