Subseasonal to seasonal (S2S ) prediction--2 weeks to a season ahead--is increasingly filling the gap between weather and seasonal climate forecasts, helping provide early warning of high-impact events such as tropical cyclones, floods, droughts, heat, cold waves and their compound impacts to society. As the S2S forecast skill continues to improve through a better understanding of physical mechanisms involved, model advances and statistical calibration, more products are becoming available for decision makers in terms of applications and services.

This session welcomes contributions on all aspects of S2S science, including physical mechanisms (e.g. tropospheric interactions with the ocean/sea-ice, land surface, stratosphere, prognostic aerosols, MJO, tropics-midlatitude-poles teleconnections, cross-timescale interactions), model evaluation and diagnostics, predictability and prediction studies, extreme events, Model Output Statistics (calibration, verification, including Machine Learning), and climate services development (forecast formats, user-selected thresholds for exceedance probabilities), value and communication. Contributions making use of the S2S/SubX databases are particularly encouraged.

• WCRP: World Climate Research Programme -