December Climate Update Webinar Video Transcript
Date: 9TH DECEMBER 2010PRESENTER:
Thank you very much. Here we go.
Looking at November's summary from the Bureau of Meteorology data, you can see, first of all, this is a map of Australia showing the decile rainfall. And, you can clearly see the - - you know, the large amounts of rainfall through the eastern half of Australia, and a few patches of dryness sort of over in WA still and some bits of wetness here off Exmouth, Port Hedland. But, so, most of the action was in the eastern parts of Australia this month.
You can still see on the level of greenness as taken by the satellites on the MDVI there's still a large, vast amount of greenness, in the interior of Australia, which is quite abnormal to normal. This is the amount of greenness compared to normal, so he you still see southern Queensland quite green, and now Victoria returning to, you know, slightly normal for greenness. There's a lot of stuff really that did start to dry off before the rain kind of started.
Looking at temperatures, these are maximum temperatures here. You can see there's a large minimum in Queensland. There's a sort of a maximum anomaly going over here on the coast of WA, but Victoria, apart from the Gippsland coast, which was sort of 1 to 2 degrees above normal, most areas of Victoria were either close on average or just sort of slightly below average.
What people might not have realised of course, because we're normally asleep, is that last month the minimum temperatures were sort of 1 to 2 degrees warmer over much of the state, and this can often happen. Plants and animals notice what's going on, but humans tend not to unless they're used to getting up very early. But, slightly warmer minimums and close on average maximums, which many people would probably find quite surprising.
Now, I've got the right arrow here - - here we go. So, now we're just moving on to the sea surface temperature charts. This will be a little bit different to normal. What this one I'm going to show started in January this year. And, if you've never seen any of these charts before, this is the temperature of the ocean as taken by satellites and all sorts of probes and floating buoys around the world put together to give you the absolute temperature, and then you compare that to what the temperature should be for this time of the year.
So, what we're looking at is the sea surface temperature anomaly chart, which is the differences for normal, and the yellows, oranges and reds are where it's warmer than normal, and the blues and purples are where it's cooler than normal.
The area to look at in this chart, first along the equatorial Pacific Ocean here where we'll be looking for the evidence of Al Nino and La Nina. Off the island of Sumatra and off the coast of Africa here at Kenya, looking for the occurrence of the Indian Ocean dipole, and apart from that, just the general warmth of the ocean to the north of Australia where most of the moisture sources from rain come down to us, come from, and so we're just looking in that general area as well.
So, we're starting off at the start of January, and as you can see in the field here, that is - - if you've never seen an El Nino, that's exactly what it is. The slight warming above 0.8 degrees of the ocean along the equator. We had one of those in January, and that was in the process of breaking down.
Moving on to February, not much changes there. A little bit cooler to the north of Australia. March, you can see the equatorial Pacific here sort of starting to cool down. April, still sort of cooling down here, but still a little bit of residual warmth, and by the time we get to May, that Al Nino had pretty much broken down. The ocean was still slightly warmer to the north of Australia, but pretty close to normal. The Pacific Ocean was - - the Indian Ocean, was pretty much warmer across that gradient through the equator. And, as we move into June, we just had the very faintest sniff of La Nina becoming visible at the surface, a little bit of this sort of eddy current formation here through the equatorial Pacific.
As we get into July, there was little bit more of that building up; into August. By August, we actually did have a La Nina by definition as the ocean in much of the parts through this sort of box here, was below 0.8 degrees cooler than normal, so below -0.8 degrees and so the right trend was showing there for the season coming up in terms of rainfall and the La Nina looked like it was establishing itself. And we just did start to see the right sniff of a trend of an Indian Ocean dipole negative here, with warm water being in Sumatra and for slightly cooler water just starting off the Kenyan coast, which we hadn't seen for many, many years.
Come September, well, that La Nina had intensified some more. You can really start to see the amount of moisture to the north of Australia - not so much the moisture but the temperature of the ocean picking up, and particularly through the maritime continent of Indonesia, and we did have a week IOD negative had formed, slightly cooler here off Kenya, and warmer off Sumatra, and that provides a flow of moisture moving in, with prevailing westerly wind patterns moving moisture into the tropical areas north-west of Australia providing a moisture source.
Now, this is pretty exciting, because we hadn't had one of these for 18 years, and the combination of a La Nina and an IOD negative, you've got to go back a fair way, in fact, back to 1975 where we had the best attempt of those two combinations coming in together. So, clearly we were breaking new territory from what we had for the last lot of 10 or 15 or so years, but which was quite exciting.
Moving into October, you can see that IOD negative now sort of it's still just quite a weak one, but it was nonetheless reasonably helpful, and here the La Nina still going ahead, and the moisture to the north of Australia intensifying.
November, the IOD negative had basically broken down through October, which is as it usually does. It's usually a thing that only happens through winter and spring, and it breaks down, so this is quite a short lived event. It really only occurred through September and October, and by November she was all over. But, you can still see that there's large amounts of warm ocean to the north of Australia and we've still got our La Nina.
So, this is looking at the very most latest sea surface temperature chart for a couple of days ago, and in the Pacific Ocean, we look at three separate areas, and you will often hear them termed Nino 3 in this pink box, Nino 3.4 in the green box, and Nino 4 in the purple box, and they're just describing a box of those in the Pacific Ocean. And, as of a couple of days ago, the temperature in Nino 3 was -1.3 below zero. The green box is -1.38 in Nino 3.4, and -1.22 degrees below zero in the Nino 4 region. All of those areas of Pacific Ocean are below the figure of -0.8, so they're well above La Nina at the moment.
Out here in the Indian Ocean, Sumatra and off Kenya, the dipole load index measurement of the IOD is at +0.07, which is very close to 0 and is essentially neutral, and as you can see, there's very little difference in the gradient of temperature across there in the Indian Ocean at the moment.
All the seas to the north of Australia are very warm, but there's still - - there's one very particularly warm stretch here in the Indian Ocean to the north-west of Australia, and still particularly through the Arafura and Timor seas and in the Coral Sea, which are major moisture sources for us at the moment, and every raindrop that fell yesterday was pretty much coming from those tropical areas.
So, looking here at just a change in the sea surface temperature for the month, looking at November minus October, anywhere that's blue has cooled down. Anywhere that's red has warmed up. In the Pacific Ocean here you can see that there's very little that's warmed up. You can see a couple of small spots here that have warmed up through the equator, but not much. You can see a very large area here north of New Zealand and up to Fiji, which has cooled down. There's this big warm spot here off Port Hedland and Exmouth. You can see that the area here off Kenya warmed up, and the area off Sumatra has cooled down, which was what nullified that IOD negative. But, really, not much has changed to the tropical areas north of Australia.
Looking at the undersea now, and this tells a really interesting story when you look at it through the whole year. So, this is taken by the permanently moored buoys through the equator, the Tao/Triton array, which every day drop to the bottom of the ocean and come back to the top and give as temperatures soundings and salinity readings. And, they draw off maps like this where you have Papua New Guinea here in the west, Ecuador over here to the east, and to about sort of 400 metres deep, and once again you're looking at sea surface – not sea surface, but sea temperature anomaly to depth. Anywhere that's red, it's warmer than normal. Anywhere that's blue, it's cooler than normal. And you can see that some of these sections in here are sort of up to 3 and 4 degrees warmer than normal here in January which was when we had our El Nino, and you can see that El Nino going through February, March, and April, starting to sort of disappear in the amount of heat that was actually underneath the ocean. And, this is really what drives a lot of these things. I kind of consider this undersea stuff a bit like the thermostat on your gas cooker. But, what you can see here was a large amount of cool water starting to form, starting to move underneath, and starting to take out some of that warmth in the heat here which in turn comes out of the surface and drives the heating of the surface.
So, here you could really see the thermostat being turned down really by that cool undersea, and you can see the erosion of the El Nino up until April.
Then, if you look into subsequent months, May, June, July, August, you see a very rapid increase in the amount of cool water to depth, and so this is what gave everyone the confidence that a La Nina was at least possible, and that it might be hanging around for a fair while. And you can see you know, in terms of the thermostat, you can see that the icebox had really been turned off underneath the Pacific Ocean - - or turned on, sorry, the icebox, cooling that ocean down at depth, which helps to really start to cool the ocean at the surface, particularly as some of this cool water comes up in the east, gets blown across by the trade winds and starts to propagate that cooler water towards the west, and creates that tongue of cool water through the equator.
So, when we got to August, that was when the threshold at the surface was reached, and you can see that we did have a massive slug of quite cool water underneath for quite a distance.
Moving on to now, August, September, October, November, that cool water has remained at the surface. It still remains four degrees cooler than normal. We still have that tongue of cool water through the equator, and what's interesting compared to time - - normal time, is that you usually see a propagation of this warm water moving back underneath the thermaclyne in this direction, which is where the thermostat has been turned up, and you'd start to erode some of this coolness here and you know your La Nina would start to disappear. And, then, over the subsequent months, we've seen no evidence of that happening. In fact, many of the models are predicting that that La Nina is going to incur down to May. And, why are they predicting that? Well, in part, it's because they can't see this large amount of cool water underneath here which is driving the system disappearing all that rapidly. In my experience of looking at this undersea stuff, that's true. You don't see a large amount of cool water four degrees cooler suddenly go to neutral in the space of a month. That simply just doesn't happen. So, it's going to be a slow progress of decreasing this coolness or in fact, it may not decrease at all.
Looking at one of the other factors of climate and particularly El Nino and La Nina through the Pacific, is the position of a lack of cloud around the international dateline at this position here. This is a map of cloud or outgoing longwave radiation taken by the satellites. Anywhere it's brown or yellow there's less cloud than normal for the last 30 days. Anywhere it's purple and blue, there's been more cloud, and for a La Nina we would expect to see a lack of cloud around the international dateline, as you can clearly see here, but really that tongue has extended right over to the north of Papua New Guinea as well.
What you do see, though, is in Australia, this very large amount of cloud that we've experienced for the last month troughing down, troughing down from the tropics all in the eastern areas.
And, for this time, for a very, very long time, for as many months as I can remember, perhaps four or five months, there was a normal amount of cloud throughout Indonesia, whereas that's really been a hot bed of a large amount of tropical cloud for a very, very long period of time.
In terms of the historic context of this through the whole year, that cloud over the dateline decreased through May, and by mid July, we had a classic - - a lack amount of cloud at the dateline, which was indicating that that La Nina was really hooking in, and it was decreasing the amount of convection of - - because as you remember, there's a cool tongue of cool water coming through the equator, and that's going to be evaporating less moisture by being a couple of degrees cooler and therefore there's less cloud formed above that ocean, which is where this graphic here comes from.
The other thing, of course, that happens in La Nina is that the trade winds totally changed around. This bottom map here is a picture of the trade winds as taken by little direction finders on tops of all those buoys that are situated all through the equator and north and south of the equator, and they're giving us daily and hourly loggings of things in fact. Anywhere you see an arrow on this chart, the wind is going in that direction much stronger than normal, so if the trade winds were behaving normally, perhaps as you sort of see in some of these areas around the Pacific there are no arrows. But, you can clearly see, that the western part of the Pacific, the trade winds are blowing way stronger than normal.
Why is this important? It's because the Walker circulation that causes this phenomena to happen, and that pushes the cold water further over in this direction, and that - - by in turn doing that, it pushes the warm water pool, which is normally sitting out here, pushes it to the north of Australia and through Indonesia and Papua New Guinea, which is where some of that warm water is coming from at the moment, which is normally sitting out here. La Nina pushes it to the north of Australia, which allows it to be a moisture source for our rain, and that's really the fundamental difference I think as to why La Nina has the potential to make things wetter in Australia by moving that warm pool of water to the north of us.
In 2010 earlier on, we had a lot of westerly anomalies where these arrows were in fact pointing in the opposite direction, and we actually had reversals of the trade winds, which is really classic in El Nino, which is happening during summer, and those westerly wind bursts helped to prevent - - they keep the ocean warm, keep the El Nino going, and help to prevent La Nina sort of forming. But, eventually those westerly wind bursts disappeared and we started to get some easterly ones, wind bursts happening and strengthening, which helped to really wipe out that El Nino, and the easterly trade winds started strengthening in late June as the Walker circulation started to pick up.
And, the Walker circulation is measured by our good old friend the Southern Oscillation Index. And, you can see here that for the moment he's still strongly positive here. It's sort of +17. Any value above +10 is fairly significant as being indicative of La Nina. You can see since July of this year, there was a rapid rise into the positive and it stayed up into - - these are quite - - very high levels of the SOI here at sort of +25 - - sort of not quite record-breaking but almost, and so you can see for all of this winter or late winter, spring period, there's been a very strong Southern Oscillation Index, and that really is just measuring the strength of the Walker circulation, which is telling us that the position of the clouds throughout the equator and the strength of those trade winds are behaving as you would expect for a La Nina. Whereas, you can see here throughout parts of last year, throughout July sort of - - actually from 2009 here we had an El Nino kicking quite late in September/October, with some strongly negative sort of tendencies, and it drops quite negative over summer, and then it changed its mind and it slipped right up here and we had suddenly seen that. We saw the change in the SOI change before the ocean and the winds and the cloud sort of happens. So this sort of was really the predating for some of that sort of stuff changing over because of La Nina needed to happen.
So, at the moment the ocean and the atmosphere are what we call fully coupled. Everything is working in beautiful harmony, which if you weren't wanting large amounts of rain during summer, would be a good thing I suppose.
Looking at perhaps a different index than you might have seen here, this is the Dipole Mode Index, which measures the difference in temperature between Sumatra and Kenya, and you can see here that the IOD, for the last sort of three to four years, it spent most of its time above zero, and we've had a number of IOD positive events in those times, and that's when there's a lack of moisture happening off Sumatra. The wind flow is in the wrong direction and there's a lack of flow of moisture coming into the north-west of Australia.
You can see here, though, through that month of September that it's got below the -0.5 threshold, and we actually did have some IOD negative activity happening there for a couple of months. You can see that it's just climbed back up again and the IOD negative has happened. And, this is quite typical. The IOD really only often happens in the sort of three, four month, two-month periods, whereas what happens in the Pacific Ocean is clearly - - is more in the sort of 3 to sort of 8 month periods. It's a much more long-term event.
Looking at air pressure now changing to something more sort of synoptic around the area, this is just November's air pressure here. We usually talk about the position of the subtropical ridges where the centres of the high pressures are centred over Australia. These are some of the things that have been killing us over the last sort of 20 years where you see the positions of these highs too far south for the time of the year.
This year, essentially the subtropical ridges played ball most of the time. In winter it was situated around the Bight. In summer it was down around here around Melbourne, and at the moment it's in the progress of travelling from the Bight back down to Melbourne and you can clearly see through November that that in fact was the case. So, fortunately position of the subtropical ridge has been playing ball this year for us.
But, what hasn't been playing ball is the actual pressure, and so the pressure that we've experienced over Australia, increasingly of course that's a long-term trend that has been happening over many, many years. You can see here, this is a similar chart to before but it just shows a bit more scope, and you can really see this large blacking - - blocking high out here for the month in between New Zealand and Australia, a large high off the coast of WA. This is sort of a permanent high out here. It's either close to WA, or moves back out into the Indian Ocean more, and it really does regulate what happens on the south-west coast.
But, for Victoria you can see that we were really between two areas of high pressure for the whole month, and there was a constant troughing or the ability of moisture to trough on the back of these northerly winds on the back of this high moisture, because it was up there coming down here.
And, it's very interesting to contrast this with a year ago in the first two weeks of November where we had a massive fry-up, and the real difference is only that that high was 500 kilometres or more positioned closer to Australia. There were stronger northerly winds coming down here, and last year we had El Nino conditions, and there was a lack of tropical moisture up in this area. So in November, we had very strong, hot winds, coming down, and this year because that high is just a little bit further out this way, those winds have been weaker and the large amounts of tropical moisture and the lower pressure at Darwin has allowed that troughing moisture to come down and keep up the big wet that sort of seems to have no end at the moment.
Of course, dairy farmers in the North Land area of New Zealand were absolutely hating this. It's always the case with the weather, it's someone's win and someone else's gain or loss, and there's no difference here that the northern parts of New Zealand have been experiencing quite a typical drought that some farmers haven't seen for a very long period of time, or not at all, so they're talking about drought been declared in those areas over there at the moment.
Let's look to a totally different phenomena now. This is the Southern Annual Amode. This is the Antarctic oscillation, and it's a measure of the pressure and the winds and the westerly winds in particular, that are blowing around Antarctica, and those winds either strengthen or weaken, and when they strengthen it sends up a circumpolar vortex and the low pressures and the storm fronts and the cold fronts get dragged in towards Antarctica, and they get sucked away from southern Australia when the Southern Annual Amode is in its positive phase.
When the Southern Annual Amode is in its negative phase, those winds decrease and it allows the storm tracks and the low pressures storms to blow up closer to Australia, and particularly affects the southern areas of Victoria, particularly over winter. It's very much more of a winter phenomena.
This is just a graphic here of the Southern Annual Amode over the start of this sort of season, and you can see for large amounts of the time the Southern Annual Amode was very, very positive, which is a long-term trend now that's been set up sort of over 50 years. Last year, we had a negative Southern Annual Amode and you are right if living in southern areas, there was very frequent frontal rain and even when you were north of the Divide last year, there was sort of rain, but not much, sort of every one or two weeks.
This year's been interesting in that the rainfall has been quite high. The Southern Annual Amode, has been quite positive, and it's really because a lot of that rain has come from the tropics. It's been set up by low pressure systems that have formed over Australia, cut off lows, and it really didn't have much to do with frontal systems coming through. The southern parts of Victoria got frequent frontal rain, and the Southern Annual Amode was sort of just clipping them, but because the Southern Annual Amode is a very raw sort of index, and it's really taking things around the whole of Antarctica, they're really is no measurement for some of the sort of local effects that might be going on.
The drought in Western Australia has been blamed a lot on the absence of the Southern Annual Amode and absolutely no frontal activity coming through that south-western area of WA. Interestingly enough, South Africa was in drought conditions this year as well. Being a similar latitude, the Southern Annual Amode, would be expected to affect them, too.
Eastern Gippsland is the only part of Victoria that is showing dryness at the moment, and you would expect that too, with an absence of fronts not being far enough, high enough north, so that they can go across the divide and come through and still be there once they get to Gippsland, whereas when those fronts have been dragged southwards, by the time they get to Melbourne they skip through sort of Warragul and East Gippsland, and West Gippsland is just in the rain shadow as usual. But, certainly they've been experiencing a lot of that this year. And, a lot of the tropical rain that's come from the north from those lows, well, once again the divide still puts them in the rain shadow. So, they really need a Southern Annual Amode to return to some normality to help them there, I suspect, although the Southern Annual Amode really has no effect - - or has an effect for them over summer. It has no effect over us for summer for most parts of Victoria.
I will go on to my next slide here. This shows the Southern Annual Amode currently, and you can still see that bar a little bit of a dip into the negative during late September, it's still up in the positive at the moment, not that we'd expect frontal activity to be strongly experienced over Victoria at the moment.
The one thing that can happen, though, is that when the Southern Annual Amode is in its more positive phase over summer, East Gippsland can get more prevailing easterly flow coming in on their side and so the potential for a bit more summer rain in East Gippsland potentially if that Southern Annual Amode does stay a bit more positive. At the moment the 7, 10 and 14 day forecasts are predicting a slow return to 0.
As you can see there, the Southern Annual Amode is something that changes in the space of weeks or fortnights, so it's not something that has a long and varied predictability. You can't sort of predict very long out at all. In fact, 7 to 10 days is about all we've got at the moment that's remotely accurate, and once you get out to about 14, you may as well be slipping into corners, as anything is possible.
I usually show this. This is NOAA in America, just a map of their storm tracks for Australia. Anywhere you see a wiggle, there's been a low pressure system. Anywhere you see a red dot, there is a low pressure system. This red dot, because of the age of this graph, was the one that just went through us yesterday. You can see the tropical moisture all down through the east. But, you can really see that through the month of November we did have a low form over Melbourne and drift off out here into the Tasman, but there really was no real low storm pressure activity coming from higher up, and coming down through Victoria through the month of November.
As I said, we had a number of cut off lows which did form this year, which are really the events that bring the most rain to parts of northern Victoria in particular, where a low pressure gets cut off from the streams that are normally heading in this direction, and gets pushed up a bit. But, it gets cut off. A blocking high might sit out here in the Tasman, and that low then moves very slowly across Victoria, and gives us those sort of you know, one and two day rainfall events, the sort of things that many of us can remember if we were old enough, happening when we were young.
Talking - - turning to another tropical phenomena now, the Madden-Julian Oscillation, which is the 40 day wave that sort of comes off the coast of Kenya here and travels across and finishes sort of out off Fiji in a 40 day sort of pattern often.
When the MJO is in a position five, it's really a massive cloud that you're measuring in the Madden-Julian Oscillation that moves across here, sort of counter to the tradewinds, and when it sits in position five there's a tropical air mass up there that's moist that has there be ability if you get the right triggers coming through Victoria to drag moisture down.
So, this chart is what they call a spider diagram. Africa is here, and Fiji is here at 8, and the MJO should normally travel around in a circle like this. You can see following this line that green was November starting with the red, and it sort of moved around. It's doing nothing much at all, except in the last couple of days, it's actually moved out into position 4. The models, most of them are predicted to enhance and to come out into position 5, and hopefully that will - - well, that might have actually led to some of that moisture coming through. I think this graphic is a little bit older. Clearly we are at day 9 now and that's sort of out here. Well, clearly some of that moisture yesterday could have come through from some of that MJO event. But the MJO is quite hit and miss. It sometimes starts off the seasonal break. It's more associated with the monsoon events that happen in the north of Australia. But, any time you get one and you get the right triggers coming through, you can get sort of things working in harmony there to drag stuff from the north. This year, we did have some brief moments of glory in April, August and October.
Moving on here, so, I've got a couple of questions here which I might be having a bit of a look at. There was a question here about the IOD. look, the IOD reason is an interesting thing, and it would depend on who you talk to as to whether some people actually believe it's a real phenomena or not, and I think there's something clearly in the IOD. However, I do - - I'm with a few people as well who more believe that it is really more to do with that warm ocean to the north of Australia, irrespective of what might be causing that. It's just that the IOD negative and the La Nina are the two very major events that really do help to warm that ocean up to the north of Australia.
You've got to remember that the IOD negative is really a measure of Sumatra and Kenya, and Sumatra is actually a long way from north-western Australia, so you can get an IOD negative happening and maybe not necessarily have warm ocean around Timor, around there, but this year we had the warm ocean, but it really didn't get very strongly warm off Sumatra until really quite late and never – the long-term trend is for the Kenyan coast but it never played ball. So, we haven't seen really cold temperatures off the Kenyan coast during winter, spring now, or since I really looked at seasurface temperature records. So, really to couple up, I think we're really looking to that Kenyan area to start playing ball.
Now we're looking at model performance. A few disclaimers. This is my dodgy non statistical view, where I've gone and looked in the predictions in the fasteners provided by the Fast Break, and then gone back and looked at the decile maps of rainfall that fell over Victoria, and just compared them to see how they went.
Now, this is by far going to be the worst graphic of the day. We have a number of different models that appear. Hopefully most people get the Fast Break. If they don't they probably don't know what's I'm talking about. But, it's something that's put out once a month by myself of a number of different coupled computer models around the world which are everything from this way to the left, and then we have a number of statistical systems here. So, these ones here are working on large computer programs that are modelling physics of ocean and atmosphere above it and model the weather over a long scale, sort of six month periods plus. And, these things here are just statistical things that look at what are we seeing in the ocean and the S0I and other things around us at the moment, and how does that compare to what's happened in the past when we've seen those phenomena.
So, here we have the month of the year when this is the month of the year that the prediction was made, and this is the three-month period after it. So we're looking at the short-term performance here of models predicting from 1 to 3 months out from the month before they were making the prediction.
Where you see orange is where someone has been partly correct, so they've got parts of Victoria right but they've bombed out on some others. Where it's red is where they've majoritorily got it wrong for Victoria and where it's green is where the majority is they've pretty much nailed it and got, you know, pretty much the whole state right for the month or for that three-month period.
So, you can see here from any of these models, you can see some sort of pretty well poor to average performance through most of February, March, April, May, which is that sort of prediction window where things don't really happen, things are changing over in terms of the Pacific Ocean and that and it's that predictability barrier which most models and most climatologists really struggle with at this time of the year, and these models are generally no different to that.
You can see a couple of models here getting - - sitting on the fence and giving some average rainfall predictions, and actually managing to come through for some of these periods. What you do see, though, is a lot of these models once they get to July and August and there was that sniff of a La Nina happening, that many of these models have had very excellent performance in fact, of predicting weather conditions back in July and August for our spring.
The one that you don't see performing so well is the BoM seasonal forecast here, which over the last couple of months has gone for really average conditions over Victoria, and that's not surprising given that La Nina on average doesn't actually give us, you know, increased rainfall on average. It does give us rainfall on average about 50 percent of the time, but 50 percent of the time it could be average or below, and this is the problem with a statistical system I suppose, is that once we had a La Nina that was suggesting that the odds for Victoria were pretty much average, whereas all these computer models had seen that there was something very different about this La Nina. It was quite strong, and the way it was going to set up was most likely going to give weather conditions to Australia, and that in fact has certainly turned out to be true.
Let's look at the real navelgazing now. This is the six-month prediction, so people making a prediction sort of four months' out for 4 to 6 months. And so, once again there's only the main - - the big computer models are the only things that have the ability to do this, and we can see here the month of the year once again and the months that they were predicting sort of four months out.
Now, what you see here is some interesting performance here from a number of these models getting things pretty right in April for spring, which is sort of three months earlier than a lot of those models where they all start to get it right. But, you can also see that by May a lot of these computer models are actually predicting the spring pretty right, which is I think a reasonably exciting thing. A lot of these models this year managed to get things right, and whether that's through just sheer luck is a possibility, but clearly, they were on to that La Nina building up and happening and thinking that it was going to be a significant one to provide rainfall.
Of course, not every model has got it right. This one here, the US model, here the ECPC, has really just out sat on the fence with average and you know managed not to jag it at all. But you can see that none of these models really had a very good chance of predicting anything going on through January, February, March for spring, because once again, that's where the period of most uncertainty is, and we're sort of coming into that period now.
So, this is some of my summary here. Some of these models, the European Centre model, the SINTEX, the Japanese model which you will often see written up in the Weekly Times. The NZ model, which is one of my favourites, got the timing of La Nina pretty right in March, some five months' out. The UK MET office model was one that joined them in May sort of three months out from the end, which I think is quite an exciting performance there. You're only as good as your last forecast, so a lot of these models will be hanging their hat on I think getting this right.
Many models, however, lit their powder a bit early, thinking the La Nina was going to kick into place in May or June, and as I showed, it didn't really lock until August. In our own POAMA model here put by the Bureau, the IRI America and ESS, which is the David Stephens Western Australian Department of Ag model, they hold off and they got the short-term timing of the La Nina right, thinking that it wasn't going to lock in until it actually did.
Interestingly enough, the European Centre and the Japanese model here and here, they predicted the weak IOD out in March, some five months out, but then they kind of hopped off it, so they were on it early but then they got off the horse and so it was a bit of a sniff of it around, but they weren't overly convinced themselves.
By June, all the models were predicting warm Indian Ocean temperatures near Australia, but most were never, ever, convinced about an IOD negative of any sort of strength happening, which probably really kind of happened. There wasn't - - as I said, it wasn't a very strong event, and it didn't really happen much, and depending on who you speak to, some people might suggest that a two-month IOD negative event is just not strong enough to even consider that it's actually happening, needing to see sort of three months of continuous activity before they would sort of count it as an event.
The very last thing, Chris, I'm just doing the final model runs. These are the model runs that we do every month. They're ones I've just done a couple of days ago, looking forward for the next three months. Once again, looking at a number of models here so most of these models here are predicting the La Nina to stay hanging around as cool in that sort of La Nina fashion for the next three months. The Indian Ocean, pretty much sitting as neutral. There's a few sort of slipping slightly warmer, slightly cool.
What is interesting is the absolute consensus of these models for summer rainfall that the next three months, is going to be wetter, slightly wetter to wetter and wetter, and I don't think I've ever seen anything like that before in model consensus. It will probably just be average, but we are certainly in an above average December which is probably going to skew the average anyway. So anything like a sort of average January and February, is probably going to bring these models true to task.
Temperature is where it's a bit interesting at the moment. It's quite mixed. There's a number of average and neutral sort of temperatures and slightly warmers and a few slightly coolers. The models have really struggled with temperature this year. Most of them have thought it's going to be slightly warmer and yet Victoria has consistently been about average for most of the year, whereas most of the warming effect has been in northern Australia where it's been some three or four degrees warmer than normal.
Just moving on I think to my last graph here, which is the 4 to 6 months outlook for these models. You can see that bar none, all of them are thinking La Nina is around until the end of - - this is the March, April, May period here, until the end of may. The Indian Ocean is sort of predicted to sort of maybe cool off a bit, neutral to slightly cool. The autumn rainfall, you know, being in that predictability barrier, a lot of them are starting to go for safety around average and neutral, although there's a few more thinking that wetter is a possibility, and temperature once again is totally mixed, but as I said that 4 to 6 months out at this time of the year is absolute crystal ball gazing.Anyway, that's all, folks. Thank you for listening.