Clarification of units
Are the results in inches of snow or inches of SWE?
I also have questions about the detrending but the question may be difficult for me to describe. But here is a try.
Usually when comparing things you try to move them to the same year often the present time or the past time but it does not matter as long as it is the same year. But doing that for this analysis (using climate models) would defeat the purpose of the analysis except that for some purposes you are working with the average of all years and for other purposes just El Nino years and also a subset of El Nino Years to Moderate to Strong El Nino years.
So can you clarify what you mean by detrending and how you did it?
By the way I just published an article on your post at https://econcurrents.com/2023/11/23/el-nino-and-snowfall-november-24-20… All corrections to what I said would be appreciated and probably should be posted as comments to my article but could be published here.
I thought you wrote a great post. So thank you.