Sydney Hunter Illawarra Forecast by Steve Shearer (issued Wed Jun 19th)

Features of the Forecast (tl;dr)

• Still solid but slowly easing into Thurs with swells more SE and offshore winds
• Nice mop up day Fri with small, fun SE swells
• Rebuild in bog standard S swell Sat PM, peaking into Sun with SW-S/SW tending S’ly winds Sat, more S’ly-S/SE’ly on Sun
• Easing swells next week- should be a few fun days of S/SE swell and offshore winds
• Few fluky swell sources on the radar long term but all low confidence- see notes below

Recap

Still very vigorous surf yesterday with surf falling out of the sky in the 6-8ft range and the occ. 10ft set still being reported in the a’noon as a reinforcing pulse filled in. Conditions were mostly clean under an offshore flow. Still solid this morning, although down from yesterdays peak with 6ft+ sets from the S/SE and offshore winds from the W, expected to tend SW and then clock back to W through the day. We will see a slow easing trend start to kick in during the a’noon.

Still plenty of strong swell energy hitting the coast this morning

This week (Jun 19-21)

995 hPa low still sitting in the Central Tasman, but the supporting high pressure cell has slipped in underneath the low and as a result we’re seeing a slowly diminishing fetch and easing pressure gradients both in the Tasman and along the coastal fringe. Incredibly the low remains in the Tasman, right through the week and into the weekend, re-energised by an approaching cut-off low and trough and a new supporting high pressure cell. In comparison to the current event it’s a much more subdued system but we will see a rebuild in S’ly swells from it over the weekend. Details below.

In the short run, no change to the outlook. We’ll see slowly easing surf through tomorrow with offshore winds, which should lay down and tend variable before possibly tending NW as the interior low/trough approaches. Still plenty of swell, with 4-5ft of size widespread and a few 6ft sets on offer at exposed breaks. 

Winds out of Cook Strait and adjacent to the west coast of the North Island look better aimed at Tasmania (see below) but we’ll still see some SE-E/SE energy show on Fri, along with easing S/SE swells. Expect 3 occ. 4ft surf Fri morning , dropping back to 2 occ. 3ft during the day. Winds look good. W-W/NW through the morning and then tending W/SW-SW through the a’noon as the trough exits and the stationary Tasman Low starts to wind up again. Should be a great mop up day to end a memorable week.

This weekend (June 22-23)

Redeveloping winds and swells this weekend as the reinvigorated Tasman Low tightens pressure gradients along the coast and in the Tasman. Sat morning looks the best of the winds, with a morning W-W/SW flow. Those winds will tend SW-S and freshen and eventually clock around S-S/SE in the a’noon and make surface conditions pretty ugly. We should see 2-3ft of mix of S and E/SE swells before a rise in shorter range S-S/SE swell in the a’noon pushes surf back up to 4-5ft, bigger on the Hunter. Sheltered spots will be considerably smaller but there should be a workable compromise to be found if you aren’t too fussy about wave quality.

Bigger and windier on Sun with a fresh S-S/SE flow and only a brief window of SW winds likely north of the Harbour. Fairly sizey but short period S-S/SE swell should be up over 6ft at S exposures, significantly bigger on south facing coastlines but very messy and wind affected. Again, you’ll need to seek wind protection where wave heights will be reduced. 

Next week (June 24 onwards)

It’s generally an easing trend next week, although there a couple of swell sources in the South Pacific worth keeping an eye on, favouring the sub-tropics at this stage.

The general trend will be down though as the incredibly persistent Tasman Low drifts over towards New Zealand with a weakening fetch. We should see some workable S-S/SE swell through Mon with improving winds, likely at least in the 3-4ft range.

Easing further into Tues with winds tending to light offshores and a’noon seabreezes. 

We may see a little bump in SE swell either later Wed or Thurs as remnants of the low near the South Island provide last one pulse . No great size expected and models aren’t in terrific agreement. We wouldn’t expect anything bigger than 3ft but winds should be offshore as a front approaches from the west, so it may be worth pencilling in at this early stage. Let's see how that looks Friday.

There is some polar low activity favoured by GFS and ECMWF next week (timing is different) which may supply some long period S swell mid/late next week. Models are also suggesting a deep sub-tropical low in Tongan longitudes right on the edge of the swell window, which looks to supply some long period E/SE swell , likely down to about Seal Rocks, although some E swell may filter down into Central areas from the Hunter to Northern Beaches.

EC is also suggesting a possible low north of the North Island last next week, again right on the edge of the swell window. They all look pretty low percentage events for Central/Southern NSW at this stage so we’ll flag them for now, and see how it’s shaping up on Fri.

Seeya then.