South East Queensland and Northern New South Wales Surf Forecast (issued Wednesday 5th February)

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thermalben started the topic in Wednesday, 5 Feb 2014 at 4:59pm

South East Queensland and Northern New South Wales Surf Forecast by Ben Matson (issued Wednesday 5th February)

Best Days: Thurs: building combo of SE swells in SE Qld. Fri: decent SE groundswell for the Mid North/Northern NSW coasts (and SE Qld too), but with lighter winds in the south. 

Recap: Mainly residual SE trade swell in the SE Qld region, whilst exposed south facing beaches along the Northern NSW coast have picked up an additional short range south swell associated with a gusty change that pushed into southern NSW on Tuesday.

This week (Feb 6-7) 

There’s been a few changes since Monday’s forecast. TC Edna has indeed redeveloped in the Coral Sea, in fact it’s now located east of 160E so is now in the AOR (Area Of Responsibility) of the Fiji Met Bureau. TC Edna is now a Cat 2 cyclone, and expected to intensify slightly over the next 24 hours.  

Unfortunately, TC Edna is now tracking S/SE and expected to continue this trajectory over the next couple of days (see JTWC chart below); also with a little more speed than previously thought. This will reduce its potential as a primary swell generating system over the next couple of days, however we’ve had a couple of other curveballs thrown into the mix to dampen the forecast enthusiasm.

On Monday I also discussed the potential for yet another tropical low/cyclone to form within the active Coral Sea monsoon trough throughout this forecast period. This still looks set to happen over the next 24 hours (the tropical low we're watching is just SE of PNG), however model data now suggests the developing system will track rapidly SW towards the Central Queensland coast over the coming days (completely outside of SE Qld's swell window).

However the development of this second system is also having an effect on TC Edna. Right now, a strong ridge is building across the southern Coral Sea - and interacting quite well with TC Edna - however as this second cyclone starts to take shape, and the ridge encroaches further north along the Qld coast, it appears that the ridge will weaken and then split in half between the two systems (just off the SE Qld coast). This disruption within our immediate swell window will negatively impact the surf potential over the coming days.

This is also having a (modelled) flow-on effect for the rest of SE Qld’s swell windows out into the South Pacific into the weekend and next week, which is a shame as there’d previously been several days of good agreement between the models on a favourable broadscale pattern setting up for the region.

However, I won’t write it off completely just now - let’s give the models a few days to sort themselves out (they always seem to wig out when there are multiple cyclones in the progs). 

Anyway, this still doesn’t detract too much for the surf forecast for Thursday and Friday however I will slightly peg back projected wave heights a little. Exposed beaches - that’ll really be open to a strong S/SE breeze - should still see bumpy 4-6ft waves, but most of the regional points will be much smaller, building into the 3ft to maybe 4ft range during Thursday. Protected points (such as Noosa) will be even smaller again, owing to the predominant southerly component in the swell direction. As for the Northern NSW coast - fresh SE winds will write off most locations on Thursday. 

But, there’s one other source of swell that’s looking like delivering something worthwhile on Friday - and this will probably favour the Mid North Coast (due to lighter winds, thanks to this coast being located further away from the Coral Sea ridge).

Back last Friday I mentioned the possibility of a cut-off low developing in the lower Tasman Sea this week (see notes here), with a resulting SE groundswell on the cards for this Saturday. Over the weekend, model data held true so Monday’s forecast remained on track.

Today, we’re now finally in a position assess satellite data of the low (which formed late yesterday) and the good news is that it’s looking very strong, and close to the model predictions of five days ago. As per the image at the bottom, the OSCAT returns are showing a very tight system with embedded wind speeds of 50-60kts at the core of the low. It’s not aimed perfectly towards the East Coast however the back (southern) flank is in a pretty good position, along with the near-stationary nature of the fetch since last night that’s expected to persist into tomorrow. The only change to the forecast is that due to slightly stronger winds around the low, and its closer position to the mainland (than modeled last Friday), the swell will arrive a little earlier.

The leading edge of this swell is expected to reach the southern NSW coast late Thursday and should fill into the Northern NSW coast overnight, and SE Qld on Friday morning, reaching a peak here in the afternoon. Wave heights should reach a solid 4-5ft+ at exposed spots however the bulk of the Gold and Sunshine Coasts will be off-axis to the swell direction and will therefore see smaller wave heights (there’ll also be some existing trade swell in the mix in SE Qld too). The SE Qld points will be your best on Friday anyway due to a moderating SE airstream, however the further south you head towards Sydney, the lighter the local winds will be. So just keep this in mind if you’ve got a road trip in mind.

This weekend (Feb 8-9)

Saturday will be on the backside of all of these swell events, and at this stage it looks like we’ll see early light SW winds in most regions tending moderate SE during the day. Smaller waves and similar winds are expected on Sunday. The only variable here is the potential second Coral Sea low/cyclone, which is forecast by at least two models to impact the Central Queensland coast during the weekend. If the model output changes for this system we’ll see a corresponding change in the weekend wind forecast - but probably not the surf forecast. 

Next week (Feb 10 onwards)

Nothing major on the cards for next week at this point in time. The remnants of the Tasman low (mentioned above) are expected to linger near the North Island of New Zealand for a few days, and there’s a reasonable expectation that we’ll see a modest SE fetch develop in SE Qld’s swell window over the weekend. This - in associated with a rebuilding ridge throughout the southern Coral Sea - should maintain small levels of trade swell across the region from about Tuesday through Friday of next week. But no great surf is expected at this stage. Check back on Friday for more details on the longer term outlook.

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mundies Wednesday, 5 Feb 2014 at 7:29pm

Mmmm. Coming into season. Thanks for the update Ben.

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mitchvg Thursday, 6 Feb 2014 at 12:28am

Gotta start kite-ing

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mitchvg Friday, 7 Feb 2014 at 12:29am

Who can spot the cut off low's groundswell? Pretty easy, but it doesn't seem like it is a distinct entity as it is shown on models...

So what's happening? Are discrete pulses pumped out or is it kinda just spraying a swell train as it migrates eastward?

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thermalben Friday, 7 Feb 2014 at 12:07pm

Yeah it's a weird one and not what I was expecting to see on the buoys. It's more akin to a growing tradeswell on the Gold Coast. I've been a little suss on the MHL buoy data over the last few months (under various circumstances), but haven't been paying close enough attention to know whether the pattern is regular, or if it's a brief anomaly.

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donweather Friday, 7 Feb 2014 at 1:57pm

Looking at the animation of the byron buoy, it looks to me as if the S/SE groundswell kinda came in a few pulses from around 10pm last night until mid morning this morning.

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mitchvg Friday, 7 Feb 2014 at 6:56pm

Yeah, unfortunately I wasn't able to test the groundswell-i-ness of it for myself :( how about you DW?

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mitchvg Friday, 7 Feb 2014 at 6:57pm

thermalben wrote:

I've been a little suss on the MHL buoy data over the last few months (under various circumstances)

Won't forget how the MHL guy said that it's a dark art hahaha