Pro Field Report

Basic Information

Observation Details

Observation Date:
January 14, 2020
Submitted:
January 14, 2020
Observer:
SAC - Martin Stefan
Zone or Region:
Galena Summit and Eastern Mtns
Location:
Prairie Peak

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
Isolated
Cracking and collapsing on wind affected snow, from mid elevation and up, not only confined to ridgeline.

Snow Stability

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

Bottom Line

In north facing terrain the buried weak layers from early december and New Year are buried 2-3' down at mid to high elevation. They give snappy results on stability tests, and I would not be surprised to see some big avalanches on these layers if the right trigger comes along.

Advanced Information

Weather Summary

Cloud Cover:
Mostly Cloudy
Temperature:
teens
Wind:
Moderate , SW

Coulds moved in and out, sometimes giving a good view into the Boulders. About 10cm of new snow since yesterday. Wind at high elevations mostly SW, but was swirling around quite a bit.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Comments Photo
1 Lightning pt, Boulders
S 10000'ish 		D2 U N-Natural Glassed from Hwy, low confidence in estimations. Looks like cross-loaded feature.
D2 avalanche on cross loaded feature on Lightning pt in the Boulders.

Snowpack Observations

Wind affected snow from mid elevations and up, even fairly sheltered meadows had a soft wind slab.

8400' ENE HS115
12/7@15cm FC/SH PST25/100(end)
12/31@55cm FC CPST30/100(end)
New storm slab @ 75cm (F - F+) ECTN no results on PST.
Snowpack below 12/31 in various degrees of faceting.

I would say the pit is fairly representative for mid to high elevation sheltered terrain, with a soft wind slab and reactive PWL:s.
On ridgeline wind from S had formed fresh drifts 50cm+ thick on P hard old windbuff with a few cm of soft DF in the interface. Lots of cracking and collapsing, but nothing bigger than a few meters.

Wind slab was present even at low elevations, but on top of a thin, faceted snow pack that was not reactive.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Wind Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Layer Depth/Date: 1/12, 30-50cm
Persistent Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
 Layer Depth/Date: 11/26, 12/7, 12/31 - 30-100cm
Comments: Problem is widespread, but sensitivity varies from unreative-reactive with wind loading and specifics of the PWL. I est. reactive in lightly wind loaded terrain open to the sky on N 1/4.

Terrain Use

I avoided avalanche terrain.