Dear authors,
after a careful reading of your submission and considering the detailed reviews that have been provided by two referees, it is quite obvious that your manuscript needs to undergo substantial (i.e. major) revisions before being considered further for publication in HESS. Both authors have stated the need for a stronger case being made around the main message you want to convey (i.e. regional ensemble forecasts for an early flood warning system and how this relates to the state-of-the-art), the degree of sophistication of statistical analyses, the way how results may support your discussion and the subsequent conclusions. The revised version of your manuscript will have to take into account all the main statements and suggestions for improvement made by the referees - as a prerequisite for improving the manuscript and allowing further consideration in the review process. Please note that reception of a revised version of your manuscript will not automatically guarantee publication - your manuscript will undergo a second full review process.
I am looking forward to receive the revised version of your manuscript.
Best regards,
Laurent Pfister

Dear authors,
following up on the review receveived on your revised manuscript, it is obvious that there are still some pending issues/open questions that need to be considered prior to further processing of your manuscript and final acceptance. These points concern methodological aspects (e.g. clarification re- figure 7, equation 1 needs verification, additional technical aspects as listed in the referee's review).
Thank you for considering very carefully these points before submitting the revised version of your manuscript.
Best regards,
Laurent Pfister

Dear colleagues,
following the assessment of the latest iteration, your contribution is now close to final acceptance. One last technical aspect remains: please modify in the abstract the following sentence 'Best Discharge-based Drainage indexes (both deterministic and probabilistic) are defined to the aim of forecasting hydrological stress conditions and related uncertainty' by clearly identifying the acronym BDD that is used further below in the abstract and main text. A suggestion in this respect could read as follows: 'Best Discharge-based Drainage indexes, BDD (both deterministic and probabilistic), are defined to the aim of forecasting hydrological stress conditions and related uncertainty'.
Best regards,
Laurent Pfister