Dear authors,
Your manuscript has been scrutinized by three expert reviewers in the subject of cyclone clustering. (Unfortunately, one of the reviewers from the first round could not follow up in the second round, and thus I brought in a new reviewer in the second round.) All reviewers agree that your manuscript contains interesting results and valuable information. All three reviewers further agree, however, that the definition of cyclone clustering used in your manuscript is not consistent with a definition that the community has established over the previous couple of decades. Dacre and Pinot (2020) provide a review that seems to be well received by the community (based on citation metrics). All reviewers agree that your definition is consistent with the concept of cyclone families. I trust the expert reviewers that the distinction between cyclone clustering and cyclone families is important, and I agree with the reviewers that blurring an important distinction leads to confusion. Referee #3 provides a clear example of a scenario, in which cyclone families (and your perspective) are not congruent with clustering: “By requiring the tracks to follow similar paths, it excludes some of the serial clustering that would occur from cyclones coming from different directions (which seems plausible if a cyclone developed on a trailing cold front).”
Both reviewers of the second round suggest that the way forward for this manuscript is to refrain from the claim to identify cyclone clustering but rather to use the term cyclone families. I follow the clear (and strong) statement of reviewer #2 in that “the methodology the authors have developed is good in identifying exactly that, namely “cyclone families”. So I would like to strongly suggest that the authors change the title of the manuscript and generally the wording used everywhere to “cyclone families”. This would be a much more precise description of what the authors are actually analyzing with their methodology and would avoid confusion with many papers published about cyclone clustering over the last twenty years.”
Taking a “fresh look” at “established” science problems is an integral part of scientific rigor and advancement. Alternative approaches should not be dismissed lightly. The reviews, however, are convincing in arguing that the manuscript does not take a fresh look at cyclone clustering, clearly put by reviewer #3: “… it is important here to make it clear that this new study is not offering an algorithm that is better than others, rather it is detecting a specific subset of cyclones that are within the extratropical stormtracks. I think it should not be compared so closely to the previous studies as it is specifically choosing something different to look at.” (my emphasis) To be accepted for publication, I would like the authors to follow the consensus recommendations of the reviewers and change terminology. The introduction and the conclusion sections are suitable places to discuss the relation between cyclone families and clustering, where such a discussion would need to acknowledge the definition of clustering as accepted by the community, e.g., as reviewed by Dacre and Pinot (2020).

Best wishes, Michael

Dear Chris and Thomas,
the manscript converges towards a publishable version. A hopefully final round of (minor) revisions, however, is required before acceptance.
Kind regards, Michael

The authors have further clarified their presentation. The manuscript is now acceptable for publication.