Double-dipping into La Niña
If you've been reading Swellnet over the past few years, particularly our weather analysis articles, you may appreciate how certain global climate indices influence the seasonal surf in Australia.
The biggest player in this space is the El Niño-Southern Oscillation (ENSO) which develops along the equator throughout the Pacific Ocean. The ENSO signal starts to form during spring and influences our weather and surf into summer and autumn.
El Niño (Spanish for 'little boy' as Peruvian fishermen noticed it occured around Christmas) develops under a slackening and reversal of the easterly trade winds across the Pacific, which results in warm water building up in the central to eastern Pacific Ocean, with a corresponding cool water signal developing further west, closer to Australia.
The opposite is La Niña (the 'little girl') which sees stronger than normal easterly trade winds (blowing from east to west) cause an upwelling of cool water along the equator in the eastern to central Pacific Ocean, while warm water pools towards the west - meaning the north-east coast of Australia and around Indonesia.
Neutral events are the most common state that the equatorial Pacific Ocean reverts to, with steady easterly trade winds and convection in the western Pacific Ocean.
Under La Niña setups, the cooler than normal water throughout the equatorial Pacific Ocean suppresses convection (storms/rainfall) in that region while to the west (i.e closer to the Australia) we see increased convection and instability due to the warmer than normal water. This brings increased rainfall to the continent, mainly focussed to the east and north.
El Niños see the opposite occur with a suppression of convection and rainfall in the Australian region (on average - we can still see wet El Ninos), with it enhanced further east towards Central and South America.
Now, not all La Niñas are equal and the same goes for El Niños, they come in different flavours and strengths.
As the the Niña/Niño signal develops across the equatorial Pacific Ocean during our spring, historically the cool/warm water anomaly (measuring the difference from normal) has been positioned towards the east. But over the past few decades we've seen the focus of the temperature anomalies developing further west towards the Date Line (180°).
What this does is shift the general circulation pattern further west, and with La Niña's this means the convection and rainfall is also shifted further west, away from the coastal locations along the East Coast, more inland towards the Murray-Darling Basin and the north-west of the continent.
This variation of the traditional La Niña/El Niño is given the name Modoki (Japanese for 'similar but different').
Following last year's La Niña, and after forecasting the probability of a double-dip La Niña (back to back) event this coming summer, we're currently on the cusp of it coming to fruition.
The difference this year is that we're set to see a bit of a Modoki flavour to the developing La Niña, with the cool sea surface temperature anomalies being strongest further west, towards the Date Line, compared to last year where they were focussed more towards 140-120W. You can see this shift in the two charts below, the first from 2020, the second from 2021. You can also notice the sea surface temperaures in both the Coral and Tasman Sea are a bit cooler than last year.
Last November's classic La Niña signal
This year's developing La Niña Modoki signal
This means that the coming summer and autumn should see moisture focussed more towards central and north-west Australia, however what does it mean for surf potential?
During La Niña, the increased convection and lower pressure across the north of the country shifts the sub-tropical high pressure belt further south during summer. This results in an increase in easterly swell energy across the East Coast, while suppressing the westerly storm track to the polar shelf, further south than normally seen during summer. Meanwhile, the southern states usually experience smaller, weaker swells, and unfavourable winds from the south-eastern quadrant, and that's just what happened across most locations through last summer.
So how does Modoki effect this outlook?
Despite the moisture being focussed more inland, surf wise it looks like we'll see a similar season to the last on the East Coast, with plentiful swell from the east along with more favourable winds (i.e not the usual northerly pattern).
Below is the sesonal forecast (provided by the UK Met Office) for the coming summer months (December, January, February). It shows the probability of lower/higher pressure during the coming three month period.
UK Met Office Mean Sea Level Pressure forecast for December/January/February
Victoria looks to fair a little better, with the position of the blocking high being more favourable than last summer, which was to the south-west of Western Australia. Current seasonal forecasts have it positioned more under Tasmania and across New Zealand which hopefully points to a little more swell action.
Also, with lower pressure through central parts of Australia it'll hopefully tip winds towards a more east to north-easterly bias, with this hopefully also impacting South Australia.
Western Australia looks to be dry and hot with that low pressure anomaly indicating a semi-persistent heat-trough which will bring gusty offshore winds across the surfable regions, while swell wise they should do a little better than last summer with high pressure anomalies forming further west and east of its immediate swell window. This looks to bring energy more from the south-southwest though.
In summary, when looking at the broad scale synoptics it's looking like an active summer ahead . As always, we'll continue to provide updates on the coming summer season in the comments below.
Comments
Unreal Craig. Welcome news after 100+ days confined to shit city breaks with out of control crowds.
Glad to hear that our southern brethren will also have a fair chance at scoring too, at least compared to what seemed like a tough year just gone.
Thanks Craig. Love your work, particularly when it predicts a good season ahead!
Are we just going to trust the science on this??! Shouldn't we get some Facebook opinions?
:P
I think the La Nina pattern is already manifesting quite solidly in the SW Pacific.
Middle of October and the North Coast/SEQLD is yet to get a sustained N'ly episode because alternating high pressure is moving in at the more S'ly latitude Craig mentions above.
all I see are fractals
Ha!
yes that NOAA image looking very Mandelbrotlian
same, look pretty awesome
Exactly Eggman. Note the cold water upswellings which also resemble a very disordered swell, and also clouds that often form at the front of a thunderstorm. Have seen these many times.
Kelvin Helmholtz instability.
Ha, thanks Craig, of course there’s a name for it, and of course you knew what it was. 10/10 :-)
Good ole Kelvin, wonder what board he rides these days?
I thought I was being really cool with fractals but Kelvin takes the cake.
That looks like SE winds where I am. And we'll take that, thank you very much.
Cheers Craig
The blocking high looks pretty suck for us down here though. Curses! Victoria wins we lose.
For those interested in ECMWF's seasonal forecast outlook, here are the probabilities regarding Mean Sea Level Pressure for the according months.
November/December/January
December/January/February
January/February/March
February/March/April
Excellent!! Thank you :)
Absolutely awesome work Craig, you have really enhanced my knowledge of the weather since undertaking this series of articles and I really appreciate the way you've presented everything.
Thanks brother.
Great work!
whoa, thats immense for our surf potential.
Best articles on Swellnet. Love your work!
Great article Craig.
So is that more cyclones but further away?
Here's the cyclone outlook by the BOM.. http://www.bom.gov.au/climate/cyclones/australia/
yeeeww
I can see your future Craig. You’re wearing a brown suede jacket with leather elbow patches and gentling tugging on an antique pipe whilst explaining the vagaries of climate anamolies to the latest round of eager first year oceanography uni students.
“But Professor Brokensha...what about this possibility?”
Ha!
Agree with the appreciation heaped on your efforts, Craig. Learning heaps.
Takeaway from this article for my zone is : Potential for ample East trade swell, less Northerly winds and above average rains without the floods which fucked last summer. Good surfing, good fishing, good growing. Good times.
Nice.
Craig what about the warm current which comes around Gabo Island and comes to the MP? This seems to vary heaps from year to year. 2 years ago is was cold all summer, last year was average and some years it is board shorts till April. Is it tied up with the Nina's and Nino's?
In SA last summer the surf was even more horrible than usual with the winter being pretty sad for most of the time. Will the swell be better this summer than last, ( I know the winds look SE NE as usual as you said)
Swell wise it looks a touch more favourable, but I'd keep your expectations low. Be happy for a peaky Parsons day 1-2x a week maybe..
Snafu in SA summer, thanks for the reply
"Entering Uncharted Waters" Oxfam world social change charity social /climate impact report from Nov 2015....
There is also emerging evidence that climate change affects the El Niño Southern Oscillation (ENSO) cycle and increases the odds of a strong El Niño taking place.
New research says that as the Earth warms, super El Niños may occur approximately twice as often as before – every 10 years instead of every 20 years – and the opposite phase of the ENSO cycle, the so-called La Niña, when the oceanic circulation goes into reverse, may also become correspondingly more frequent and more extreme. Reference#15
The weather impacts of La Niña are more or less the opposite of El Niño, Ref#16 including bringing drier conditions to the American Midwest. La Niña conditions raise sea levels in the Western Pacific, which increases the destruction caused by storm surges there.
Some new research suggests that a ‘new normal’ will come into being that corresponds more to La Niña, but punctuated periodically by more frequent, extremely hot El Niño events.Ref# 17
Oxfam Report & references from 2015 below
https://oxfamilibrary.openrepository.com/bitstream/handle/10546/578822/m...
Great report
Could be horror on the West Coast for VL again sadly.
The horror has already started. about 2/3 weeks ago.
Just shift your focus further west . Months of ESE with ENE - LAGO's sounds like heaven to me .
Yeah I’ll take that
Hello Southey
booya
La Niña causes an upwelling of ocean nutrients= plankton = abundant sardines in South America; so a fertile time.
Eating fish increases the chances of pregnancy.
So more waves for us on the east coast of Oz & more babies in Peru.
You don’t think the enhanced fertility of fish consumption will be offset by the contraceptive effects of sardine breath?
Get a good catch, go to the market; hava few drinks & then a Ceviche (a very popular dish in Peru).. recipe: raw fish + lime juice & wait 5 minutes.
https://en.wikipedia.org/wiki/Ceviche
Hey Craig, great article thanks. Which part of the anomaly comes first? The sea temperature or the wind? I would have thought the sea temperature has more effect on the wind than vice versa. If so do ocean currents first drive the sea temperature?
Great question.
It's the wind.
There is a sub-surface cool water signal that travels from west to east but this needs to be upwelled and the stronger bursts of easterly trade winds are the catalyst for this.
Once it starts going though it's a positive feedback loop with the warmer water to the west causing that rising air which then strengthens the easterly trade winds further, upwelling more cooler water etc.
The correlation between the wind driven surface currents (blue line) and the sea surface temperature signal (red line) is shown clearly below.
You can see the blue line dip negative (westerly flowing currents from the easterly trade winds) which then brings the opposite signal in the sea surface temperature a couple of months later (rising in the Western Pacific)..
Both last year's and the coming La Niña can be seen.
Thanks, that all makes sense.
Criag, if surface water is pushed to the left by winds as explained in one of your earlier articles wouldn't warm water from the north of the equator fill in or is surface water pushed to the right north of the equator thus allowing for the upwellings to occur. BTW great articles and well explained.
Aghh, it's to the left in the Southern Hemisphere, but to the right in the Northern Hemisphere, hence why you're seeing those eddies north of the equator spinning clockwise.
The Coriolis force works in opposite directions in either hemisphere.
The "Eckman Transport" from memory? Lovin this thread btw. Great work
Sorry, anti-nina here ....Dribs is always crap with those se winds summerlong. Maybe an odd waits or robe foray.
Pro-vaxxing though... it's a coming. Love the science Craig
upload image
I find this graph interesting in a few ways. One of them is that the La Nina years seem to bring out the "good ol' days" call from the elder statesmen on the Gold Coast. Seems to represent it nicely that the 70's actually was a glorious decade.
GFS got your memo Craig and jumped straight on board
Bingo.
How apt that I’m reading this as a seriously black thunderstorm passes overhead.
We’ve had a batch of these this Spring, normally don’t see them until December or January.
Of course, may or may not be directly related, but, you know. Weather!
Seems to be slightly linked but also feeding off the negative Indian Ocean Dipole (which is now weakening). Great show this evening!
So does this mean less winds from south south west and more from east over summer in sw WA? Also how does this effect the inland temp in the desert east of the west coast? Will that see more rain from tropical lows?
Hi Craig
Did I ask stupid questions?
Sorry, missed this Bob.
It's hard to be specific but yeah it looks like stronger winds from that SE-E direction in the mornings, still S/SW into the afternoons. And yes hotter more inland.
Thank you very much. I thought I missed something that was obvious.
Not sure if you timed this article with the current set-up Craig, but the Pacific Basin right now has almost got the perfect La Nina set-up.
E'ly Tradewinds from end to end.
troughs of low pressure where they are supposed to be.
And for Aus- the missing link- which is strong high pressure at southerly latitudes which can tele-connect warm, moist air from the West Pacific warm pool to the East Coast.
It's a thing of beauty at the moment.
And its only October!
Last year we didn't get the set-up until first week of December.
Yep, looks like it's already kicking into gear which is great to see!
I was waiting for the BOM to pull the trigger and that upgrade to alert was all I needed to push go.
The combo of a Negative IOD will bring the La Nina on earlier . With it contributing to the (SOI) Southern Oscillation Index ( the atmospheric component of of ENSO ) , due to the higher likely hood of lower Pressure anomalies over Nth / NW Aust .
The ITF will cause a positive feedback on all this as it sees the Pacific wide sea level differential even out a little , the resulting rainfall in SE Asia will also contribute to stronger cool water downwellings with more fresh / turbid water infiltration .
These downwellings months before the subsurface cold pool will form and add to the " bank " of cool water that can be entrained into its flow West to east in the depths . That is the first indicator that there will be a strong body of equatorial sub surface cool anomaly to draw on when and if the surface winds will help draw it to the surface in the East .
Sometimes higher subsurface anomalies Nth and mostly Sth of the Equatorial zones can reduce their impact as they are dilluted prior to surfacing in the East . This is where regional surface warm anomalies can influence each years intensity . Think of the (IPO) Interdecadal Pacific Oscillation , the (PDO) Pacific Decadal Oscillation , (NPGO) North Pacific Gyre Oscillation which inturn then can effect the (QBO) Quasi-biennial Oscillation { an upper atmosphere pattern that is linked to the Frequency of of Craigs favourite SSW's } . Its here where researchers are madly trying to work out how much Climate change is contributing to its knock on effect to ENSO .
Thanks Southey, yeah lots of research going into where things go from here re the IOD (trending more positive events) with the western Indian Ocean warming faster than the east and anywhere else in the world if I remember quicker. Then the frequencies and intensities of Niña/Niño's and chucking in the possible shift to more Modoki events.
Excellent work Swellnet
Thanks for sharing everyone, the amount of knowledge here is very impressive. If only the other forums on Swellnet could be conducted in this manner, eh!!!
Still having cool starts to the day here on the Tweed which is great. My appreciation of the intracacies and interconnectedness of our Biosphere workings just keeps on growing. The intelligence that is behind it is just mind boggling. Thanks Swellnet.
How will this effect west coat NZ?
One would think less groundswells from the south-west but with more favourable winds, so good for the beaches.
Great article thanks swellnet
Another great article, ta.
Thanks crew, always exciting and interesting to watch unfold!
Craig - Incredible work .
If you and Southey can get together and work out , and tell us mere mortals when and where the surf will be ON you should get a big bonus .
‘This year's developing La Niña Modoki signal’ chart / picture is a thing of beauty.
How is it that those cold upwelling regions actually look like waves? Stunning
Craig - It seems that there are SN watchers in the US .
NOAA's 2021 Winter Outlook outlines wetter-than-average conditions for the Northern U.S., mainly in the Pacific Northwest, northern Rockies, Great Lakes, Ohio Valley, and western Alaska. The report said widespread drought in the western half of the U.S. would continue to be monitored.
"Consistent with typical La Nina conditions during winter months, we anticipate below-normal temperatures along portions of the northern tier of the U.S. while much of the South experience above-normal temperatures," said Jon Gottschalck, chief of CPC.
Accumulated rainfall for the next fortnight on the whole east coast is looking pretty solid.
Yep, the tap is turning on..
The confluence of moisture feeding in from the north-west and north-east is saturating the country at the moment. Thanks to the negative Indian Ocean Dipole in the Indian Ocean (weakening) and La Niña signal in the Pacific Ocean (strengthening).
Great stuff, Craig.
Does a weakening Dipole usually coincide with a La Niña and vice versa ie stronger Dipole and El Niño like the bushfires summer two years ago?
And is Vicco’s November winter linked or are they two separate things?
A negative IOD usually couples with La Niña's, but the IOD signal peaks in late winter/early spring while Niña is through late spring/early summer.
The 2019 setup was due to the record positive IOD, then the Sudden Stratospheric Warming (SSW) event which saw the westerly storm track lifted up into Australia during summer.
The lack of moisture arriving through spring from the north-west caused soil moisture levels to reach record lows, on the back of drought and then the lift in the storm track due to the SSW brought westerly and north-westerly winds drawing heat that was building up inland down and into the south-east of the country.
Worst case nightmare situation really.
Vicco is cooler than normal due to the increased cloud cover and moisture preventing inland from heating up.
Ah so Qld hot as usual but inland south of ‘the Brisbane Line’ not heating up. Hence northerlies middle of next week but still only sneaking above a max of 20 for Melbourne.
Thanks! Really enjoy these pieces.
For those interested, the most recent MSLP probability for Dec/Jan/Feb..
Big block holding for WA, excellent setup for the East Coast, with the southern states smaller (semi-blocked) but with workable winds..
Awesome, thanks.
Is the extent of the high pressure anomaly in the central / eastern pacific normal for La nina?
Looks impressive
That's a good question and I would say similar. With La Niña's we see the sub-tropical high pressure ridge moving south and more instability, lower pressure shifting south with it.
And then gradually we realise local conditions never exist in isolation. We look west and see that Victoria’s weather comes from the East Indian Ocean, which comes from the West Indian Ocean, which comes from Africa, which etc etc until we’re all the way back to Mallacoota!
It’s fascinating because it’s global and in a constant state of change.
So you're saying it all originates in Mallacoota.
If a butterfly flaps it's wings at Bastion Pt...
well, its still early days I guess, but it seems my hope for this year's La Nina to bring more rain to my part of the world (south-east Mary Valley), after missing it last year, is beginning to happen. October was really good, about 240mm, and it keeps on coming (about 50mm so far this month. Lots of good soaking rain, steady for many hours, with heavier bursts in between. Looking like more to come later and into tonight. Glad the ground is getting recharged, but I can concur with the ticks issue as being discussed under the latest SEQ/NNSW forecaster notes - mongrel things, I've had multiple over the last few weeks. But then stoked that the neighbour's Guinea Fowl have decided to return to grazing through my place - I hear they are good tick eradicators, so I hope they are doing their job well
Have you had a look at the National Satellite Rain Radar. That system? Is it insanely large? Stretches from Darwin to Melbourne ..
(Is there a how to post a photo tutorial)
Yeah it's nuts..
I'll have a fresh article up tomorrow.
Somewhere a bufferfly flapped it's wings and now look at this shit-storm ... of storms. I'll tune in tmrw
Say it ain't so. Cries from the southern states herald out across the hillside.
The long-range forecasts are holding a weak La Niña signal into next summer. I'll keep a close eye on developments.
Holy shit! Maybe time for Southern surfers to take up golf instead. Although I'll certainly take another year of it if you're offering.
Do you mean that next summer will be another La Nina summer... or that that current La Nina pattern will hold all year, potentially destroying Autumn and Winter surf?
Yep current one is weakening but the signal might not full break down and linger into next summer.
Nah shouldn't influence you guys that much into autumn/winter as the sub-tropical ridge pushes back north and cold fronts encroach from the Southern Ocean.
Ok sweet. I can deal with an ordinary summer, obviously prefer different but as long as autumn and winter gives us plenty then so be it.
A triple dip?
I really hope not, SE winds are never good for here but a triple dip and no Indo holidays is a bleak outlook. I'm so lucky to have had 3 weeks in WA in October, made it in out before the doors shut. The surf wasn't good but it was great to get away in such a beautiful state..
Triple threat!
Craig, if you continue to bring this this la Nina shit into the forecast, I'm gonna cancel my subscription....I'll do it, I swear..... ;)
Haha, sorry WaG.
3 waves of covid and 3 waves of the nina, the conspiracy plot thickens, with no nina vaccine yet.
Look at who benefits! Big farmers! Haha.
Haha.
hah. very good.
Coming back to this article, where the Modoki twist of the La Niña was mentioned, it looks like the rainfall anomalies match up to that.
With Modkoi we see the cold water anomalies in the Pacific spreading further west along the equator, pushing the warmer water further west, hence focussing the rainfall further west and into inland Australia and across the North West.
Here are the rainfall anomalies for November, December and January.
This is a brilliant article Craig, bang on with the predictions of more rain further west, look how smashed the central parts of the country are currently getting, and also with how much swell the east coast has been receiving. Where it has slightly missed is for us poor sorry souls here in SA and i'm guessing Vicco too getting absolutely smashed by relentless Sou Easters and very minimal swell this summer. Great work though mate.
Thanks Stef! It's all panned out favourably, I even mentioned the tendency for winds from the north-east across Victoria which has played out though without the swell unfortunately.
Here's hoping we have a classic autumn in to winter to make up for this summer, haven't been down south in months but that's understandable being a weekend warrior, all the offshore days have been mid week! Haha!
It's frustrating when it gets into that cycle as it seems to be a weekly repeat and if not aligned with it, you get skunked.