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The ensemble consists of one unperturbed member (the control) and 50 perturbed members that are similar to the control but their initial states and model physics have been perturbed to explore the currently understood range of uncertainty in the observations and the model.  A set of medium range re-forecasts provide a basis for the medium range model climate M-Climate.

The medium range ensemble 10 day forecast runs with data analysed from the short cut off analysis (SCDA).  Perturbations are derived.   ????? The medium range ensemble 15 day forecast runs 10 day and 15day ensemble forecast run with data analysed from the short cut off analysis (SCDA).  Perturbations are derived.   ?????  

When averaged over many forecasts each of the perturbed members has lower skill than the control though any individual forecast might show a higher skill.  There is a range of products to present the information from the ensemble in different ways and appropriate for different uses.  These include probabilities, clusters of alternative scenarios, and tropical cyclone and extra-tropical cyclone products.  Certain important products are based on, or directly show, anomalies relative to the M-climate, such as meteograms and the Extreme Forecast Index and Shift of Tails (EFI/SOT).    The ENS products and chart presentations show where and when weather may deviate from the average for the location and time of year, and if such an anomaly could be extreme.

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