We are pleased to inform you that ECMWF is making good progress with the forthcoming implementation of cycle 45r1 of the Integrated Forecasting System (IFS). The cycle is now entering the release candidate phase. Test data are available through the dissemination. Details of the meteorological and technical changes in this cycle, together with information about the forecast performance (including scorecards), can be found at: https://software.ecmwf.int/wiki/display/FCST/Implementation+of+IFS+cycle+45r1 The implementation of the new cycle is scheduled for Tuesday 5 June 2018. The first operational run using the new cycle will be the 06 UTC analysis and forecast in the Boundary Conditions Optional Programme on 5 June followed by the 12 UTC main assimilation and forecast. The monthly forecast extension to the ensemble will be run with the new IFS cycle for the first time the following Thursday 7 June 2018. Please note that there will be no further communication on the implementation of 45r1 unless the implementation date changes.