Please see attached file. 

This is a comprehensive paper looking at the firn conditions on the Juneau Icefield from both in situ measurements and a firn model. The measurements are repeat cores from the 2024 summer season. The firn model is forced by climate reanalysis data between 1980 and 2019. The paper finds decreasing firn thickness and cold content and increasing melt, runoff, and firn temperatures during the modeling period, and variable LWC and refreezing features within the cores.

Overall, I think this is a useful contribution to the firn measurement and modeling community. Wet firn is extremely difficult to measure and monitor, and this paper includes some of the first measurements of LWC in firn.

Most of my comments are inline in the PDF, but I have summarised some of the broader comments here.

Moderate notes

• The paper is quite long, so it may be useful to look for areas where concepts/results are repeated or not needed because they don't relate directly to the reported results. For example, you may be able to reduce or remove some sections in Introduction/Firn Hydrology, e.g., firn aquifers are not discussed much in the results or discussion, but are discussed quite a bit in the introduction.
• The GPR is not discussed at all in the results. Either a section should be added to the results about tracking melt features in the GPR and/or the variability of melt features seen in the GPR, or there should be some mention in the methods & discussion about why this data should be included in this paper and/or why it wasn't analysed.
• Figure 3 makes it very difficult to see how or if ablation was taken into account because all the cores are shown starting at the same surface height. I would recommend plotting these so that they are shown at depths relative to the snow surface of the earliest season core at each location. Otherwise, please clarify how ablation was taken into account when determining the relative depth of the cores & layers.
• The "flashier" hydrology in the Discussion section isn't sufficiently motivated or supported by citations. While it seems plausible, this could be better supported by looking at work looking at seasonal snow or rain-on-snow events, but in general would require looking at downstream hydrology or looking at how runoff vs. melt events is changing.
• I am not completely convinced still that the decrease in the number of days with high cold content is solely responsible for the increase in runoff and earlier regime transition --- decrease in FAC and thinning firn packs (resulting in less pore space for water) likely also play a role. If this is your argument, I think it needs to be strengthened by showing correlations between cold content and runoff in the results or discussion and/or more explicitly working the reader through the physical premise for your argument.

Minor notes

• Check for consistency in the verb tense in the methods/results - the writing often switches between past and present tense, which can make it difficult for the reader to follow along. For example, in the paragraph starting at line 295, the first sentence uses past tense ("were") and the subsequent paragraphs use present tense ("are"). Elsewhere in the stratigraphy section, past tense is used; in the GPR section, the tense switches to present.
• Differentiate between latent and sensible heat. Only latent heat is mentioned throughout; meltwater (and rain) also introduce sensible heat, and in some locations latent heat is mixed up with sensible heat (latent heat -> phase change; sensible heat -> warming or cooling without phase change)
• Watch for language that attributes cause or implies causality where none has been proved. For example, the abstract says "decreasing firn cold content caused increasing meltwater runoff from the firn", but in the results, no causality (e.g., statistical analysis; physical argument) is put forth.
• In the Methods section, add more detail about the model (e.g., clarify what kind of bucket scheme was used), how the spinup was performed, and how the surface density was chosen.
• In general, the lightest colors in each plot, and particularly the lightest color dotted lines, are very difficult to see. I would recommend either making the lines thicker or use a darker color.
• There are some (though few) LWC measurements in firn, including Samimi et al. 2020 who measured change in dielectric permittivity in the firn and Heilig et al. 2018 who used upward looking GPR to measure liquid water content in the firn.