Evaluation of ECMWF forecasts, including the 2021 upgrade

This report provides a summary of ECMWF’s forecast performance, covering medium, extended, and seasonal forecast ranges. It includes a short description of the changes implemented as part of the upgrade to model cycle 47r3 in October 2021 and the meteorological impact of the upgrade. There are several so-called headline scores that have been adopted by ECMWF in collaboration with its member states to monitor the evolution of various aspects of forecast skill. The report gives updates on these scores, as well as supplementary scores to help provide a more complete assessment of forecast skill. The primary focus of this summary is the medium range, and specifically the forecast performance for upper-air variables. It is shown that model cycle 47r3 led to an increase in upper-air forecast skill, such that ECMWF’s lead compared to other global centres is being maintained. For surface parameters it is shown that the forecast skill of the Extreme Forecast Index (EFI) has reached a new high point. Over the ocean, where ECMWF has traditionally been leading in terms of significant wave height but not peak wave period, due to 47r3 it now also leads for the latter. On the seasonal timescale, the recent continuation and re-strengthening of La Nina was not predicted well, however the European anomalously warm summer 2022 was indicated in the forecasts with a consistent signal.