Pro Field Report

Basic Information

Observation Details

Observation Date:
March 1, 2022
Submitted:
March 2, 2022
Observer:
SAC - VandenBos (off duty)
Zone or Region:
Banner Summit
Location:
Copper (6,900-8,900', most aspects except E)

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
None Experienced
Isolated cracking in fresh wind drifts.

Snow Stability

Stability Rating: 
Fair
Confidence in Rating: 
Low
Stability Trend: 
Steady

Media/Attachments

These slab avalanches failed on N/NE facing slopes at 8,400-8,700' near Banner Summit. Based on their location and the width of the crowns they likely failed on a layer of weak snow underneath. Across our forecast area, weak snow developed at the surface during January and February.
These slab avalanches failed on N/NE facing slopes at 8,300-8,500' near Banner Summit. Based on their location and the appearance of the crowns they likely failed on a layer of weak snow underneath. You can see that the bed surface has a grey/dark appearance to it, which is generally an indicator of faceted grains. Across our forecast area, weak snow developed at the surface during January and February.
These wet loose avalanches failed near Banner Summit on a N-facing slope at 8,200'. They likely failed during the day on 3/1, as the rain line climbed when rain was falling on new snow.

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Wind:
Moderate , SW
New/Recent Snowfall:
HST = 20-25cm dense snow

Afternoon wx obs: skies slightly clearing and precipitation easing, but plenty of drizzle at lower elevations and snow flurries at upper. Rain/snow line around 8,300-8,400'. Light to moderate winds out of the SW in middle and upper elevation terrain. HST = 20-25cm dense snow

Avalanche Observations

I observed numerous wet loose avalanches. I also observed several D1-D2 slab avalanches. Some failed in obviously wind-loaded locations, others were failing well below ridgelines in more sheltered terrain. I was able to intentionally trigger a D1 wet loose on a steep, rain-soaked slope at lower elevations at 1815 on my exit from the field.

Snowpack Observations

Primary objective was to get a sense for what the storm had done in this area and to see how the budding persistent slab problem was responding. And to hang out in the sog.
Storm: I found a very wet upper snowpack below 7,800', a bit of a transitional upper snowpack between 7,900' and 8,400', and a stark jump back into winter above 8,400'. Here, 20-25cm of dense (but dry) snow had accumulated. Rime feathers on trees up to 15cm long. It appeared that SW-W winds had blown steadily throughout the storm. I found stiff (1F+) slabs and drifts up to 40cm thick. The slabs I encountered were stubborn to unreactive, but I had no interest in encountering them in steeper, consequential terrain.
Persistent: As with our other zones, we have a budding persistent slab problem here. It may be starting to bloom. As is common around here, these problems tend to get buried more quickly in this zone so this area can be a good leading indicator for these problems. Visibility was generally poor, so my observations are limited. However, I did observe several slab avalanches that have some characteristics of persistent slab avalanches: they failed well below ridgelines in terrain sheltered from the wind, the bed surfaces had a telltale grey appearance that faceted grains often present, they had wide crowns. It is hard to have a ton of confidence about what happened with these slabs due to poor visibility and the complexity of the storm, but this problem has been in the back of my mind in this area for the past few weeks. Will be interesting to see what better visibility reveals in the coming days.

Avalanche Problems

Wind slabs, wet loose, and persistent slabs were all on my personal problem list.

Terrain Use

Keeping it simple due to snowpack complexity. Took a big step back over the past two days.