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The production of seasonal forecasts, sometimes also called known as seasonal climate forecasts, have experienced a huge transformation in the last few decades: from a purely academic and research exercise in the early 90s to the current situation where several meteorological forecast services throughout the world conduct routine operational seasonal forecasting activities. Such activities are devoted to provide estimates of statistics of weather in the seasonal and monthly time scales, and they lie in a place somewhere between conventional weather forecasts and climate predictions.
In that sense, even though seasonal forecasts share some method and tools with weather forecasting they are part of a different paradigm which requires treating them in different ways. Seasonal forecasts instead of trying to answer to the question "how is the weather going to look like on a particular location in an specific day?", they will tell us , then, how likely is that the coming season will be wetter, drier, warmer or colder than normal. This kind of long term predictions are feasible due to the behaviour of some of the earth system components which evolve more slowly than the atmosphere (e.g. the ocean, the cryosphere)
We consider here as seasonal forecasts both the outputs of numerical atmospheric and coupled, earth system weather or climate models and the derived monthly and seasonal products up to a few months ahead of their initialization date.
Seasonal forecasting within the C3S
The C3S seasonal forecasting products are based on data from several state-of-the-art seasonal prediction systems. Multi-system combinations, as well as predictions from the individual component systems, are available. The centres currently providing forecasts to C3S are ECMWF, The Met Office and Météo-France; in the coming months data produced by Deutscher Wetterdienst and Centro Euro-Mediterraneo sui Cambiamenti Climatici will be included in the C3S
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multi-system.
Currently, there are graphical products available in the C3S web site and public access to the data is provided via the ECMWF WebAPI. From 2018 onwards, C3S seasonal forecast data products will be made available via the C3S Climate Data Store (CDS).Blahblahblah (providers, evolution of the service, etc)
Seasonal forecasts are not weather forecasts: the role of the hindcasts
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