Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Wed 22th Dec)

Forecast Summary (tl;dr)

• Small mix of SE swell Thurs, blended with small, longer period S swell hampered by SE winds
• More small SE/ESE swell Fri with a small pulse of longer period S swell PM and light E'ly winds
• Small blend of surf on XMas Day morning with a SSE groundswell filling in during the day, mostly light winds tending NE and freshening, possible slack winds due to a'noon storms
• Inconsistent SSE groundswell Boxing Day favouring S facing beaches with a gusty S'ly change likely in the morning
• Increasing short range SE swell likely Mon PM
• S swell likely late Mon/Tues
• Chunky SE/ESE swell likely Tues-Thurs with mod/fresh SE/ESE winds. Dependent on position of low/trough, stay tuned for revisions

Recap

Not a great deal of surf to talk about since Mon with most of the region seeing a weak 1-2ft signal from a mixed bag of small swell trains yesterday. The Hunter coast fared a bit better with some 2-3ft waves and with generally light breezes there were surfable options on hand. A slight uptick in size from the E today coincided with a brief window of offshore winds before S’lies kicked in, allowing for some clean 2ft options, with the experience enhanced by a push of very warm water from the East Australian Current. Small waves are always better in boardies.

Small, glassy options with warm water

This week (Dec 22-24)

Very weak pressure gradients everywhere as we continue to meander through this troughy, doldrums pattern with small, weak surf. It’s not unusual to get this pattern around the Summer Solstice as seasonal atmospheric/oceanic changes start to manifest. Currently, the last of a series of fronts is passing well to the south of Tasmania, weakening as it enters the far Southern Tasman Sea. A rare, stalled low well south of the South Island has aimed a fetch of severe gales back towards the East Coast over the last 24-36 hrs, with travel distance and fetch length limiting swell production to a small, long period pulse over Xmas. 

In the short run a NW/SE angled trough and weak high pressure ridge will set-up a regime of SE/ESE winds off the Central NSW Coast. While these winds look weaker than models indicated on Mon they are still going to be the major factor for surf quality, producing a general onshore flow that will degrade surf quality for the rest of the working week. One small caveat to that wind forecast is the possibility of another small, coastal trough forming off the Illawarra region during Fri which may create some local fluctuations in wind direction, including glass offs and lighter windspeeds compared to the rest of the f/cast region. Keep tabs on local winds Fri. 

Swell will be small for the rest of the week anyway. A small blend of E’ly swell in the 1-2ft range, with a slight kick in new S swell later Thurs offering up some 2ft sets at S swell magnets, likely hard to utilise in the prevailing SE flow.

Friday doesn’t look much better. More small, marginal surf from the E, with some traces of longer period S swell, topping out at 2ft at S facing beaches. Quality is likely to be very low under the prevailing SE/ESE flow, with the possible exception of the Illawarra region if the small surface trough forms near there. It’s low confidence stuff with marginal outcomes so if you’ve got pre Xmas stuff to get done Friday looks good for that.

This weekend (Dec 25 - 26)

Christmas Day won’t be one for the history books as far as surf goes but there should be a rideable wave on hand as our rare SSE groundswell starts to fill in during the day. Small traces of S swell and background E/NE swell will hold surf in the 1-2ft range Xmas morning at exposed breaks, with a light NW flow favouring S angled beaches and coastal alignments. Sets from the S/SE should fill in through the morning but it’s wise to keep expectations pegged for this swell.

It’ll be Lully and slow due to the travel distance, mostly 2ft, with the odd bigger 3ft set at S swell magnets. Expect increasing NE winds through the day as a complex, inland trough system approaches from the West. 

Another lingering trough line may see winds drop out south of Jervis Bay during the a’noon. Thunderstorms may also disrupt mesoscale winds through the a’noon.

Boxing Day sees a pattern change with a S’ly change due which starts a new, dynamic synoptic chapter. Surf wise we’ll be looking at easing surf from the S/SE, and possibly a later increase in new short range S’ly windswell depending on how quickly the S’ly flow ramps up off the NSW South Coast. Best odds is to get in early, where a SW flow is mostly likely, apart from the Hunter coast, which may still see lingering NW flow before the change hits. Expect inconsistent 2-3ft sets at S facing beaches through the morning.

Next week (Dec 27 onwards)

A strong front passes below Tasmania over the Xmas weekend with the leading edge of a very strong high pressure ridge behind it. That quickly establishes the strong S’ly flow up the NSW coast during Sunday into Monday. That pattern quickly interacts with a complex upper-level trough system tracking towards the coast from the sub-tropical interior, likely forming a coastal trough and possible surface low during Mon. 

There’s still a high degree of uncertainty over where this trough/low will form, anywhere from the SEQLD coast down to the Mid-North Coast has been suggested by recent model runs.

Either way, the block pattern of a slow moving dominant high will set up a very strong cradling effect for any trough/low that forms, and the ridge itself will see fresh SE winds establishing through Mon, likely into the middle of next week.

Surf-wise we can expect a steep ramping up in size through Mon, mostly from short range SSE/SE swell generated by winds in the Tasman sea, overlaid with longer period S swell later in the day from the passage of the front on the weekend. Size is likely to build from 3ft up into the 4-5ft range during the a’noon.

Plenty of size is expected through Tues and Wed, as the proximate fetch of strong E/SE winds aimed at Central NSW remains slow moving. A mix of long period S and dominant mid-period ESE swell in the 4-6ft range across exposed stretches of coast is expected, depending on the position of the trough/low. It’ll be raggedy and raw due to the fetch proximity and local winds so expect to seek shelter and lose some size, though even sheltered locations should see plenty off surf due to the swell direction.

The second half of next week should see conditions start to settle as the trough/low system migrates E away from the coast, allowing local pressure gradients to ease. 

With model divergence escalating through the second half of next week it’s likely predictions will need to be revised heavily on Fri or Mon. The most likely outcome is a slow ramping down in size from the E through E/SE with a lingering E’ly flow, possibly tending to morning land breezes late next week.

Plenty more tropical developments look in store for the first week in Jan, with models suggesting a tropical depression or even cyclone crossing Cape York Peninsula, possibly reforming into coast hugging low early in the New Year. 

We’ll be looking at plenty of wind and swell to finish off the year, with lots more action coming up to start it.

Check back Xmas Eve for a final look at the Xmas weekend and last week of 2021. Seeya then.