Reliability diagram for the first unbalanced fold of the 3-fold cross-validation considered in the present study, spanning the 24–48-h period. Confidence bars show the 95% bootstrap confidence interval around the mean. Shaded regions show the area of skillful forecasts. The horizontal and vertical lines show the prevalence-based probabilities of the event for forecasts and observations. The inset shows the sharpness diagram (relative to the test in 2021) illustrating the relative frequency of lightning occurrence predictions (abbreviated as 'Count') at different probability levels. This diagram also provides the number of sampling (Count) used to compute the 95% bootstrap confidence interval.
