Meteorological and hydrological centres around the world are looking at ways to improve their capacity to be able to produce and deliver skilful and reliable forecasts of high-impact extreme events at sub-seasonal timescales (beyond 2 weeks). Improving sub-seasonal predictions, assessing their skill and uncertainty, and exploring ways to communicate their benefits to decision-makers are significant challenges. The S2S WWRP/THORPEX-WCRP joint project (http://s2sprediction.net) is embracing all these challenges and, to promote this research, has created a new database with a set of multi-model s2s reforecasts and forecasts freely available to the community.

The over-arching theme of the session will be the discussion of s2s sources of predictability, forecasts and socio-economic applications of high-impact climate services. Thus, this session invites contributions involving (but not only restricted to) physical mechanisms, statistical and dynamical model methodologies, cross-timescale interactions, Model Output Statistics, verification, uncertainty quantification and climate services involving s2s forecasts with application to water management, droughts, floods, energy and health. Participants are especially encouraged to present contributions and discuss strategies to bridge gaps between stakeholders and actionable s2s tailored products.