Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Mon Dec 16th)

Features of the Forecast (tl;dr)

• Small increase in NE windswell Tues with an a’noon or evening S’ly buster
• Spike in S swell Wed as trough moves northwards up NSW coast, with fresh SW-S winds
• Easing S swells Thurs
• 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
• Very uncertain outlook for Xmas week
• Possible deep low forming in Tasman off NSW Coast Xmas Eve with a large S swell developing into Xmas Day
• Low confidence in outlook, stay tuned for next update Wed

Recap

Leftover S swells Sat supplied some 2 occ. 3ft surf at S exposed breaks with only a brief period of offshore W-SW winds before S’lies kicked in. That swell dried up for Sun leaving a small signal of 1-2ft surf under S’ly winds. Similar or smaller today with minor 1-1.5ft surf and early SW-S/SW breezes which are expected to tend variable then NE as high pressure moves into the Tasman.

Still some small leftover S swell around Sat morning

This week (Dec 16-20)

High pressure is now in the Tasman moving NE with a clearing trough off the NSW Coast and a lingering trough line and broad, weak sub-tropical circulation off the Central QLD coast. We’ll see another trough Tues and a vigorous S’ly change with a trough of low pressure deepening and forming a surface low in the Tasman mid week. We’ll see some swell from this pattern, first from the initial short range S swell and then some better quality S/SE swell as the surface low retrogrades from near the South Island back into the Tasman. Read on for details and a sketch of the Xmas week.

Freshening Northerlies in the short run with an early N/NW flow tending N then N/NE and reaching fresh paces after lunch. That should whip up a small amount of NE windswell to 2ft. Latest modelling suggests the trough and S’ly change will hit Sydney mid-late a’noon (4pm) and it should be a vigorous southerly buster, bringing windspeeds in excess of 20kts. 

The fetch winds up o/night Tues into Wed and with fresh S’ly winds on tap, we’ll see an energetic short range S swell up into the 3-5ft range Wed, bigger up on the Hunter and grading smaller away from S facing or exposed breaks. Don’t expect too much in the way of quality but there should be enough swell energy to find a wave at more sheltered spots.

The trough moves rapidly northwards later Wed into Thurs so the initial S swell spike fades back quickly into Thurs, with a moderating S-SE flow. Expect 3ft surf to drop back to 2-3ft during the day at S facing beaches. We may see an inshore SW flow early but a bit of leftover S’ly bump is likely. 

Friday looks interesting. Local winds should lay right down, with early land breezes and light E-SE breezes through the day. The trough of low pressure will have formed a deep low in the eastern Tasman near the South Island and that system is expected to retrograde back towards the East Coast during Thursday. Initially surf looks to be in the 2-3ft range but through the a’noon we should see a nice boost in size as better angled and better quality S-S/SE swell fills in, lifting wave heights up into the 4ft range (few bigger sets possible). Definitely worth pencilling in Fri if you have flexibility. We’ll also see some long range E swell in the mix Fri, background stuff but offering a 2 occ. 3ft wave at very inconsistent intervals.

This weekend (Dec21-22)

Fridays swell increase looks to boost another notch into Sat morning as the low gets a slingshot northwards through the Tasman. Combined with a weak, troughy area establishing over Central NSW that suggests light winds, with a morning W-W/NW flow tending to light NE seabreezes there could be some very good waves around. Expect size under current modelling in the 3-5ft range with some 6ft sets on the menu with an easing trend in play through the a’noon. Background E swell will add small energy into the mix.

Light winds into Sun morning offer great conditions with morning land breezes before winds clock N-NE and freshen in the a’noon. There should be plenty of fun sized 3ft+ surf with a few bigger sets on offer with conditions deteriorating across open beaches in the a’noon. 

Next week (Dec23 onwards)

Very tricky forecast for the Xmas week as a troughy pattern causes lots of model divergence. Expect revisions! 

GFS outlook is the most bullish. It suggests an approaching inland low/trough with a developing NE infeed Mon which would see increasing NE windswell into Mon a’noon. 

The low moves offshore Tues (Xmas eve) with a deep surface low forming off the NSW South Coast (see below). 

Under this scenario we would see a rapid rise in S swell Tues a’noon into Xmas Day (Wed) - up into the 8ft range or bigger with fresh SW-S winds developing. That scenario does seem outlandish for this time of year.

EC has a much more modest front pushing into the Tasman Mon, with a smaller S swell expected Tues, easing into Xmas Day with a provisional size of 3-4ft. 

We’ll update through the week of course. 

Longer term and both models are still toying with tropical developments with the corridor between the Solomons, New Caledonia and Vanuatu looking most likely for development of any tropical depressions. 

Nothing concrete at this stage so stay tuned for the next update on Wed.

Seeya then.