Page History

...

Forecasters should consider possible deficiencies in model climates when considering extreme forecast index EFI data.  For an example of the effect, see Fig534.A and Fig534.BFig5.3.4-1 and Fig5.3.4-2.  Such effects have also appeared in the extended range ensemble and seasonal forecasts.

Image Removed

Fig534.A(left)Fig5.3.4-1: Extreme Forecast Index (EFI) for 2m temperature for Days10-15, ensemble forecast run DT 00UTC 20 June 2017.

Image Added

Fig534.B(right)Fig5.3.4-2(: 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 Fig5.3.4-1(left).  

More information is given in Documentation and a full description of ERA5.

...