Indian Ocean Dipole Event Set To Arrive Early
We’ve got some earlier than normal developments underway across the Indian Ocean basin, and it doesn’t paint the prettiest picture for western Indonesian locations.
As the Eastern Pacific slowly cools down from El Niño and likely transitions to La Niña through late winter/spring, we’ve got a weak cool signal developing in the eastern Indonesian region - immediately north-west of Australia.
This looks to be the start of a positive Indian Ocean Dipole (IOD) event, with it possibly being strong and peaking through winter.
The Indian Ocean Dipole is an index measuring the differences in temperature across the Indian Ocean, varying between positive, neutral, or negative in phase.
A positive IOD event is characterised by cooler waters off Indonesia and warm waters off eastern Africa. This difference between cold and warm drives stronger than normal southeast trade-winds that flow from high pressure across Indonesia, towards low pressure generated by the heating in the west - see image below.
More often than not it becomes a positive feedback loop, with the stronger than normal trade-winds inducing upwelling across the Indonesian region while piling up warmer water to the west. This creates a stronger temperature gradient, and hence even stronger trades.
Under a negative IOD event, warm water forms around Indonesia with cooler waters off eastern Africa, resulting in weaker than normal trade-winds and bouts of north west winds across Sumatra.
In short, positive IOD events limit surfing options away from the more exposed breaks of Indonesia thanks to the relentless southeast wind when otherwise winds are more light and variable. It also brings cooler, greener water (due to the upwelling), which along with the associated wind chill, means extra rubber is needed.
If you're heading to Indo this season, particularly from mid-season onwards, best you pack some rubber and when the trades kick look for protection (Shield)
There are a couple of interesting points regarding the likely early onset of this positive IOD event. Firstly IOD events usually develop through winter and peak in spring, but this one is quite early which is less common.
Also, we generally (but not always) see positive IOD events coupling with El Niño’s and negative IOD events with La Nina’s. The correlation is strongest when the El Niño/Niña signals are strong, but they can exist independent of each other.
The correlation exists thanks to the warm water build up seen in the western Pacific during La Niña’s flowing through to Indonesia, favouring a negative IOD, and vice versa during El Niños.
Looking at the current state of play across the Indian Ocean, and following last year’s positive IOD event, the index only temporarily dipped to neutral during February before pushing back above the positive threshold (+0.4°C) into March, and persisting into the end of April at +0.68°C.
Long-range seasonal forecasts from nearly all meteorological agencies around the world are pointing to a positive IOD event developing over the coming months, peaking through July. As stated above, this is earlier than normal with it expected to start backing off through spring.
Chance of sea surface temperature being higher/lower than normal for June/July/August. Dark blue = 70-100% lower, dark red = 70-100% higher (ECMWF)
The impact to the Australian winter swell season looks neither here nor there, with there being no significant correlation between IOD events and significant wave height across the southwest of the country.
Looking further afield, and the stronger than normal trade-winds across the northern Indian Ocean should favour the Maldives and Sri Lanka, with plentiful amounts of southeast trade-swell likely through winter.
A quick scan of the East Coast reveals no major driving signals thanks to the slow transition between the outgoing El Niño and the likely La Niña during our winter surf season.
//CRAIG BROKENSHA
Comments
Mogadishu Somalia looking like nice warm water for a trip away with the kids... uncrowded for sure.
Free drag down the street naked and deceased too
Damn, it was cold in G-land in Oct.
Define your cold please.
I was cold in a long sleeve wetty top and boardies in September.
Tempted to take a short arm springy this year.
Always took Plenty of Rubber to Indo
But never Neoprene
Only Latex :-]]
Udo you sly old daawwwg. Down boy!!
Ha!
Concur...was there late October and it was the coldest I have ever been in the water there....old man feet and toe cramps after an hour or two...(boardies 2mm long sleeve vest), taking a chest zip springy this year.
I took a LS springy and still most sessions ended up cold and cramped- usually surfed long sessions.
It's often super cold there right? Must have to do with some local bathymetry and current stuff. Could easily do with a springy when I was there, would have upped my session times.
Yeah, the shelf comes in close there. It's a point of enhanced upwelling for sure. Seems to originate from there, westward.
Fcking freezing in the ments a few weeks earlier too.
Yeah was cold oct, nov, dec at times. Proper short arm springy/ short arm steamer chilly
I was freezing in a 2x2 short-arm steamer. My mate said to bring a 3/2, lucky I did. Was great for the other tourists who only lasted 15mins lol
amazing how cold it can get in indo especially out on the reefs in the wind
I get the same in Hawaii, trade winds ..........
I usually run either a wetsuit top
Or pending temp. A long arm short Leg wetty.
Great read as per usual Craig.
Noting stronger trades and cooler waters for Indo, what does the positive IDO mean for swell in Indo / Sumatra?
As per the comment for the southwest, there's no real correlation between the IOD and the swell patterns. So I can't offer any real insight sorry.
That's insight enough Criag - thanks
Nice one Craig. Back in the saddle meteorologically speaking.
Huge set on the head no problemo.
Heading to Maldives in a month so that sounds positive
Welcome back Craig, hope all is well with the family.
Unfortunately the mention of "the likely La Niña" brings fear to my heart. Cold Indo followed by shite home waves for months. Bah!
Great article!
Does the wind speed decline further to the east (Nusa Tengarra) or is it similar across the archipelago?
Generally yes, the strongest winds are generally seen from west Java through to Sumatra.
Oh no, water temp isn't an issue, but another year of southerly's suck and im there June-July
What's happens re southerly indo ?
I know you've spent plenty of time there also with out a fin key .
In Mentawai's & Telos normally the winds are a mix of direction's and ever changing allowing you to surf rights and lefts and helps it spread's out the crowds especially if very light wind, but when the southerly's kick in it sends everyone to limited protected spots mostly lefts which makes it much more crowded and you also dont get the opportunity to surf rights much and some rights like the one in pic really need an offshore on it to line up or no wind for a long time over wise even with no wind there is still a kind of southerly wobble in the swell.
gotcha indo,
figured it would either do what you said and or create a hell of a morning sickness issue.
spent a lot of time on islands.... which is great cause if they are small enough you can always drive to a side that is offshore.
ments has always been sold as this" Surfing Utopia " is it though? seem fickle sometimes.
like the print media would fib and only run the photo from the sunny good Great days... thanks for the response.
Nowdays people are becoming more open and honest about the ments.
I'm sure there will still be waves, it just seems so busy in indo nowdays....
still have a few spots on the bucket list.
Hmmm i wouldnt call the Mentawais fickle(apart from the far south area) and i still think it has the best most consistent waves in the world even in a year with bad winds every week there is waves breaking that are as good or better than the best day of the year at most peoples home break, its more that one of the best things about the area is not having a set wind pattern it keeps thing interesting and gives you lots of variety and spreads the crowd out and there are times when wind shifts happen and you can still get uncrowded waves if onto it even if for an hour, set southerly wind patterns kind of ruin all that.
But a year like this still favours certain waves like Macaronis which is close to offshore in a southerly and even if it swings more easterly its still just as good as when straight offshore, places like Thunders also love this wind or if a big swell hits Kandui left will be on fire, but there will be less good days at places like HT's or Riffles and if it goes tiny most of the swell magnets will be onshore. (apart from Thunders)
Same deal in the Telos the main spot im located at will be close to offshore and fun waves and even though the it will be more busy than a normal season, i will be able to pick window's to surf.
But yeah just less chance of surfing rights and as a natural footer l like to go right, at home i can go months without going left :D
Macas would be the most crowded wave on the planet next snapper. Packed even at 2 foot.
I ran the resort in 2008 but havent been back since it was manageable criwd wise then but heard it is much more crowded these days but footage ive seen isnt as crowded as many other waves...im happy to say i have surfed it pretty fun with just one other guy and had it with a handful of guys pretty good.
Your a very lucky man. They let one boat a day plus the resort crew (10 + whatever people). The day we booked it was flat however we went past another day (anyone can surf it before 9am) and it was chockers at 2 foot. Looks a great wave however like every place now very crowded. The Mentawis are really at bursting point you can still luck out if there is some swell but if it just ocean background swell the few exposed spots get ridiculously crowded and lullish. Remember every boat has 10 people and there are dozens of boats plus a plethora of land camps - it is packed. I am scratching my head why the Brazos spend all their money getting there when they have Mexico on their door step.
I was there in 2014 & it was a joke. Rammed at 2 foot. 3 boats & all the resort guests. Plenty of other places to surf in Indo.
What does this mean for the south West winter ?
Looks like a typical winter for your region. Though the frontal activity might be more focussed just west of the region, bringing fronts with a more west-northwest wind bias.
Will it have any bearing on the Maldives come September?
Hopefully in a good way?
Does it ever get cold there in and out of the water?
Excuse the multiple questions but I'm what's known in layman's terms as lazy.
PS- Hope all is well with Mum, bub and your good self.
In my experienced the Maldives never get cold, you actually want it to cool down at times!
And yes it should be favourable still into September.
Yew!
Arigato Kureigu san.
Would this have any implications for South Africa?
What about that cyclone that’s hovering around south of indo in the Indian Ocean? Seems very late and a long way south
Another great article.
Hi Craig
Would you say because it has come on so early it will gone or backed off before late season ?
I am of to the ments in October and didn't think this would be an issue because it was so strong last season
It's too hard to be certain this early, but current outlooks have it fading into the late season and going towards neutral. There's a lot to play out between now and then.
Thanks Craig
Fingers crossed
No doubt you will keep us updated as the season goes on
Then we have channel 9 Brisbane weather man telling us warm water in May was “good news” , despite an earlier segment saying how the warmer ocean temperatures were killing the Great Barrier Reef!
“Rubber up”!
“extra” rubber!
Bali!
Talk about digging around for an angle.
So what will the water temperature be? 27? Or maybe even 26? Degrees C not F. WTF?
19-20 when I was last in G'land and an upwelling occurred. The only crew who could put in long hours were those with springsuits or the old guys wearing steamers.
What was Temp for you last year Freeride ? Blindboy had 17C one Year
I reckon 20-21- was colder up the Kongs end of the reef.
Watching first timers jump out of boat in cold deep water expecting Ulu temps is the best.
Why are there still sou east winds blowing almost every day through April and now may, on the south aust coastlines ????
On another note:
Gardening zucchinis still and that's about 6 weeks later than I've ever seen before !! Climate change!
Its taken the last month of warm weather to happen, they are slowly growing, it's not like they do in summer but still pretty good specimens so there thats my contribution
Craig, from a water temperature and strong wind point of view, is it safe to assume less of an impact as you venture north of the equator in Sumatra - e.g Nias, Banyaks & Simeulue?
Unfortunately not, the wind signal extends right up the Sumatran coast under strong events.
Check the arrows here, this was the 2019 record event.
Winds were strongest in the Ments, a bit weaker north.
Interesting Craig, thanks for making comment.
Lets hope it breaks down sooner rather than later.
What's with the sou east winds, being predominant now in April May
Java has cooled off..
Here's the cooling trend for the last week, has dropped 2-3°C off West Java.
Yeah its time, 1 palm Pt, wear a thick wetsuit
In positive news for those heading to selected locations, it looks like the developing + IOD has stalled and it might just stay more neutral through the coming season.
The reason..
A developing MJO signal in the Indian Ocean/Maritime Continent, bringing west winds (red/brown shading), killing off the south-east winds.
Also note the dark blue/purple which is stronger than normal easterly trade-winds in the Pacific, helping to promote upwelling and the transition towards La Niña.
We'll continue to monitor things and I'll have a fresh article this week on both ocean basins.
Awesome, yeah ive been watching the winds in offshore Sumatran Island's and yeah they have been very variable and quite a few NW definitely no set southerly pattern.
@indo , nearly everyday the wind went around in circles, clockwise some days anti - clockwise others, nearly always started out offshore and finished offshore, very few onshore all day days . ESE was offshore where I was . Water wasn’t as warm as a few years ago which was a relief .
I'm lucky to have just come back from 2 trips - G'land & NW WA - the former way colder than the latter. Still only boardies and rashie in the G (noting that Craig's analysis says cold coming later in the year.). Conversely, NW WA has never been so warm, ever - in my experience. Only wore a steamer once, 1st surf, then bagged for short arm springy or thin wetsuit vest & boardies thereafter. Couldn't help but think about the permanency of climate change whilst in NW WA.
Yes RR, NW WA can't remember it being so warm, and green
how were the crowds in the NW mate? Settling down from COVID times?
Quieter than the year they shut the WA border, that was firking manic but busy busy busy never to return to pre-covid era (that applies everywhere I think)
@seaslug: yeah ok. One of the best surf trips I've ever done. By going on what people have told me of the past couple of years, don't think I'd like it as much now. Still a very special place. Seems like they've had a good run this winter.
Hey solitude > I concur with seaslug, the 2020 & 2021 years were shocking up there with crowds, but it seems to have settled down a little since..perhaps 'coz indo's been off its nut for months!! so I'm going back up there in September...> RR
Wow, thanks for the feedback RR. That's worrying.
yeah Craig; sure is? I don't have the scientific capability of your brain but very interested in charting our combined future. On a purely selfish front, I'm doing last season indo this year as well as my normal early season, partly due to your projections. I will update with experience, if that's still an interesting topic for you.
Yep. Always is RR! Keep the updates and feedback coming.
Hi Craig
Any updates on late season outlook for ments ?
I'm headed there on a boat trip in the first couple of weeks in October
They have been having great swell lately just wondering how long it will carry on for
Thanks in advance
It's a bit far out for now, but the S/SE winds have been hammering the southern locations. Looks like the positive IOD signal came through.