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IFS models produce a wide range of output products available online through the website in chart form or or by dissemination or extraction in a GRIB format.  Presentation through ecCharts allows output data to be combined and displayed in a user-friendly way tailored to the needs and requirements of the user.  An individual ensemble member forecast or the HRES forecast is a deterministic forecast. 

Relation between deterministic and probabilistic forecasts 

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• identify the predictable scale,
• dampen forecast jumpiness,
• estimate the overall confidence
• draw attention to possible alternative developments, in particular those which involve extreme or hazardous weather events.
  
  

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Categorical forecasts imply a confidence that may not be justified and ECMWF suggests a more probabilistic approach should be used.  Nothing undermines public confidence more than “jumpy” forecasts where forecasts change, sometimes radically, and in particular in connection with anomalous or extreme weather events.   A bad five-day forecast will be identified as such only after five days; a “jumpy” forecast will be identified immediately to the exasperation of the user.   Although ensemble forecasts must, by necessity, be "jumpy" to some extent, there is no reason to convey this “jumpiness” to the public by basing a forecast solely on the very latest NWP output.  This can best be avoided by making active use of uncertainty information derived from recent ensemble forecasts.

Probabilistic frameworks can and should be adapted whenever specific user requirements have to be taken into account; some examples are given in the appendix.  Any member of the ensemble could be considered deterministic, but in general the skill of a singe member is less than the skill of the ensemble mean and a single member gives no information on the confidence that may be placed on its results.

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