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• • for >4°C above climatology ensemble 90% probability actually occurred 85% of the time - the wide distribution of forecast probabilities suggest some moderate confidence in the implied reliability. 
  • for >8°C below climatology ensemble 90% probability actually occurred 85% of the time - but the very few forecasts of high probabilities suggest very low confidence in the implied reliability

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Fig8.3.5-5: Reliability Example reliability diagrams for 2m temperature based on July starts of the seasonal the seasonal forecasts for months 4-6. 

• left for the tropics - a slight tendency towards over-confidence, more especially where forecasting that this event (warm anomalies) will happen.
• right for Europe - a tendency towards over-confidence, though the sample size for high confidence forecasts is small, making the plot noisy.

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Fig8.3.5-6: Reliability Example reliability diagrams for rain based on July starts of the seasonal forecasts for months 4-6:

• left for the tropics - a tendency towards over-confidence.
• right for Europe - forecast not reliable at all (so should not be used, unless there are exceptional circumstances that warrant an expectation of skill that is ordinarily not there).

Fig8.3.5-7: Example ROC diagrams for Europe based on July starts of the seasonal forecasts for months 4-6:

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