Niña Won't Budge
Two too much
While it's been fascinating to predict then watch the double-dip La Niña event the last two years, what's even more intriguing is watching the Pacific Ocean try, but fail to shake the current oceanic and atmospheric setup.
Whether it be El Niño or La Niña, the signal in the Pacific Ocean usually breaks down (thanks to a rebounding Kelvin wave - more on this later) through our summer and autumn, returning to some form of neutrality during winter. Alas, this year the current La Niña, the second in two years doesn't want to budge.
After warming temporarily through February the Pacific Ocean is starting too cool again and this will extend La Niña's hold on our surf and weather into the middle of the year at least.
Just a quick refresher, La Niña events develop when we get stronger than normal easterly trade winds blowing along the equatorial Pacific Ocean, upwelling cool water in the central and eastern Pacific while piling up warmer water to the west. This warm water fills in and around northern Australia as well as Indonesia, increasing convection and thus rainfall, as well as increasing the chance of tropical cyclones.
El Niño is the opposite, as the easterly trade-winds slacken off and sometimes even reverse, upwelling cool water in the western Pacific while piling up warm water through the central and eastern Pacific Ocean. With the cooler water surrounding Australia there's less convection and hence generally less rainfall.
Neutral years fall in between with steady (neither strong or weak) easterly trade winds blowing across the Pacific and no major heating or cooling sea surface temperatures.
Coming back to La Niña, and with the warm water, increased convection and rising air to our north we see lower pressure develop across the tropics, and this shifts the sub-tropical high pressure belt further south, towards the South Pole during our summer. As a result we see the East Coast opened up to moist, onshore easterly winds, creating more swell activity, but the high pressure belt puts a block across the Southern Ocean, effectively cutting off the southern state's swell sources. It also brings unfavourable east to south-east winds, as many could attest to regarding the last two summers.
So what are the drivers that neutralise a La Niña event and settle things back to the neutral or El Niño status?
In summer, as the warm water builds up across the western Pacific Ocean, we see this water downwelled, producing a warmer than normal sub-surface layer.
This warm water spreads back east under the ocean, known as a Kelvin wave, and shuts off the source of cooler sub-surface water that the stronger than normal trade winds upwell. This occurred during January and February with the Kelvin wave tracking east and then surfacing in the eastern Pacific Ocean (near Peru) as shown in the images below.
Meteorologists sensed the current La Niña was coming to a close, predicting a March exit for 'the little girl'. However, since then waters have started to cool again at and below the surface in the central Pacific Ocean.
This, plus a forecast of stronger than normal easterly trade winds will upwell cooler water again, tipping us below the threshold for La Niña.
And what that means is La Niña will keep on chugging along.
Our weather and surf will continue to be influenced by La Niña all through autumn and possibly even winter. Another factor effecting our climate into winter is the Indian Ocean Dipole, with a negative event seeing warmer than normal water building up around Indonesia, and cooler towards Africa. Negative events usually coincide with La Niña's and this is the forecast for the coming months, with the warm water build up north-west of the country bringing a wetter than normal winter and spring to the country.
So what does this all mean for autumn in your region?
In Western Australia, you only need to look back at what happened last year. As per last autumn and winter, fronts and lows will spawn at the mid-latitudes (meaning further north than usual), which will create more westerly swells. In general this means wet, onshore surf for the Margaret River region with higher than normal rain forecast, but further north at Perth and Mandurah will cope better with lighter winds and plenty of swell.
West swells will favour the South Australian Mid Coast, where they can run the gauntlet into Gulf Saint Vincent, while surfers on Victoria's Surf Coast, who've endured a restless summer, unfortunately won't experience a snapback to normality. A westerly swell regime will see the Surf Coast miss a lot of size, though with winds more from the west than south, at least it'll be clean - gotta look for the positives!
This pattern will remain until winter when the pattern is forecast to slowly break down (images below). Keep in mind the Rip Curl Pro at Bells starts April 10th, meaning the early indications aren't ideal.
For the East Coast it looks like we've got another active few months ahead with the pattern of mid-latitude activity likely to favour southern NSW, while hopefully also providing plenty of energy further north.
Keep an eye on the Forecaster Notes and further articles on the coming autumn, winter and beyond.
Johanna still a Bells backup?
nope - just winki
Locals will be consistently small. We may get a few marginal points swell during April and May but unlikely to be decent sized. La Niña seems to favour our East Coast I’ve found.
When Vic has massive Easter swells we benefit here in TAS unless they are too westerly in nature. But even then if they are massive it can still refract around and then it’s 300 m rides with 50 plus out and everyone saying ‘why’s it so crowded!’
Craig if I'm doing a surf trip from Vic in April should I go to the SA or NSW based on this?
I'd say NSW is probably a safer bet.
Hi Craig, is there precedent for a La-Nina continuing right through a southern hemisphere winter and back into the spring and summer again?
Yes. Last year :-)
What I meant was a La-Nina that doesn't weaken over the winter.
It didn't really. Showed signs of it, with the usual seasonal changes, but the winter of 2021 was very similar to 2020, with a ridge of high pressure persisting over southern NZ.
Actually not last year IB.
Three kelvin waves (two strong, one weak) warmed the Pacific before it started cooling again during July.
This year we've had one weak Kelvin wave and the cooling is kicking back in already.
Time running from last year up top to now at bottom..
Good stuff, Craig. You really know your shit.
Makes me want to be more on top on seasonal forecasting. Quite the shift when my daily focus is on mesoscale nowcasting or regional/countrywide warnings.
In terms of the NZ seasonal pattern, and hence my response to Spud, I still stand by my previous reply. Two very similar winters in a row.
Thanks and yep, gotcha.
I find it really interesting how this chart could almost be pasted on top of itself (ie there was a cooling period in march last year before the 3 kelvin's before winter). Hence the sense of foreboding that a repeat might be in the tea leaves.
I've never looked at the synoptics in the eastern pacific until inspired by your articles (thanks!) Seems that the high pressure is entrenched and would need to budge to lower the equatorial easterlies and consequential warm water pooling in the west. Is that a fair call?
This both sucks and blows.
Good article craig, thanks
What does it mean for Indo season?
Check my answer below regarding early season ID.
Jesus, don't tell me this summer's abysmal run of waves in SA is set to continue! I'm going to take up darts.
A rare win for those of us stuck in Perth this year
WSL - put your permits in for alternative Victoria asap. BELLS IS FUCT.
That could be the most depressing thing I've ever read. Summer on the Surf Coast (ha!) has been beyond sh1thouse and to think there's more of it on the way is enough to......
Off to Noosa for the long-awaited family holiday on Monday (if covid doesn't ground us) and it looks like La Nina is having a 2-week breather especially for us. Yesterday the models were all saying there's a chance. Better be some decent fish about.
So, skip the early season for Indo?
Looks like there'll be lots of mid-period swells for the eastern regions, just less quality groundswells. I'd expect smaller surf to the west as well.
Darts is good, fishing is good. There must be a cranny to shove ones butt in there surely?
Thanks Craig for the deep dive and best of all you're maybe giving a positive forecast for surfcoast beaches ok with west swell if the relentless SEasterlies ever let up
The Sou Easter’s are the real issue, Id take small clean waves gladly
Bring back the drought Huey.
Seems the beneficiaries are NSW, Queensland and NZ which litteraly rub in amazing consistency to all the other states haha.
Not really good news for Perth, last year was the worst winter. Heaps of swell (for Perth) with relentless onshores, maybe the only positive is the beachies had some banks for a change.
apart from the Points here in SE Qld , the beachies have been mostly non existent since Xmas , no banks and mostly onshore , I can't recall a period like this , water quality is c...p atm..
Great insight Craig. You expecting less of the winter south swell that would normally travel below Aus and feed southern NSW (and Vic)?
Into autumn yes but we may see things rectify a bit through winter. Still too hard to tell this far out with confidence.
interesting thanks for the reply!
This is just shit. Summer has been woeful for waves. The bloody south easterlies have been endless. I might have to take up golf if this continues into winter...
Buying an MTB in spring last year was the best thing I’ve ever done. Clocked up nearly 1000km riding in Vic and Tassie
Does this mean more rain for Sydney etc?
I'm growing webbed feet!
Yep, for most of the country.
OK from previous reading I understand this is not directly linked to climate change, is this still the case ?
Also, and this would probably be more relevant if answer to above is NO, are we heading towards this being the new normal ??? I know it is hard to even consider but just to look at worst case scenario... (from Surf Coast POW...)
La Niña no, but we are seeing the westerlies retracting towards the poles as the tropics expand due to global warming.
Climate Crisis in a nutshell
I'm suspecting tides are doing something similar too. Got a chart for that Craig fount of facts that we love
Wow what a great representation of the warming trend we're currently seeing and living through.
Wish i didn't watch it while eating a chilli pie on a humid afternoon!!
It's beautiful work, a friend shared it. The graph has come a long way.
Hard to deny surely?
And yet plenty of people commenting seem to deny it, SL. No doubt, they’ve done their own research.
Stupid is as stupid does.
Wouldn’t mind some blue water and some clean mid period swells on the east coast beachies
What does this mean for the Australia/NZ snow season Craig?
Plenty of moisture which is a plus but it then all comes down to where the cold air approaches from.
And that's not really predictable this far out IMO. If it hits Western Australia then it'll miss our Alpine regions, while if it hits out regions it'll miss NZ a bit.
So yeah can't really help there. Australian snow is very fickle and near impossible to do a long-range forecast on in my opinion.
Fair call mate, cheers
Great article Craig. Thanks
Those old stories about how the waves used to go off; The gold coast / kirra , MP etc surf pumping in the 70's is because it was a triple la nina ?
West Australia in the winters, it blew onshores for months, (my father said these stories too) thats la nina.
Was it also good surf on eastcoast from 98-01 as well ?
Yep. 98-01 was very consistent.
Fuk thats bad news for all ...we don't need any more traveling surfers in N.S.W where chokas now
Thanks, Craig - alongside a weakening Kelvin wave on approach to Peru and a resurgent La Niña oscillation affecting Australia, what does it all mean for Kelly Slater's quest for a 12th World Title?
Love your work. Have learnt so much between swellnet and BOM. So do the strong trade winds drive the Kelvin wave? And these trade winds are part of the MJO?
Will get back to this later.
Yep, so equatorial Kelvin waves are driven by wind stress forcing on the surface. Whether that be the easterly trades or a reversal and westerly wind bursts as through El Niño.
And regarding the MJO, we usually get stronger than normal easterly trade-winds feeding into the MJO tropical wave (just east of it), with westerly winds at the location of the MJO.
So when tracking it, if it's in an active phase, expect easterly winds to the east. This helps the convergence with the westerly winds and increased instability/rainfall.
Will this have any impact on the up and coming Indo season Craig? Im heading over in a couple of months
Ahhh sorry seems you've already answered it above
No probs MD.
What’s happening with the IOD? Will trades blow strong in indo this season or too far far out to tell?
I touched on this in the article but it's expected to dip negative so this will bring lighter trades to the region. A positive IOD brings those stronger, unfavourable (for exposed locations) S/SE-SE winds.
I swore never too go back to indo in a la nina, sept 2007 strong trades and every boat in the playgrounds. Doesn't sound to bad except Nipussy was the only Spot on.
.....Pusssies, with every boat in the Ments!!!
While 2007/2008 was a La Niña year, the IOD was actually + in that 2007 winter so stronger than normal trades.
You’re a guru Craig
From memory (i.e. zero data checking on this one) this means higher % offshores in the morning during winter up here on the Sunshine Coast, once the overnight temp differential flips in favour of the land (lower temp) than the inshore zone (higher).
Or maybe that's just wishful thinking!
Geez, forecast for coastal Nsw over the next week is looking pretty wet. Water has only just started to clear up.
A poor outlook indeed for Surfing conditions in Vic. this autumn 2022. :-(.
Some images from the recent stormy activity..
How's those lefts running down the lawn!
Geez there would be some nervous owners there. Where is the shot with lawns at?
Collaroy in #5? I was living other side of Pittwater Rd right near the worst of it in 2016. Great to see the wall doing exactly what was intended, saving the property and fucking up the beach. #sarcasm
The high pressure over the eastern pacific looks so entrenched. I'm guessing we need that to change to slow down the tradewinds / currents / upwellings. Would that be right? The long term forecast has that whole high pressure setup gaining momentum over the next fortnight which looks like a concern for the east coast over the next month (guessing again!)
Yeah check the wind anomalies for the next 16 days..
Purple = east, red = west. So we usually want westerlies across the south of the continent..
The high pressure forecast for the eastern pacific is still looking intense. Wondering if that spells another wet end of the month on the east coast.
Great article, Craig.
So with a La Nina event, and warmer tropical water temps in the western Pacific, is it fair to say that this type of season will have the greatest effect on Great Barrier Reef with respect to increased coral bleaching.
This seems like a logical assumption to me, but I've seen two separate representatives from GBRMPA being interviewed on mainstream television in the past week, and they both have stated that considering they are seeing high levels of coral bleaching this year, and it's a La Nina, "then just imagine how bad it's going to be when we get an El Nino, and hotter weather."
This sounded arse about to me, I thought I must have mis-heard it the first time, but it was repeated the second day by a different representative.
No doubt multiple factors may need to be considered in the cause of bleaching, but if it was purely being assessed on La Nina/El Nino, would this information be false?
While La Niña does bring the warmer than normal temperatures to the greater western Pacific Ocean, it also brings increased winds and mixing so this might prevent the extended heat and bleaching events.
Where as with El Niño we might see the water sitting more still and with clearer skies, absorbing more solar radiation and heating up that way.
I've not looked closely to the bleaching events regarding ENSO cycles though.
good get Craig! something to do with cloud cover, rainfall and predominate easterly winds from la Nina preventing the likelihood of mass bleaching events that occur in other years. so bleaching during la Nina spells doom!
You do get other impacts associated with La Nina, from all the extra suspended solids and pollution that washes out into the park due to all the rain. So there's less light penetration into the water column, higher nutrient loads etc etc, leading to blooms in "pest" species.
Tough going if you're a coral reef in FNQ.
Agh interesting. Thanks Mowgli.
I think La Niña is also meant to have a higher number of potential cyclones which would help mixing of the water column. However this year it has been strangely quiet with regards to cyclones in the Coral Sea that track towards QLD….any theories on why the lack of cyclones Craig?
There's been a ton of tropical activity in and around Australian waters, with lots of tropical depressions and deepening inland surface toughs bringing cyclonic down pours to SE Qld and Northern NSW.
There was forecast to be "59% chance of more than four tropical cyclones in the western region of the Pacific, which includes countries like Papua New Guinea, Solomon Islands and New Caledonia."
Looks like we've had about four in this region.. (just not close to the mainland).
Here's the outlook from October: https://www.sprep.org/news/nine-to-twelve-tropical-cyclones-predicted-fo...
fascinating article... how does La Nina normally affect swell in Indo?