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This shows the return period of the accumulated surface runoff for all ensemble members for all 6 hourly timesteps of the 5 day forecast period (Figure 3). The solid black line ('LEPS mean in the legend of Figure 3) represents the return period of the ensemble mean accumulated runoff. The dashed black lines show the accumulated surface runoff return period of the 25th 30th and 75th 70th percentiles from the ensemble. The vertical dashed line represents the lead time of 48 hours, which is the maximum lead time at which flash flood notifications can be issued. The blue shading shows the ensemble spread of the accumulated surface runoff between the 10th to the 90th percentiles, darker blue shadings are shown closer to the 50th percentile.
The yellow, red and purple background shades represent the 2, 5 and 20 year return period thresholds respectively. The values P(T>x)= show the maximum exceedance probabilities of the 2, 5 and 20 year return period thresholds across the 5 day forecast period.
