Model upgrade increases skill and unifies medium-range resolutions

An upgrade of ECMWF’s Integrated Forecasting System (IFS) to Cycle 48r1 implemented on 27 June has substantially improved the skill of the Centre’s weather predictions and has increased the resolution of medium-range ensemble forecasts.

The horizontal resolution of medium-range ensemble forecasts (ENS) has increased from 18 to 9 km, which is the same resolution as the current high-resolution forecast (HRES). In the future, HRES and the unperturbed control forecast of the ensemble will be merged.

In addition, configuration changes for the extended-range ensemble forecast result in substantial improvements in forecast skill and utility for users.

There have been many other changes in the forecast model and in data assimilation, leading to much-improved skill scores. The largest forecast skill improvements are associated with the ensemble forecasts because of the ENS resolution upgrade. For example, most ENS scores of surface variables are improved by 2% to 6%.

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