Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Wed Dec 18th)

Features of the Forecast (tl;dr)

• Moderate S swells Thurs AM, easing a notch PM with mod S-S/SE winds
• Quality S-S/SE swell redeveloping Fri a’noon as winds ease back
• Quality S/SE swells Sat with light offshore W-W/NW tending NE winds
• Lots of fun leftovers Sun from the S/SE with light winds tending N/NE and freshening
• Small, background E swells in the mix Fri-Sun
• Dynamic outlook for Xmas week
• Possible deep low forming in Tasman off Gippsland Coast Mon- Xmas Eve with a sizey S swell developing Xmas Eve and into Xmas day
• Increasing confidence in outlook, stay tuned for next update Fri

Recap

We saw some workable NE swell yesterday, building to 2 occ. 3ft in the a’noon before a S’ly change hit in the a’noon. Short range S swell and S’ly winds are making for a very low quality surf today in the 3-4ft range at open beaches, smaller into more protected locations. 

Short range raggedy S swell only for the keen

This week (Dec 18-20)

We currently have a deepening trough of low pressure developing behind a front which is bringing fresh and gusty S’ly winds up the NSW coastline, extending into the sub-tropics through the day. This trough of low pressure deepens into a surface low in the Tasman and is expected to track in a northerly direction through the short term. The initial spike in short range S swell will be reinforced by better quality S/SE swells late this week into the weekend. Still some very juicy possibilities for Xmas week, particularly Xmas Day as model runs start to coalesce on the probable  outcome of a deep low in the Tasman which generates sizey S swells. Read on for details.

In the short run we’ll see S swell stabilise into tomorrow morning with S’ly winds tending S/SE at moderate paces. Winds should be lighter S/SW-S inshore early with patches of SW breeze on the Northern Beaches. Surf will still have some S’ly bump about it, so don’t expect clean conditions. Size in the 3-5ft range at S facing beaches early, will slowly back down later in the a’noon. Smaller surf will be available at more protected locations.

Winds start to ease on Fri as pressure gradient relax across the NSW Coast. A light SW morning flow should tend to light SE breezes before clocking around E/SE to E/NE-NE in the a’noon at light paces. We’ll see S swells to 3ft initially with better quality S/SE swells filling in after lunch to 3-4ft with the occ. bigger set. Conditions won’t be perfect but there should be plenty of workable options under a light onshore flow. A small signal of long range E swell offers an occ. 2ft set in the mix as well.

This weekend (Dec21-22)

Sat still looks good under light morning land breezes tending to light E/NE-NE breezes through the day, getting up a little from mid-a’noon. Good quality mid period S/SE-SE swell in the 3-4ft range with occ. 5ft sets offers up plenty of opportunity across open beaches to reefs and points. Long range E swell throws up the odd 2-3ft set into the mix.

Easing swells into Sun with early NW breezes tending light, then moderate NE in the a’noon as weak high pressure sits in the Northern Tasman and a trough lingers off the coast. Fun sized SE swells to 2-3ft (occ. bigger set) early, ease back during the day. 

Next week (Dec23 onwards)

Very dynamic synoptic set-up as we move into the Xmas week. First, looking to the north a weak monsoonal low looks to form off the North QLD Coast and drift into the Coral Sea. Under present modelling the system remains weak and only generates small E’ly swells for the sub-tropics. We’ll monitor that in case of any further development. 

To the south, things look to escalate quickly during Mon as a low forms off the Gippsland Coast. We may see some NE windswell develop into Mon from winds feeding into the developing low. We’ll pencil in 3ft surf for Mon, under an initial NW flow before the low brings a S’ly change during the day. A late kick in new S swell is on the cards.

A rapid deepening of the low o/night Mon into Tues is now progged by major weather models as it moves slowly E-E/NE into the Tasman (see below). 

Under current modelling the resulting fetch of SW-S gales would generate a spike in new S swell Tues up into the 5-6ft range, bigger on the Hunter under a mod SW-S flow tending S-S/SE during the day.

If the low behaves as currently modelled we’d expect a further increase into Xmas Day into the 6-8ft range, bigger at S magnets and bombies under similar winds, easing during the day as the low slowly moves Eastwards.

Surf then slowly backs down through Boxing Day then eases more rapidly into the weekend with light winds expected tending N’ly and freshening.

Further ahead, more troughiness in the Tasman is expected into the New Years week. We may see another low pressure form, although models are in poor agreement. 

Let’s see how that looks Fri, as well as another look at this potential Xmas Day swell. 

Seeya then.