Long-range forecasting and the Global Framework for Climate Services

Abstract

We describe the progress in the international coordination of long-range forecasting fos- tered by the World Meteorological Organisation (WMO), specifically for the seasonal to interannual timescale. Coordination has been achieved through the creation of new infrastructure, notably 11 Global Producing Centres (GPCs) for long-range forecasts, and definition of operational standards in forecast output and associated material. Examples discussed show improvements to the integration, usefulness and operational delivery of long-range forecast products to the world-wide climate com- munity. Products are in wide use, and cover both predictive information, up to 6 mo ahead, and ver- ification information indicating forecast quality. Proposals for future expansions of the role of GPCs are discussed, with a view to addressing the challenges presented by the development of the Global Framework for Climate Services. In particular, implementation of regular WMO-coordinated Global Seasonal Climate Updates is proposed, to provide authoritative, readily accessible advice on the state of the global climate and prospects for the next season. In addition we argue that the skill benefits provided by decadal-range predictions initialised with the observed climate state, relative to unini- tialised (IPCC-type) predictions, are sufficient to begin similar international coordination in multi- annual-to-decadal prediction, through extending the role of those GPCs that are developing decadal- prediction capability.