> only 6ish deaths below the median.

I think you fail to make this valid point strongly enough. The median for any given date in the sample looks not much more than 15, but that's a cumulative total over a 15 year span. So the median for any unique individual day is ~1, and 1 is the below median minimum.

Other than Halloween, the sliver of not-noise should mostly be around weekends and holidays. As seen with Covid, the number of deaths decline around these times and peak the day after them. A simple matter that hospital administrators and state health board workers are disinclined to work on days off.

This sort of data isn't precise down to date of mortality incident or subsequent hour of death. It's when the report is recorded--generally M-F; 9-5.