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Please note that numbering/ordering does not imply priority. Recent updates are shown in green. Greyed out means no longer current, but these issues can be relevant when examining archived forecasts.

Any enquiries related to the content of this page should be raised via the ECMWF Support Portal (mentioning the "Known AIFS ENS forecasting issues page").

Topic / title	Description	Related activities / comments
General issues
G1. Artefacts at long lead times	Beyond 10 days, unphysical artefacts can emerge in the model, particularly under areas of high elevation. These are particularly visible for mean sea level pressure and temperature at 1000hPa.	Investigations are underway to understand and fix this issue in future cycles.
G2. Over-dispersion	On average, ensemble standard deviation is larger than RMSE of ensemble mean for a range of variables	IFS-ENS and AIFS-CRPS share the same initial condition perturbation amplitude. Re-scaling is under investigation.
G3. Precipitation	Small tp values can occur in very dry regions, visible for long accumulation periods 240h accumulated precipitation	Investigations are underway to understand and fix this issue in future cycles.
Mean Sea Level Pressure

2m temperature


Clouds
C1. Reduced spatial resolution in cloud fields	Cloud fields display features at a lower spatial resolution than many of the other fields predicted by the AIFS ENS. Features have a resolution closer to the 1-degree resolution of the model processor grid.	Investigations are underway to understand and fix this issue in future cycles.