The new seasonal forecast maps developed by the CMCC Foundation Euro-Mediterranean Center on Climate Change (CMCC) are now available on the CMCC Seasonal Prediction System website:
Seasonal forecasts, performed using global numerical climate models, can have a time horizon ranging from one to several months. The feasibility of such forecasts relies on the existence, in the climate system, of low frequency, slower processes, taking place in the stratosphere and at the land surface, as well as in the ocean and in the sea ice. Such processes generate phenomena which last longer than the typical atmospheric synoptic timescale and produce effects on the atmosphere which can last for several months, providing essential sources of seasonal predictability. The most well-known of such phenomena is ENSO (El Nino Southern Oscillation).
CMCC has been contributing with its operational monthly seasonal forecasts to the Copernicus C3S multi–model ensemble seasonal forecast system since 2016.
Starting from the forecast of October 2020, the new seasonal prediction system, CMCC-SPS3.5 (https://sps.cmcc.it/documentation/ and https://www.cmcc.it/publications/tn0288-the-new-cmcc-operational-seasonal-prediction-system-sps3-5), with increased atmospheric and land horizontal resolution and better calibration of some atmospheric physical processes, substituted the previous version (CMCC-SPS3).
The CMCC seasonal forecasts are disseminated every month – currently on the 13th of the month at 13 UTC. They cover a forecast span of six months.
The forecasts are available in the form of graphical products (maps or time series) for a number of forecast variables (e.g. air and sea-surface temperature, atmospheric circulation, precipitation and El-Nino 3.4 index, etc.) at https://sps.cmcc.it/. A full set of CMCC-SPS3.5 seasonal forecast output data is also available for download, both in graphical and numerical form, at Copernicus CDS.