Eastern Sierra Avalanche Center » Public Observation

Observation Date:

May 7, 2023

Submitted:

May 7, 2023

Zone or Region:

Mammoth Lakes

Activity:

Skiing/Snowboarding

Location:

TJ Bowl, chutes above.

9am, 9000ft in lakes basin observed a 3-4cm sun/wind crust on windward / flat terrain. Wind deposits 10-20cm in depth also present on the leeward side at all elevations on the climb up. No wind / storm slabbing noticeable until above 10000ft.
While hiking up the steep, NE wind-loaded chutes at 10500ft+ around 11:30am we noticed a fresh wind / storm slab above a melt-freeze crust, the slab was about 3cm thick and below about 3cm of fresh unconsolidated snow. The crust below the slab was about 10cm deep. We noticed little signs of instability at this elevation, besides 3cm deep loose avalanches and storm slab potential. We stopped hiking before the ridgeline as the snow became deeper and difficult to get a good grip on for the climb.
The avalanche was triggered below ridgeline, just at/above treeline, roughly 9750ft, on wind-loaded terrain after we skied the chute.

Comments:

6-8" crown, 30-40ft wide ripped out the whole chute. All seemed to be wind loaded snow on a freeze-thraw crust, also in a chute / perforated area. I did a top cut in the chute and most of it slid, the rest slid as I skied down and managed to get out safely. This slide was unlikely to even knock someone off their feet but it did propagate fairly widely. Another avalanche nearly identical to this one was triggered by skiers to the skiers' left of the chute I skied.