2021 is a very low snow year. Terrible for California as far as the water supply and fire danger. It will allow early cross country travel in the Sierra.
The unlabeled dark blue line (shame on whoever made these graphs) is the 2020-2021 snow level. If you compare to 2019-2020 you will see the April 1 levels were similar, but in 2020 a lot of snow dumped in April and essentially none in 2021, so by early June the snow is essentially gone.
Uncle Tom's hiking pages / tom@mmto.org