Pro Field Report

Basic Information

Observation Date:

March 21, 2022

Submitted:

March 22, 2022

Observer:

SAC - VandenBos

Zone or Region:

Galena Summit and Eastern Mtns

Location:

Boundary/Casino divide (6,500-9,000')

Recent Avalanches?

None Observed

Cracking?

None Experienced

Collapsing?

Isolated

I experienced a few small collapses on low angle solar ridgelines, it seemed like crusts were collapsing into facets sandwiched between other crusts.

Stability Rating:

Good

Confidence in Rating:

Moderate

Stability Trend:

Advanced Information

Cloud Cover:

Mostly Cloudy

Wind:

Light , NW

New/Recent Snowfall:

2-3cm

A pocket of mostly clear skies in the late morning, then high clouds pushed back in and covered the sky through the early afternoon, then slowly, partially clearing into the afternoon/evening. Light NW winds picking up to moderate speeds in the afternoon as skies cleared. 2-3cm of new snow from Saturday night's storm.

Goals were to look at amount of melting and check in on upper pack weak layers.

Cool temperatures and cloud cover prevented wet snow issues from becoming a problem here. Snow surface was refreezing quickly as tree shadows began to grow. Skied good proto-corn at the end of the tour around 1745.

Upper snowpack weak layers: I dug in a slightly wind-loaded location at 8,700'. 3/8 was down 20-25cm under a F to 4F slab, small facets on either side of this interface did not produce propagating test results but were still visually concerning. This layer produced ECTNs in the upper single digits. 1/20 interface was down 40-45cm under a 4F to 1F- slab and presented as a well-developed layer of 2-3mm facets that were cupped, striated, and chained in places. This layer produced repeated unstable snowpack test scores. ECTP 13 and 14, CPST 31 and 28/100 END, PST 34 and 31/100 END. This layer looked quite similar to the weak layer responsible for the recent human-triggered avalanches in the Baker Creek drainage. On a steep slope with a weak layer+slab combo like the one I found today I'd expect you'd be able to trigger an avalanche.

A note on weak layers: the 3/8 interface is well defined and easy to pick out in pits. What I've been calling 1/20 is actually a variety of weak layers that developed in January and February, were buried by small storms, and subsequently faceted again. We lose a bit of precision by describing it that way, but it isn't really possible to point at an individual level in the pit and say with any certainty that it represents a certain date from the January/February period. The weakest portion of this interface is composed of well-developed FC that resemble DH grains (cups, striations, chains).