Pro Field Report

Basic Information

Observation Details

Observation Date:
December 15, 2022
Submitted:
December 15, 2022
Observer:
SAC - Jon Preuss
Zone or Region:
Galena Summit and Eastern Mtns
Location:
Prairie Peak (E-S-N; 7000-9483')

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
None Experienced
Collapsing? 
Isolated
Heard collapses on 11/27 layer down in lower elevations.

Snow Stability

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

Bottom Line

A weak layer of sugary facets is sitting on top of a crust layer buried 1-2 foot down. Recent natural avalanches have proved these south facing aspects to be suspect. Shady slopes have a worse looking layout and a weak layer getting buried further into the snowpack. Keeping away from avalanche terrain remains the only solution to such a widespread problem.

Advanced Information

Weather Summary

Cloud Cover:
Mostly Cloudy
Wind:
Light , NW
New/Recent Snowfall:
HN: 3cm, HST: 50cm

Cirrus clouds moved out of the area after 1300. There was lots of sunshine in the afternoon hours with light winds.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
3 Dec 11, 2022
(+/- 1 day) 		Cherry Creek
W 10300ft 		D2 HS-Hard Slab N-Natural Report
File
Cherry Creek
 #  Date Location Size Type Bed Sfc Depth Trigger Comments Photo
2 West Fork Prairie Creek
SE 9300' 		D2 SS I-New/Old Interface 1-2' N-Natural
2 Cherry Creek
W 10,300' 		D2 U I-New/Old Interface N-Natural There is also an old avalanche that may have failed during the beginning of the storm on a SW aspect at 10,200' in the middle bowl of this photo.
4 Mill Creek
W 9600' 		D2 SS N-Natural None

The West Fork Prairie Creek naturals confirmed there is an instability on some south facing aspects. My snowpits today confirmed it was likely failing on the new/old interface of 12/8.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Persistent Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Layer Depth/Date: 50-90cm

The southerly facing avalanches observed appear to have failed on the 12/8 layer buried ~50cm down. There is certainly less avalanche activity occurring on south slopes, but that doesn't make them any more appealing to hop on right now. The W-N-E avalanches could be failing on either of the past weak layers (11/27 and 12/8) depending on the grain type and/or size. It is challenging to tell from the crown depths being far away. If there was surface hoar present in the recent n/o, I would imagine that to fail easier than the deeper layer (11/27). In this area, the deeper layer (11/27) was more concerning because of the poor structure and lack of a reactive n/o layer. The 11/27 layer is pushing 90cm deep with a beefy slab on top of it.

Terrain Use

Closed avalanche terrain and was mindful of remote triggering slopes above.