Analysis : La Nina watch

Craig Brokensha
Swellnet Analysis

While there've been local indicators, such as heavy, persistent rain events, we're now officially on La Nina watch for this coming summer.

The Bureau of Meteorology made the switch earlier this week which puts the chance of La Nina developing over the coming months at 50% (double the the average likelihood). NOAA's Climate Prediction Centre are also on board with 40-50% chance of La Nina forming.

If we take a look at the sea surface temperature indicators across the equatorial Pacific (see image below), a clear cooling has taken place in the eastern and central equatorial Pacific Ocean, while there's been some warming in the western Pacific. This setup usually drives a feedback loop, with strengthening easterly trade-winds across the Pacific Ocean, promoting further upwelling and cooling off the South American coast.

Global Sea Surface Temperature Anomalies (notice cool water across the central and eastern equatorial Pacific Ocean)

Easterly trade-wind anomalies (difference from normal) are slightly stronger and the sub-surface temperature profile is also pointing towards a La Nina event. That being cool water extending deep below the sea surface to the east, with warm water throughout the water column to the west.

Whether this continues and develops into a La Nina event is still uncertain, though as mentioned, most climate models are trending towards either a neutral or La Nina event.

If we do see La Nina developing it will mean an increase in rainfall across central and eastern Australia. The last significant event being 2010/11 when we saw wide-spread flooding across many locations. That was the summer of the Brisbane floods, when the rising waters caused havoc in the Lockyer Valley, 2010 was also the wettest calender year for the Murray-Darling Basin.

With the current forecasts only just reaching La Nina thresholds, a repeat of 2010/11 is unlikely, if it occurs at all.

Here on Swellnet we've frequently discussed the Indian Ocean Dipole (IOD. The difference between this and El Nino/La Nina is that the IOD, which develops during winter, effects rainfall across central and inland Australia through our spring and early-mid summer. While El Nino/La Nina effect rainfall throughout the entire year though focussing on the central and eastern half of the country.

So what does this mean for surf potential?

In 2015 we penned an article looking at the effects on mean significant wave height during El Nino/La Nina. That article used data sourced from a 2011 study by Mark Hemer, “The wind-wave climate of the Pacific Ocean”.

During La Nina years the mean significant wave height increases through the Coral Sea and northern Tasman Sea , largely owing to more frequent easterly trade-swell. However, there's a reduction in swell size for Tasmania and Victoria that's linked to blocking highs setting up across Victorian latitudes.

Change in Mean Significant Wave Height (m) compared to neutral conditions

While having more swell is all well and good, it's the local winds that will make or break a good surf season, and that's yet to be seen.

So sit tight over the coming months as we monitor the developments through the equatorial Pacific Ocean.

Comments

freeride76's picture
freeride76's picture
freeride76 commented Thursday, 25 Jun 2020 at 11:22am

It'll be interesting to see whether this developing La Nina or even tendency towards one alters the trade wind flow back to normal seasonal patterns or whether we get another toxic summer with the dry northerly pattern prevailing.

burleigh's picture
burleigh's picture
burleigh commented Thursday, 25 Jun 2020 at 1:08pm

Oh man, those northerlies were horrible.

donweather's picture
donweather's picture
donweather commented Thursday, 25 Jun 2020 at 1:28pm

I'll second that!!!

With winter so far that's had more summery looking patterns than the norm, I'm not counting my chickens for a good spring this year!!

freeride76's picture
freeride76's picture
freeride76 commented Thursday, 25 Jun 2020 at 1:51pm

well spring is spring.

Normally the northerly pattern would start to relax during December- or November in a good year- and we'd get Tradewinds through the summer.
The new normal is the northerly pattern running right through summer.

Cetus's picture
Cetus's picture
Cetus commented Thursday, 25 Jun 2020 at 10:50pm

New normal or stochastic cycles?

freeride76's picture
freeride76's picture
freeride76 commented Friday, 26 Jun 2020 at 5:19am

good question.
doesn't seem to be a truly stochastic system, but who knows.

tiger's picture
tiger's picture
tiger commented Thursday, 25 Jun 2020 at 2:11pm

The last few years have also seen unseasonal prolonged spurts of noreasters through both autumn and winter. This year has seen more traditional winds through the S and W quadrants with just a few single days of prefrontal N winds. And we've seen a good run of waves. One thing I've noticed during the bad run of the last few years is the belt of high pressure, rather than nice big separated high pressure systems. I reckon we're looking in better shape going into this summer.

freeride76's picture
freeride76's picture
freeride76 commented Thursday, 25 Jun 2020 at 4:17pm

yeah, the highs have been in much better shape and located at the correct lats.

Solitude's picture
Solitude's picture
Solitude commented Thursday, 25 Jun 2020 at 2:27pm

This is easily the most consistent year (waves, wind, banks) I can recall for the past 10 or so.

I'll be expecting a few more decent swells or a couple of all day offshores this winter and something good to round out September if we're lucky too. Howling northerlies from Oct through Nov. Hopefully a nice trade pattern returns by early December. Not asking for much (ha!)...….but the way its going it wouldn't be out of the question.

indo-dreaming's picture
indo-dreaming's picture
indo-dreaming commented Thursday, 25 Jun 2020 at 2:46pm

Havent even read it yet, but i know this is going to be a good article, these articles are what makes Swellnet one of the best surfing related sites on the internet.

Please Stunet give me an ignore button for Talking Turkey, Shatners Basoon, Dale Cooper, Factotum, Pupkin, and any new fake profile he decides to create.

indo-dreaming's picture
indo-dreaming's picture
indo-dreaming commented Thursday, 25 Jun 2020 at 2:54pm

Ok La Ninas IMHO are better than La Nino's

Good for Vicco beachies and ok for Indo not like La Ninos that cause southerlies for months in Sumatra

Please Stunet give me an ignore button for Talking Turkey, Shatners Basoon, Dale Cooper, Factotum, Pupkin, and any new fake profile he decides to create.

Craig's picture
Craig's picture
Craig commented Thursday, 25 Jun 2020 at 3:51pm

El Nino Indo, and the southerlies in Indonesia are linked to the Indian Ocean Dipole and it's positive phase. There are correlations between El Nino and + IOD events but not always.

carpetman's picture
carpetman's picture
carpetman commented Thursday, 25 Jun 2020 at 6:02pm

Any more details and range on the figure above?

Why the significant difference in the Caribbean and the Indian ocean in the figure?

I know they say the correlations are only weak, but I imagine they modeled the globe, not just the Pacific, for comparison.

I assume its NOAA source? Any for IOD and the indian ocean?

Craig's picture
Craig's picture
Craig commented Monday, 29 Jun 2020 at 7:44pm

Re the Caribbean, during El Nino trade-winds are stronger across that region, hence the increase in size.

The study above is centred around Australia and the Pacific Ocean so don't have more data for the Indian Ocean sorry. Will try and dig deeper for it.

carpetman's picture
carpetman's picture
carpetman commented Tuesday, 30 Jun 2020 at 8:57am

Ok, thanks Craig.

surfstarved's picture
surfstarved's picture
surfstarved commented Thursday, 25 Jun 2020 at 4:29pm

Niña
Niño
Option/alt+N then N on a Mac keyboard. Just saying. It's a small thing but it shits me to tears.

As you were...

Don't let the bastards grind you down

Johknee's picture
Johknee's picture
Johknee commented Thursday, 25 Jun 2020 at 5:47pm

Cálmate, surfstarved! There's enough la Niños and el Niñas to go around!

juegasiempre's picture
juegasiempre's picture
juegasiempre commented Friday, 26 Jun 2020 at 6:26am

I certainly don't care. But for correctness is would be los niños and las niñas. Plural and gender and all that.

shoredump's picture
shoredump's picture
shoredump commented Saturday, 27 Jun 2020 at 8:37am

You’ll never find this level of gramma nazi on any other surf related website ever. Another reason I subscribe

scottishsponger's picture
scottishsponger's picture
scottishsponger commented Sunday, 28 Jun 2020 at 8:18am

Or grammar Nazis.

dawnperiscope's picture
dawnperiscope's picture
dawnperiscope commented Thursday, 25 Jun 2020 at 6:57pm

The heat map in the central / southern pacific is an interesting feature (and the corresponding increased heights in central america)
The lows in that region at the moment look like they are tending towards a stretched out south - north fetch.
I didn't really take any notice at the time but I imagine the june 2006 mexico swell before the search comp was formed out of this pattern. Covid dreaming...

Ride on

Craig's picture
Craig's picture
Craig commented Monday, 29 Jun 2020 at 7:45pm

That would be more so linked to the positioning and alignment of the Long Wave Trough rather than the current Sea Surface Temperature developments.

arcadia's picture
arcadia's picture
arcadia commented Thursday, 25 Jun 2020 at 10:40pm

Where I am in Japan, strong La Nina's aren't the best news. The sub tropical ridge tends to extend over the Philippines into the South China Sea, inhibiting typhoon development and pushing the ones that do form too far west to produce decent swell.
Better news if you're a skier though.

dawnperiscope's picture
dawnperiscope's picture
dawnperiscope commented Friday, 26 Jun 2020 at 8:36am

Probably not related to this, but the article got me looking at the charts and it seems like all the southern oceans are pretty lined up at the moment. I spose its just the normal winter pattern?

Ride on

palmymick's picture
palmymick's picture
palmymick commented Friday, 26 Jun 2020 at 6:57pm

I read that the SAM is heading negative too
That’s should push the southerly storm track further north, and combining with a neutral ENSO or La Niña should bring more snow?
And if these storms are closer does that mean less long period swell and and more dicey winds?

Craig's picture
Craig's picture
Craig commented Monday, 29 Jun 2020 at 7:52pm

La Nina hasn't formed yet, but yes the SAM is dipping strong negative, though the frontal activity linked to this is being aimed into WA and SA rather than Victoria/NSW. It looks (the SAM) to weaken once the frontal activity moves east over to Victoria, with another strong dip in 1.5/2 weeks time.

So snow wise, while a negative SAM is favourable for bringing the fronts further north and across the country, it's all down to luck on where they are focussed, and right now it's WA.

Remigogo's picture
Remigogo's picture
Remigogo commented Monday, 29 Jun 2020 at 8:26pm

Spot on Craig!

Keep up your great work...

palmymick's picture
palmymick's picture
palmymick commented Tuesday, 30 Jun 2020 at 10:28am

Cheers Craig...thought you'd be all over it!
I dont think that's enough to get snow on Bluff Knoll!!
I'll keep my fingers crossed for August. Models seem more positive late in the season.

sc1southern's picture
sc1southern's picture
sc1southern commented Saturday, 27 Jun 2020 at 8:05am

We have had the best Autumn and early winter swell patterns for as long as I can remember. I’ve been surfing for 35 years and can only remember 1-2 years where it had been similar. Consistent swell with reasonable winds on both coasts and more than fair share of waves. Crowds though have never been so bad and that is unfortunately the fault of our lifestyle being sold out to every Tom, Dick and Fukwit. Seems as though Covid has ruined many a thing over the last few months but the ocean has had no worries delivering the goods.

FrazP's picture
FrazP's picture
FrazP commented Saturday, 27 Jun 2020 at 1:01pm

I'll second that Southern. Great conditions by and large all year but circus like crowds. I completely understand why but doesn't make it any easier to like.

Love these articles and commentary. The only thing i really wish is for our surf reporter to stop saying the surf is great when the reality is the conditions are great but surf is crowded straight handers

MartinNow's picture
MartinNow's picture
MartinNow commented Saturday, 27 Jun 2020 at 6:07pm

Covid was a surfest here:)

MartinNow

Spuddups's picture
Spuddups's picture
Spuddups commented Saturday, 27 Jun 2020 at 6:31pm

It’s been fairly epic here in NZ for the last couple of months. Swell from all directions. Good winds.

southey's picture
southey's picture
southey commented Sunday, 28 Jun 2020 at 2:27am

Interesting . This looked like a lock in the sub surface for a long time . Funny how the professionals at BOM and others inputting data into the seasonal models are so slow to publically recognise the potential of the La Niña .

The subsurface and another milder version of the Nth East Pacific's ( the blob ) of warmer surface waters may temper this La Niña 's strength . ( Atleast thats what the SST feed in signals are telling me) . Buts it's too early to tell what reinforcing effects the resultant Rossby wave of this burgeoning La Niña will deliver .

Another note after we saw a halt to the earlier chances of a strong Negative IOD forming is that the South China Sea already charged which maybe captured from early IOD activity , but maybe early signs of the La Nina's influence on the Indian .

If the ITF does its thing and these Cool upwellings continue to rapidly spread in the NW Indian Ocean then regardless of La Niña's strength , Australia will see effects similar to 2010/11 . As it was the double influence that made that year's ENSO cycle stand out . If you look at the Anomaly SST chart Craig showed at the top of the above article you can see the seed of NW Indian upwelling . And in a few short days its now significantly bigger/ broader .

Shout out to Surfstarved , us PC plebs just wait for people like yourself to do the hard work so we can cut and paste for correct Granma ;-)

The true story here is whether or not this El Viejo is up for what Hughie delivers from all this anti-El Niño .!!
Peace out , this Gringo is going to move to higher ground and crawl back under a rock .

" SA's Reserve Capacity "

yahabo's picture
yahabo's picture
yahabo commented Tuesday, 30 Jun 2020 at 3:48pm

"However, there's a reduction in swell size for Tasmania and Victoria that's linked to blocking highs setting up across Victorian latitudes."
Assume this means the same scenario for SA?

Craig's picture
Craig's picture
Craig commented Tuesday, 30 Jun 2020 at 3:59pm

Looking at the charts above, it looks about average, if not a touch bigger regarding west swells through the Bight. Swell direction is hard to gauge there though but seeing the flow on effects from WA, I'm inferring it's west in nature.

yahabo's picture
yahabo's picture
yahabo commented Tuesday, 30 Jun 2020 at 4:30pm

Cool thanks Craig. Appreciate the response.

SI's picture
SI's picture
SI commented Wednesday, 1 Jul 2020 at 9:11am

I dunno, but if you look at that map about half way up or more on the right side, there’s some pretty cool looking waves!!

Barrelrider