Since the SubX models are initialized on different days, producing an MME becomes a challenging problem (e.g., Vitart et al. 2017). In SubX, we choose to align the verification dates of each model to produce an MME so that skill could be assessed for the same verification period in observations. Additionally, this choice reproduces well the setup for weekly real-time forecasting. Following the same procedure used by CPC for producing real-time forecasts, Saturday is defined as the first day of a given week. All reforecasts for all models that are produced during the prior week (previous Friday–Thursday) are used to produce an MME forecast for weeks 1–4 individually, where week 1 is defined as the first Saturday–Friday interval. Friday initializations are not included in an attempt to mimic real-time forecast procedures. In real time, forecasts provided after 0800 local time Thursday cannot be processed in time to be used by the forecasters because forecasters must review forecast guidance on Thursday and issue the forecast on Friday. This procedure, which also involves forming averages of daily forecasts over the appropriate week, is repeated for weeks 2–4. Weeks 3 and 4 are then averaged together to produce week 3–4 forecasts. Using this procedure, a multimodel ensemble mean, equally weighted by model can be produced by averaging the ensemble means of each of the models for their week 3–4 forecasts. There are some potential drawbacks to this procedure. For example, some models will contribute older forecasts to the MME than others, depending on their initialization date. The extent to which decreased skill with longer lead time is balanced by increased ensemble size and model diversity in such an ensemble remains an open research question to be addressed in future research. Additionally, since the period over which forecasts are obtained is Saturday–Thursday (a 6-day period, used to mimic the 6-day period of real-time forecast initializations) and some of the models initialize once every 7 days, there are times when a model will not be included in the MME, depending on how the reforecast dates fall. For example, this occurs with the ECCC-GEM model in approximately 13% of the weekly forecasts. Finally, in rare cases, it is not possible to produce a week 3–4 forecast for the ECCC-GEM model since part of week 4 is not available due to the reforecast initialization day and 32-day reforecast length.