- JoNova - https://joannenova.com.au -

BOM September failure — but who can predict the climate a whole month ahead?

The World’s Best Practice climate models predicted Australia would be hotter than normal in September, instead the maximum temperature anomaly was 1 to 5 degrees below average across most of Australia.

That long range prediction was made all the way back on August 21. Four weeks later it was obvious it was wrong.

BOM, Bureau of MEteorology, Australia, temperature, September 2016, prediction, failure.

Prediction of a hot September versus actual outcome. (Click to enlarge).

Thanks to Warwick Hughes who saw this failure coming and The Marcus Review who points out the mismatch and goes on to log how much the BOM predictions for October have transformed from hotter than average to cold cold cold.

The BOM bravely predicted Tasmania would have an 80% chance of having hotter than average maximums. Temperatures ended up being spot on average. What’s 80% certainty worth? About the same as 95%.

Thanks to Chris Gillham who pointed out the big cold blob of ocean surrounding Australia on the south and west that gave Perth its coldest ever September nights. Wasn’t that cold blob present on August 21 when those models were run? On August 25th, the BOM predicted Perth’s chances of being cooler than average at 50:50. Toss a coin, or use a climate model? The prevailing winds for Tassie come straight of the cold sea.

9.8 out of 10 based on 119 ratings