Light rain/mist in the morning gave way to broken clouds and later to scattered cloud cover, no blowing or drifting snow, no new snow available for transport.
We did not witness any avalanches, although we did see some spindrift and sloughing from the cliffs above Lake Serene. We observed recent avalanche activity in the apron below the cliffs/ above the lake. These slides likely occurred from snow falling from cliffs after the snow earlier this week.
Snow depths at lake level (2560ft) ranged from 2-3 feet with a lot of spatial variability. The snow was not supportable when you deviated from the bootpacked trail, and it was easy to punch through the snow surface as deep as your hip. The snowpack was mostly isothermal old snow, though from our vantage point at the lake looking up to Mt. Index it appeared there was new snow at upper elevations (5000-6000ft), and lots of rime clinging to the cliffs. Snow cover was patchy from 500-1500ft and mostly consistent 1500ft and above besides some exposed rocks and creek drainages. The trail to Lake Serene passes through multiple historic avalanche paths. While we did not see evidence of recent activity on the large scale slide paths, which had scrubby foliage and some maple stands in the track, we discussed the possibility of a rain event increasing our level of concern with large paths at mid-lower elevations.
While we did not see any evidence of wind slab and the snow we traveled through was mostly isothermic, upper elevation pockets of hanging snow likely have wind slab problem.