Causes of improvements to NWP (1979 – 2009)

1. CAS-XV TECOview from the back of the roomDavid BurridgeWMOTHORPEX International Programme Office

2. Causes of improvements to NWP(1979 – 2009) For large-scale variables, NWP systems are improving by 1 day of predictive skill per decade. In priority order, this has been due to: • Model improvements, especially resolution. • Careful use of forecast & observations, allowing for their information content and errors - achieved by variational assimilation e.g. of satellite radiances. • 4D-Var. • Better observations.

3. In more detail • Steady improvements in skill in traditional measures such as 500hPa geopotential (~1 day per decade). However in weather parameters such as precipitation, cloud etc, and in the Tropics progress is more rapid (~ 1 day per 7 years). • Improvement in ocean-wave prediction. • Increased resolution and improvement in “physics” for all systems • Also Ensemble systems are improving at ~1 day per 7 years. • Much improved representation and forecasting of severe weather in general – mid-latitude systems, tropical cyclones ..... • Advanced assimilation methods that enable more effective use of vast amounts of satellite data • Encouraging progress in analysing and forecasting atmospheric composition • Development observations in process studies leading to increasingly sophisticated parametrizations including field experiments • Successful FDPs and RDPs

4. Future - increasing capacity building • Organization of training sessions on a regional basis as a means to increase involvement in prediction systems, product development and use – general forecasting, high impact weather, societal and economic applications • Training also needs to include training on verification techniques and use of ensemble prediction • Emphasis on regional problems – severe weather, cyclones, heavy rainfall, hydrology ……. • Instructors need to include regional examples • Language

5. Future - science • WWRP Strategic Plan • Basic modelling issues – resolution and parametrization • Handling of the tropics particularly organised convection, tropical cyclones and extra-tropical transition and interactions - YOTC • The required initial conditions and implied observational coverage – assimilation (scalability and formulation), detection of systems in their early development, design of appropriate field and targeting experiments & at least preserving what data we currently have • Improving the processing and uses of ensemble predictions • Sound FDPs and RDPs - collaboration with CBS • Seamless prediction of weather, surface, hydrology, ocean-surface conditions and atmospheric composition from a few hours to a season ahead - collaboration with WCRP • Training – prediction systems, verification & product use/development including Ensemble Prediction • Societal and economic applications developing