I then traversed across the slopes below Round Top (10381') with ice axe and crampons, entering the couloir around 11am, seeing the footprints of other parties.
The couloir forked about a third of the way up. The footprints led right, but I took the left fork, and got out my second tool to enhance security, sometimes plunging, other times daggering, mostly practicing pied troisieme. I probably should have kept closer to the center of the chute, but since it curved to the right I often found myself closer to the left side.
In some places the snow had an icy crust on top that I punched through, and in one place it had definitely hardened into something like neve (but not yet alpine ice) - it took the picks well. For some odd reason this gave me a glimmer of hope that this year's Sierra alpine ice season would be good...
I made my way to the couloir exit, just below the east summit, which is the higher one at 10381', and clambered up the snow/rock slope. I had not expected foul weather to move in until evening, but it was apparent from the sky that something dark was coming in from the west. Still, the occasional breeze was pleasant. I ate lunch quickly, took some pics, and headed down. While snow remained on the north-facing slopes, it had mostly melted from the south slopes. Getting back down to the saddle between the the Sisters and Round Top was mostly a class 2-3 scramble.
Once there I decided to head up the east Sister, which was mostly a matter of scree surfing. The west Sister looked like no more than class 2-3, but by that time the clouds were definitely lowering and the wind had picked up. I decided it was time to get out of there.
The descent back to my snowshoes was mainly a matter of plunge-stepping, and I enjoyed some low-angle glissading back down to Winnemucca Lake, where I marched out asap, feeling a few snowflakes. Back at the sno-park I gave a plastic bag to a cyclist who had not expected the change in the weather and needed something to block the cold wind on his descent.
By the time I was driving past Kirkwood around 4 the snow flurries had started.
-- some pics here: http://rhysw.com/round_top200504