Timeline graphs display a timeline of recent climatic observations from the previous weeks and months, against historic averages, to illustrate what might happen in the future. The box and whisker plots show the variability of the 99 model runs for the four weeks or five months ahead. To make it easier, the shading of the graph aligns with the markers of the box and whisker plot to show the recent rainfall deciles (recent average rainfall indicated by the solid black line) and the predicted deciles (predicted medians indicated by the dotted black line) as illustrated in Figure 9. The timeline graph can be accessed by selecting a location on the map or entering a location in the search function.
As with the decile bar charts, the timeline graph includes star ratings to indicate past accuracy for the outlook. The length of the whiskers and size of the box indicate the range of predictions. So, if most of the 99 model runs are within a tight range (compact box and shorter whiskers, e.g. July in Figure 9), it provides greater confidence in the prediction. However, as we’ve seen with the decile bar charts, any outcome is still possible.
Figure 9. Five-month timeline graph for predicted rainfall in Dubbo, NSW. Reproduced from Agriculture Victoria’s eLearning course ‘Using seasonal climate prediction tools’.