The BoM 3 month forecast Outlooks improved for three months after Spring 2010 but have deteriorated again over the last two months.
Below I have six panels showing Outlook forecast map alongside realworld results map for rain and max & min temperatures.
Outlook period January to March 2011
Rainfall
The Outlook has a western and eastern rain peak with a dry trough in between. In real life there was no sign of that – in fact the eastern area included some dry areas and there was no sign of the predicted large dry patch near Haddon Corner. IMHO this result would score under 50%.
Maximum Temperature
The huge hot patch predicted over the SE failed to happen.
The large predicted cool patch over WA was at best a 50% success. Overall I doubt it could score 50%.
Minimum Temperature
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Outlook period February to April 2011
Rainfall
The huge dry prediction over the SE never happened except for the small area in NE NSW. The SW WA dry patch was not predicted. It might score a 50%.
Maximum Temperature
It is clear enough no great success. Where they predicted notably hot in the SE, it was cool and in WA where it was warm, they had predicted cool. I doubt a score could top 50%.
Minimum Temperature
The huge cool anomaly predicted never happened – WA was a partial success but the SE and Cape York warm predictions failed to be anything other than near average.
Conclusion
Thinking of the entire group – are these expensive productions worth anything to the nation ?
Please check the label on the 2nd of the last pair of charts.
Thank you for these comparisons. Enlightening.
Added by WSH – Fixed that BH – thanks.
These computer models try to get it right for a three month forecast. Are we to believe that they can tell us what will happen in 50 years with global warming? What an expensive and wasteful farce. The BoM couldn’t have got it more wrong.
Isn’t it time for a rethink on the models used. I notice some crop forecast are also quite inaccurate and suspect the BOM weather forecast is a source for crop forecasting models. If nothing else the forecast anomalies should be writ large so that the unreliability of these forecasts are widely known.
Added by WSH – I have been trying to spread the word for years. Andrew Bolt is the only main stream journalist who speaks about the useless Outlooks.
How long before they drop that uselessly biased warming model?
Added by WSH – They have been using it for years Jack. Sections of the BoM are heavily influenced by mythology – I noticed that when I first met their people in 1991.
Warwick,
Looking at the test results, I think that you are being very generous giving them 50% for those outcomes. Unless of course you are using the schoolroom scale (of my youth anyhow) when a fail was given 50%. Certainly their performance deserves FAIL.
BoM,
“Probability outlooks should not be used as if they were categorical forecasts”
The problem, AS is, that’s exactly what the IPCC does. Uses Probability Forecasts (from a computer generated model) to ‘categorically’ predict runaway catastrophic global warming. If one is to put forward a mathematical model to represent the ‘best’ of the science then it must be tested/verified against empirical ‘observed’ evidence. The BOM, IPCC, CSIRO models all fail this important scientific requisite.
Looks like AS, the AGW troll from Bolt’s site, has made it here.
If probability forecasts were any good, over time, they should show some skill. They don’t.
The whole meteorological industry in the West has clearly been infiltrated by and is now dominated by green activists who care more about achieving a political end than practicing science. Defunding the industry is probably the best solution to this problem, as privatisation would inject some competition and the most competent outfit would emerge over time and would then be somewhat useful. As for these current knuckleheads, did they think we wouldn’t notice their continual manipulation of the data to suit their political leanings? Their stupidity really is breathtaking.
Thanks for the comparisons. I will be sending a copy to Rob Oakeshott and Greg Combet. They may not read them but they won’t be able to say they didn’t know. May I suggest letters to BoM asking for comment.
It’s illuminating that the long range forecasters that rely on history and solar cycles seem to have a better prediction record than BoM.
Well, AS, what should they be used for? Do a quick cost/benefit anaylsis please, you know, value for $, assistance to citizens who rely on reasonable forecasts so they can make categorical business and lifestyle decisions, instead of just tossing a coin.
The charts of actual rain and temperature need to have colour codes otherwise it is not possible to make any judgement whether the information is correct or even useful.
The BOM prediction charts are useless. There is a big difference between a 75% chance of above normal rainfall and a 50% chance of 150% median rainfall or even 25% chance of double median rainfall. Where I live the forcast for Jan-Mar 2011 was 70% chance of above median but the actual was 130%of median. I would have forcast on the basis of the rainfall in December and the SOI that there was 100% chance of above median and 50% chance of getting above 150% of median.
Added by WSH – the second link at the top which starts “real world results map…..” that takes you to the BoM page where readers can make those maps – and then see the colour scales.
Agree Cohenite. The people who would most likely use this sort of information are farmers.If they followed these types of predictions then they would not be in business very long. So AS , what is the point of tax payers paying for such information ?
It would be interesting ( if the information was available) to go back say 20 – 30 years to
compare the accuracy of of 3mths forecasts with actual. We might then see the “value” of these faster computers and fancy models.
Ross says:
Agree entirely, good for some research for an enterprising scientist with grant money. Oh, what, there’s none for this. Only if it shows they are right?
Added by WSH 7 May;
Remember the peer reviewed paper from 2005;
“Verification and value of the Australian Bureau of Meteorology township seasonal rainfall forecasts in Australia, 1997-2005″
AL Vizard, GA Anderson and DJ Buckley
Then there is a 2008 paper looking at correlations with SOI
Apparently there is a strand of probability theory (Richard von Mises?) that says that probabilities are meaningless for single events. After looking at these comparisons, and considering the BoM’s qualification on their outlooks, as related by AS, I can see the sense in this approach. Sure enough, a BoM estimated probability is not disproven by the eventual result having been given only a 25% chance. However, that also means that the probabilities are never right and never wrong. Even a 99% estimated probability of hot weather is not “wrong” if it turns out to be cold – it’s just that the 1% happened to get up this time.
If we leave theory aside, and think only of practicalities, the situation looks different. There is only going to be one reality to test the BoM’s outlook against. If the outlook says more than 50% per cent chance of warmer than usual, then the only practical decision one can expect from those sturdy individuals, our farmers and graziers, is to plan on it being warmer than usual. If it turns out to be cooler than usual, then the outlook was a dud tip, and said cockies have a legitimate gripe. If they keep on having legitimate gripes close to 50% of the time, as seems to be the case, then the BoM should give up publishing this stuff until their strike rate improves.