Recent progress and outlook for the ECMWF Integrated Forecasting System

This presentation will provide an overview of recent scientific developments at ECMWF, with focus on the upgrade of the Integrated Forecasting System (IFS) for cycle 50r1.

An upgrade to ECMWF's Integrated Forecasting System (IFS) is scheduled for operational implementation in early 2026.  IFS Cycle 50r1 brings major advances in both the forecast model and the data assimilation system, marking a significant step forward in coupled Earth system prediction. The model upgrade includes the introduction of the NEMO4-SI3 ocean and sea ice model, improved wave-ice interactions, revised vertical diffusion and gravity wave drag in the stratosphere, changes to the convection scheme, a new glacier scheme, and a revisionof the SPP scheme introduced in 2023 that reduces excessive near-surface wind spread in the ensemble. On the data assimilation side, outer-loop coupling has been introduced between the  atmosphere and ocean to provide balanced initial conditions for the coupled forecast model, while further enhancements of weak-constraint 4D-Var introduce time-varying model errors and has been extended to the boundary layer. Cost-efficiency improvements have been made through the use of single-precision trajectories, single-precision ocean model and from reducing the resolution of the first minimisation in the EDA. The system now allows humidity increments in the stratosphere, addressing longstanding issues in moisture analysis at these levels.

A major development of data-driven weather prediction models is the operational implementation (July 2025) of the Artificial Intelligence Forecasting System ensemble (AIFS-ENS). AIFS ENS is trained using a CRPS-based approach, which optimises the probabilistic scores of the ensemble forecasts. It delivers skilful weather forecasts with significantly improved speed and energy efficiency.

The 50r1 update of the ECMWF atmospheric composition forecast led to improved forecast of surface ozone and sulphur dioxide.  A further addition is the routine assimilation of aerosol optical depth retrievals from VIIRS and Sentinel 3. 

Besides the developments for the operational updates, the preparation of the production of 6^th generation atmosphere and ocean reanalyses (ERA6/OCEAN6), the new version of the atmospheric composition reanalysis (EAC5), and the next seasonal prediction system (SEAS6) have progressed well.