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Forecasters should consider possible deficiencies in model climates when considering extreme forecast index EFI data.  For an example of the effect, see Fig5Fig534.3.1 A and Fig5Fig534.3.2B.  Such effects have also appeared in the extended range ensemble and seasonal forecasts.

Fig5Fig534.3.1A(left): Extreme Forecast Index (EFI) for 2m temperature for Days10-15, ensemble forecast run DT 00UTC 20 June 2017. 

Fig5Fig534.3.2B(right): Cumulative Distribution Function(CDF) for 2 m temperature for Days10-15 in the middle of Lake Superior (red), with M-climate (black).  The initialisation techniques are different for real-time forecasts (using lake surface temperature observed by satellites), and for the re-forecasts (for which this information is not available).  This can lead to the model climate developing anomalously warm or cold lake surfaces and corrwspomdimg 2 m CDF temperature curve (black).   This affects subsequent extreme forecast index (EFI) and shift of tails (SOT) fields.   Here the realistic real-time forecast of 2 m temperature CDF (red) over Lake Superior is thus incorrectly flagged as having a strongly negative EFI value in Fig5.3.1.  

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