Decile bar chart

The location-specific decile bars for rainfall and maximum and minimum temperature show the forecasted probability of a given range of rainfall or temperature outcomes. The chart can be accessed by selecting a location on the map or entering a location in the search function. 

The forecasted probability of a given range of rainfall or temperature outcomes is compared with the typical probability of 20%, indicated as the dotted grey line in Figure 8. In this example, for the forecast shows that 28 from 99 forecast model runs fell into deciles 1 & 2 (unusually dry weather) which is nearly twice more likely than the likelihood of median rainfall for that time of year. However, note that the likelihood of the other ranges remains. For instance, there are still 11 out of 99 model runs that fell into deciles 9 & 10 (unusually wet weather) which means other outcomes (besides deciles 1 & 2) are still possible. 

The tool’s infographic includes the historical median rainfall, which in this example is a historic median rainfall of 61mm for Clear Lake (VIC) during the period February-April. In some locations the median rainfall can be 0mm at certain times of the year. In those instances, the range of likelihood of rainfall falling in certain historic range for the given period is not the meaningful. 

The star ratings beside the likelihoods indicate the past accuracy of the outlook. If the model has been reasonably successful at forecasting for this location and time during the past, it receives three out of three stars – a highly accurate result. Two out of three stars indicates medium past accuracy, and one out of the three stars indicates low past accuracy.