Chance of extremes
Meat & Livestock Australia October 24, 2023
The chance of extremes maps show the predictions for unusually high and low rainfall or temperatures over one week, two weeks, one month or three months. These maps are an extension of the chance of above median maps.
The colouring in the maps indicates the chance or likelihood of experiencing extremes in rainfall or temperature as shown in Figure 6. The increasing intensity of colours used in the maps correlates to increasing chance of rainfall or temperature in extreme deciles. In a neutral forecast, the likelihood of any outcome is 20%. As such, the likelihood of an extreme dry or cold (decile 1 & 2) or extreme wet or hot (decile 9 & 10) is also 20%, and no distinct indication can be drawn from the forecast model results. Areas without data are represented in grey.
In the example in Figure 6, the map shows an above 80% chance of rainfall being in decile 9 & 10 of historical data for central Queensland. This means the likelihood of extremely wet conditions is four times higher than the chance of median rainfall typical for that time of year.
The chance of extremes of map can show the likelihood of extreme cold events, however, it can’t indicate a frost. Minimum temperatures may give an indication of frost potential at certain times of the year, and this can be explored further using other Bureau tools and seven-day forecasts.
Figure 6. An example of the Climate Outlook Map forecasting unusually wet conditions issues during September 2022 for the two weeks between 10-23 September across eastern Australia. Reproduced from Agriculture Victoria’s eLearning course ‘Using seasonal climate prediction tools’.