Pro Field Report

Basic Information

Observation Date:

February 3, 2021

Submitted:

February 5, 2021

Observer:

SAC - VandenBos (off duty)

Zone or Region:

Galena Summit and Eastern Mtns

Location:

Hyndman Creek (6,500-9,500')

Recent Avalanches?

Yes

Cracking?

Widespread

Collapsing?

Widespread

Stability Rating:

Poor

Confidence in Rating:

Moderate

Stability Trend:

Steady

Advanced Information

Cloud Cover:

Mostly Sunny

Temperature:

teens F (estimated)

Wind:

Light , NW

New/Recent Snowfall:

12-15 cm HN from late Tuesday/early Wednesday storm (buried 2/2)

Clear and cold, light to moderate northerly winds increasing later in the day.

NW @ 7,500', HS=110cm. HN24=12-15cm. 1/27 down 50-60cm. In this location, there was buried SH present here, which produced some rough shears and was unreactive in ECT. 5-8cm down from 1/27 interface I found a second layer of buried SH (suspect this is the 1/12 interface). This was similar in appearance to the layer above (5-10mm standing xtals) but was reactive in ECT (ECTP 14 and 17). Based on earlier observations around the WRV this SH was pretty widespread. A number of the slides that failed during the 1/27 storm cycle appear to have failed above the 12/11 interface. We don't have much direct data on these, but based on personal snowpack obs I suspect that some of these slides are failing on 1/12 and 1/27 SH (on shadies) and 1/27 MFcr+FCsf combos on solars. Due to time without snowfall and amount of solar input, 1/12 and 1/27 don't appear to be distinguishable on solars here.

My first ECT produced an ECTP2 on 12/11 with the entire block sliding into the pit but the other three failed on 1/12. CPST and PST cut lengths in the low to mid teens on 12/11, CPST and PST cut lengths in mid teens to low 20s on 1/12 SH.

Traveling up the slope where I dug, as I set the skin track I experienced no collapsing, which came as a bit of a surprise. I skied a lap, again feeling no collapsing (more difficult to detect on descent, of course). As I skinned back up I experienced 3 medium collapses and 1 large, rumbling collapse. As I toured along a ridgeline above a lot of "promising" looking N and NW facing paths I experienced some collapsing and was a bit surprised not to trigger any slides remotely. I didn't have to wait too long though. Above a wind-loaded, NNE facing path at 9,000' I felt a sizable collapse and watched as a 100-150' wide chunk of the slope below we fractured and slid. In some areas, it slid near the ground (12/11?) and in others a bit higher in the pack (1/12 or 1/27). As the slide reached the end of its path (1,000' vert) it sympathetically triggered 3 or 4 D2 size pockets up to 0.5 miles away.