thermalben

Curveball-o-rama: TC Oma swell outlook on hold

Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Monday 18th February)

Best Days: Everything's on pause right now. Can't see a good day this forecast period with any clarity right now. 

Recap: Saturday saw a peaky mix of fun S’ly swell around 2-3ft, plus some E/NE swell of a similar size. Light winds gave way to afternoon NSW sea breezes. Unfortunately, Sunday didn’t pulse in size as expected from the E/NE (despite the Mid North and Northern NSW coasts building nicely), maintaining 2ft waves through the morning before increasing slightly to 2-3ft throughout the day. Early light winds were then followed by fresh NE winds. We’ve seen the E/NE swell combine with a peaky NE windswell today, offering 2-3ft waves across the coast. A small S’ly swell is also providing occasional 2ft+ waves to south facing beaches. A brief period of light N’ly winds have freshened from the NE throughout the day. 

Small punchy NE/E/NE swell combo at Maroubra this arvo. Shame about the wind.

This week and weekend (Feb 19 onwards)

Today’s Forecaster Notes are brought to you by Rip Curl

Before we get into the discussion re: TC Oma, it’s looking like today’s small south swell will ease from Tuesday onwards. Not that there’s a lot of size anyway. 

A series of poorly aligned Southern Ocean fronts will provide minor background southerly groundswell all week, and a shallow southerly change will bring about a local windswell increase once it pushes through on Tuesday morning (building into the afternoon, easing through Wednesday, low quality sets peaking around 2-3ft+). Don't get your hopes up.

Righto. On to TC Oma. 

It’s been a fascinating system to watch over the last few days, mainly because of its slow moving nature in and around the Vanuatu region.

As for swell potential, there’s a lot of mis-information in the model guidance, for a couple of reasons. 

Firstly, TC Oma lies to the north of New Caledonia, and although it looks (on the charts) that there’s a clear swell window through to at least SE Qld (and at a pinch, various parts of the NSW coast), in fact there is an otherwise sneaky, hidden obstacle - the French archipelago known as the Chesterfield Islands, lying approximately 550km NW of New Caledonia. They are sufficiently broad in spatial coverage to present a significant barrier to any E/NE or NE swell from locations upstream (i.e. close to Vanuatu). 

Therefore, with the Northern Beaches data point registering the leading edge of cyclone swell on Tuesday (0.2m @ 14.9 seconds NE, around 6am), I have to call bullshit: TC Oma won’t really clear the New Caledonian swell shadow until tomorrow, and even then most of the core fetch won’t be ideally aimed within our swell window. It's simply picking up swell energy forecast by the model that doesn't have the appropriate archipelago masking.

In fact, for the next few days once TC Oma enters the swell window, it really won’t be sitting in a prime position for our coast (fetch alignment will be on the wrong quadrants), so I’ve downgraded my thinking from Friday’s notes: we’re probably looking at an eventual spread of small to moderate E/NE swell, mainly source from the supporting ridge to the south, but probably arriving later in the week. Actual long period NE swell is now unlikely to eventuate.

But, to be honest most of the forecast period from Thursday onwards is a write off anyway.

And this is because of a recent major divergence in model guidance. 

On Friday, the general consensus had firmed that TC Oma would following the climatological convention, briefly push into SE Qld coastal waters, and then be deflected to the south-east enroute to New Zealand, where it’d undergo extra tropical transition. We’d see some kind of NE swell from the early stages, tending E’ly ahead of a strong SE swell off the latter stages of the low near New Zealand.

This outlook held into Saturday and early Sunday. Confidence continued to build.

On Sunday evening, the world’s leading atmospheric model (ECMWF) bucked the trend: keeping TC Oma off the SE Qld coast for a few days and then actually tracking it north, ahead of a coastal crossing mid-next week.

This is quite the curveball. 

So, I’ve been patiently waiting for the latest model update (hence the delay on these notes). And they seem to be holding steady with this divergent view. ACCESS G is also siding with EC, so it's now impossible to find a line of best fit.

In the short term, this won’t have a material impact on the forecast for SE Qld and Northern NSW coasts over the next few days, as they’ll see strong cyclone-derived swell regardless. But the variations in surf potential for Southern NSW is non-insignificant: large, or small. Sure, the EC solution whereby we see little cyclone swell may be supplemented by (eventually) some unrelated SE swell from a short wave trough moving into the south-eastern Tasman Sea. But forecasting this is no better than rolling a dice right now.

So, instead of elaborating any further, let’s take another pass on Wednesday.

I’ll also update in the comments below tomorrow if anything new comes to light. But for the meantime: the chances of a signifiant NE tending E’ly swell (and then a large follow up SE swell) from TC Oma is on hold. 

Comments

thermalben's picture
thermalben's picture
thermalben commented Monday, 18 Feb 2019 at 6:20pm

I bet the 06Z update (in around 5-6 hours time) will probably reinstate the weekend's model trend, and I'll look like a fool. But hey, live by the sword, die by the sword, etc.

donweather's picture
donweather's picture
donweather commented Monday, 18 Feb 2019 at 6:24pm

Huey is good at making us look like fools!!!

thermalben's picture
thermalben's picture
thermalben commented Monday, 18 Feb 2019 at 6:30pm

Actually half-wrote today's notes expecting EC to drop its silly northern jaunt, and come back in line with GFS.

Had to scrap the entire thing.

millsy351's picture
millsy351's picture
millsy351 commented Monday, 18 Feb 2019 at 6:51pm

Haha, GFS & EC have been at odds for days now and both are staying staunch. JTWC also notes it too; has NFI right now as a result of the divergence, either.

deckstrus's picture
deckstrus's picture
deckstrus commented Monday, 18 Feb 2019 at 6:24pm

faaaaaaark

NewcastleWaterman's picture
NewcastleWaterman's picture
NewcastleWaterman commented Monday, 18 Feb 2019 at 6:38pm

If you really cared about scoring great waves you would just head north once a system presents itself.

mick-free's picture
mick-free's picture
mick-free commented Monday, 18 Feb 2019 at 6:49pm

We been pretty horny on this update all day Ben.

"(0.2m @ 14.9 seconds NE, around 6am), I have to call bullshit:"

LOVE your work.

Mick Free FIFOFOMO

thermalben's picture
thermalben's picture
thermalben commented Monday, 18 Feb 2019 at 7:09pm

Let's all be thankful I'm not forecasting for Gary G's coast.

Gary G's picture
Gary G's picture
Gary G commented Tuesday, 19 Feb 2019 at 12:52pm

It's always offshore and well groomed in Gary's coastal regions

You and me, Gary, ain’t nothing but mammals so let’s do it* like they do it on the aerobics channel

*faceys

mibs-oner's picture
mibs-oner's picture
mibs-oner commented Monday, 18 Feb 2019 at 7:41pm

Coming up your way this weekend Mick let’s get a couple.

Mibs

mick-free's picture
mick-free's picture
mick-free commented Wednesday, 20 Feb 2019 at 4:53am

Mid North or Mantown?....either way doesn't look that good? I'm thinking loading up the rescue boat and heading north.

Mick Free FIFOFOMO

mibs-oner's picture
mibs-oner's picture
mibs-oner commented Thursday, 21 Feb 2019 at 6:16am

Mid north mate. If you hand around let me know.

Mibs

pancakecollaroy's picture
pancakecollaroy's picture
pancakecollaroy commented Monday, 18 Feb 2019 at 6:53pm

Let us pray for GFS model but both have onshores for the duration...lines beneath the chop is better than chop !

batfink's picture
batfink's picture
batfink commented Monday, 18 Feb 2019 at 10:45pm

Fair call on the bullshit Ben. No way we're getting any cyclone generated swell. Just trade wind stuff. Until anything gets south of new cal it ain't gonna produce anything here. Still expecting large east and south swells from this and the southern ocean low merger, but hey, that was 6 hours ago!

geoffrey's picture
geoffrey's picture
geoffrey commented Tuesday, 19 Feb 2019 at 8:57am

latest update on here has a solid ENE swell in about 10 days. thats where they have hovered this whole month, 7-10 days away. its almost like they are deliberately dangling a carrot to upset us. i need to get a wart cut out of my foot and have been putting it off for ages due to said carrot.

belly's picture
belly's picture
belly commented Tuesday, 19 Feb 2019 at 9:24am

TMI :-)

geoffrey's picture
geoffrey's picture
geoffrey commented Tuesday, 19 Feb 2019 at 9:34am

can post pics if you want

belly's picture
belly's picture
belly commented Tuesday, 19 Feb 2019 at 9:49am

I may have (read did) suffered from the same affliction... Note past tense, touch wood.

Island Bay's picture
Island Bay's picture
Island Bay commented Tuesday, 19 Feb 2019 at 9:46am

Latest (18Z) GFS run has done a switcheroo: Oma stays put off QLD :-)

maka2000's picture
maka2000's picture
maka2000 commented Tuesday, 19 Feb 2019 at 10:39am

Do you think the coogee cake will work this sunday? or it's a bit wrong swell dirrection for it ?

joesydney's picture
joesydney's picture
joesydney commented Tuesday, 19 Feb 2019 at 10:57am

The wind will be crap so even if there swell cloey bombie will be blown out. If the swell does come head down to Sandon or Redsands for a look

mibs-oner's picture
mibs-oner's picture
mibs-oner commented Tuesday, 19 Feb 2019 at 6:39pm

That’s the way Joey send every kent down to us

Mibs

maka2000's picture
maka2000's picture
maka2000 commented Wednesday, 20 Feb 2019 at 9:10am

don't worry, there're plenty of novelty spots will be available for this type of wind this weekend, so keep your point to yourselvs.

choobpig's picture
choobpig's picture
choobpig commented Tuesday, 19 Feb 2019 at 7:19pm

Fuck off joe

joesydney's picture
joesydney's picture
joesydney commented Tuesday, 19 Feb 2019 at 7:47pm

Yeah sorry I exposed those "secret spots" to the rest of the world. Here's my tip get your postcode tattooed on your forehead so everyone know you're a real local and not a blow-in.

South Coast Chomper's picture
South Coast Chomper's picture
South Coast Chomper commented Tuesday, 19 Feb 2019 at 10:54pm

Joe ya off ya f#%ken lemon spread. You might shake the blokes dick next to ya when you’re having a slash but we aren’t that accommodating down here.

maka2000's picture
maka2000's picture
maka2000 commented Wednesday, 20 Feb 2019 at 9:14am

ah-haaaaaa... tell it to aquabumps dude who exposes your places to the rest of the world, and don't get surprised why whole brasil has suddenly migrated to the coal coast .

mibs-oner's picture
mibs-oner's picture
mibs-oner commented Thursday, 21 Feb 2019 at 6:17am

YTC

Mibs

belly's picture
belly's picture
belly commented Tuesday, 19 Feb 2019 at 12:49pm

Any updates Ben?
The bom 4 dayer has been updated. Seems to be a slight axis rotation on the Thursday 10pm forecast to send a pulse southward..

thermalben's picture
thermalben's picture
thermalben commented Tuesday, 19 Feb 2019 at 2:13pm

Nothing to add right now. Regular analysis/updates aren't really worth the effort at the moment given the massive changes from model run to model run.

the-u-turn's picture
the-u-turn's picture
the-u-turn commented Tuesday, 19 Feb 2019 at 4:11pm

Ben, 10pts to you. The honesty (and humility) in your forecasting is worth every cent. Many Thanks ...(now just tell me, and of course only me, just when & where to go),

The U Turn
...a little Aloha goes a long way.

Horas's picture
Horas's picture
Horas commented Wednesday, 20 Feb 2019 at 12:34am

And please hold my hand,please

Horas

tubeshooter's picture
tubeshooter's picture
tubeshooter commented Tuesday, 19 Feb 2019 at 8:30pm

If it happens it happens , If it doesn't it doesn't . I was a little skeptical from the start. re the hype and big calls.
Having said that , the show isn't exactly over, and, I,m not leaving the stands just yet.
This is what anticipation is all about , waxing longer boards in case , listening for that rumble late at night ,,,,
The hunt is still on.

eastcoastbuoy's picture
eastcoastbuoy's picture
eastcoastbuoy commented Tuesday, 19 Feb 2019 at 9:30pm

get on a plane and head to Norfolk Island

eastcoastbuoy

billie's picture
billie's picture
billie commented Tuesday, 19 Feb 2019 at 9:40pm

CAAAAARRRRRRNNNN HUUUUEEY!!!

Billie

Gilbo23's picture
Gilbo23's picture
Gilbo23 commented Tuesday, 19 Feb 2019 at 11:18pm

Let's go.

Gilbo23's picture
Gilbo23's picture
Gilbo23 commented Tuesday, 19 Feb 2019 at 11:21pm

At this stage, I'm thinking a strike mission to the gold coast, but going either direction to avoid crowds.