Sawtooth Avalanche Center

Public Field Report

Observation Details

Observation Date:
March 31, 2020
Submitted:
March 31, 2020
Zone or Region:
Galena Summit and Eastern Mtns
Activity:
Skiing/Snowboarding
Location:
Butterfield

Signs of Unstable Snow

Did you see shooting cracks? 
Yes, Isolated
Did you experience collapsing or whumpfing? 
Yes, Isolated

Observations

Toured up butterfield today to about 9000 feet (the wind told me to go home before reaching the top). Weather was pretty variable in the morning, alternating between bouts of sunshine and snow squalls. The storm really picked up at 9000 feet at around 11:00 am. The SW/W winds were absolutely cranking and rapidly loading leeward slopes. I dug two pits on my way up, one on a NW slope at 7700 feet and the other on a NE slope at 9000 feet. Got propagating ECT results in both pits (ECTP9 at lower elevation pit down 25 cm and ECTP14 at upper elevation pit down 35 cm). Both failures occurred on the same layer. Did a PST in the upper elevation pit and got a pretty startling result of PST 20/100 to the end, although this came at no surprise given all the rumbling collapses I was experiencing. This layer was pretty touchy for me with this new load, and I expect it’s significantly sketchier at upper elevation slopes getting loaded even further. The lower elevation snowpack on N aspects was not confidence inspiring. I was sinking straight to the ground and wallowing in facets as soon as I popped out of my skis, although there wasn’t much slab present aside from the new snow. HS was 100cm in my first pit and 160 in my second.

Media

ECTP9, N/NW aspect, 7700 feet, HS 100cm

Advanced Observations

Observed Avalanche Problem #1: 
Persistent Slab
Comments: 
Got isolated collapses on the north half of the compass in the new snow, likely failing on the recent buried layer of near surface facets. This layer was reactive in stability tests and present at most elevations on N/NW/NE aspects. There was around 25-35cm of snow sitting on top this layer, dependent on elevation and wind load.