Hello, I am reaching out in order to get some more information/guidance on the process of clustering in the ECMWF medium-range product. As someone can read in this documentation (https://www.ecmwf.int/en/forecasts/documentation-and-support/ens-cluster-products), the clustering is performed over the following time windows: 3-4 days, 5-7 days, 8-10 days, 11-15 days. Although it is described that the members remain in the same cluster within one time window, I am wondering how the synoptic consistence can be guaranteed when going from one time window to the other. And why is there not a continuation of the period, i.e. days 3-4, 4-6, 6-8 etc.

Thank you in advance for your time!