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

• left for temperatures for 2m temperatures in the upper tercile - the Hit Rate is slightly better than the False Alarm Rate indicating that the forecast system has some limited ability to discriminate occasions when warm events are likely from occasions when they are not. 
• right for precipitation in the upper tercile - the Hit Rate and False Alarm Rate are similar throughout indicating that the seasonal forecast system has no ability to distinguish occasions when it will be wet from occasions when it will not.

Anomaly Correlation Correlation 

Anomaly Correlation Coefficient (ACC) charts give an assessment of the skill of the forecast.  They show the correlation at all geographical locations in map form.

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