The manuscript “Long-term ensemble forecast of snowmelt inflow into the Cheboksary reservoir under the differently constructed weather scenarios" by Gelfan et al., was reviewed by 3 experts in the field of hydrological seasonal forecasting. This investigation is also within the score of the Special Issue “Sub-seasonal to seasonal hydrological forecasting”, however as pointed out by the 3 referees, major revisions would be needed for potential publication in HESS. All highlighted the need for major revisions, on which I also completely agree with. Despite this decision, the referees and I see the scientific interest of this article, particularly after addressing all the comments.

All three referees provided important input on how to substantially improve the content and structure of the manuscript. Some of the key concerns are driven by the need for: 1) comparison of the 2 investigated methods (ESP and WG) with the state-of-the-art methods currently being operational, and hence the analysis will not only have a scientific relevance but also contribute towards operational improvements; 2) deeper understanding of the drivers that influence the skill, and further decomposition of the overall predictive skill into reliability and resolution of forecasts, 3) structural edits to communicate better the present operational challenges in this reservoir and hence the scientific significance of this investigation.

I am pleased to see that despite the comments of major significance from the referees, the authors manage to propose a number of changes that satisfactorily address the referees’ suggestions/concerns. The authors planned in detail on how to address every single comment, including also additional numerical experiments (results also presented in the Auhors’ reply). I also believe that now there is a clear (and highlighted) scientific contribution from this investigation. I would like to ask the authors to proceed to their proposed changes and submitted an improvement manuscript. Here, I would like to raise my personal suggestion that there is no need to provide results from a large list of metrics, particularly since some of them are meant to extract the same information from the forecasted signal. Therefore please select a set with no redundant information.

Best regards,

Two referees provided comments on the revised manuscript, whilst both highlighted its overall substantial improvement. The manuscript is indeed refined and close to its final acceptance for publication in HESS. Currently there are only some minor revisions needed to update the literature with relevant papers (see report from Referee #1) and also to emphasise more on the discussion/process understanding rather than a sole presentation of the results (see report from Referee #2). Although progress has been made on the latter issue, one of the referees (and I would personally agree with this decision) would like further clarification.
I would personally ask the authors if the title is grammatically correct. To me it should have been “Long-term ensemble forecast of snowmelt inflow into the Cheboksary reservoir under two different weather scenarios"
I am looking forward to receiving your fine-tuned manuscript.

The authors successfully addressed the minor comments from the two referees resulting into an improved manuscript. Based on a personal review, I can accept the manuscript for publication in HESS. Congratulations to the authors for this interesting article and contribution to the Special Issue.
Best wishes,
Ilias Pechlivanidis