Pro Field Report

Basic Information

Observation Details

Observation Date:
January 9, 2022
Submitted:
January 10, 2022
Observer:
SAC - VandenBos, VandenBos (off duty)
Zone or Region:
Sawtooth and Western Smoky Mtns
Location:
Fishhook (6,500-10,000', N-NE-E-SE-S)

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
None Experienced
Limited cracking in fresh drifts on steep slopes.

Snow Stability

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

Media/Attachments

Recent loose snow and slab avalanches at the head of the Fishhook drainage.
Crown of large avalanche that failed on a S-SE facing slope above the Fishhook drainage at the tail end of the recent storm.
Crown of a large avalanche that failed above the Fishhook drainage near the tail end of the recent storm.
This very large avalanche was triggered by the failure of a massive cornice from above. The crown looks quite deep in places, this may have failed on October snow buried at the base of the snowpack.
This large avalanche was triggered by the failure of a massive cornice from above. The crown looks quite deep in places, this may have failed on October snow buried at the base of the snowpack.
This avalanche failed at the head of the Fishhook drainage in the Sawtooths during the recent storm. The crown spans nearly 1/4 mile of terrain.
This very large avalanche was triggered by the failure of a massive cornice from above. The crown looks quite deep in places, this may have failed on October snow buried at the base of the snowpack.

Advanced Information

Weather Summary

Cloud Cover:
Mostly Sunny
Wind:
Light , NW

Strong temperature inversion in the morning. This partially mixed out during the day but remained present throughout. Calm to light winds out of the south half of the compass.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
1 Jan 6, 2022
(+/- 1 day) 		Fishhook
SE 9000ft 		D2 N-Natural
Crown of a large avalanche that failed above the Fishhook drainage near the tail end of the recent storm.
Report
1 Jan 6, 2022
(+/- 1 day) 		Fishhook
E 9600ft 		D2.5 N-Natural
This very large avalanche was triggered by the failure of a massive cornice from above. The crown looks quite deep in places, this may have failed on October snow buried at the base of the snowpack.
This large avalanche was triggered by the failure of a massive cornice from above. The crown looks quite deep in places, this may have failed on October snow buried at the base of the snowpack.
Report
1 Jan 6, 2022
(+/- 1 day) 		White Spider
SE 9700ft 		D2 N-Natural
Crown of large avalanche that failed on a S-SE facing slope above the Fishhook drainage at the tail end of the recent storm.
Report
1 Jan 6, 2022
(+/- 1 day) 		Ebert-Baron ridge
E 9750ft 		D3 N-Natural Report
2 Jan 5, 2022
(+/- 1 day) 		Fishhook
N 8500ft 		D2.5 N-Natural Report
Fishhook
Fishhook
White Spider
Ebert-Baron ridge
Fishhook

Pattern of observed avalanche activity continues to indicate that 1/3 FC+MFcr is a problem. Large, deep crown triggered by cornice may have failed on 12/11, pretty hard to have any certainty on that.

Snowpack Observations

Dug down to our old friend 12/11 to see what was happening down there. N facing slope at 7,900'. DH is still dry and lacking hardness (4F-) but grains are starting to look better (losing striations and edges on cups, DHxr). Attempted one CPST on this but failed to completely isolate the block and results were inconclusive. When I pried on the back of the block there was a loud pop and the block dropped a few cms into the facets below. The upper portion of 12/11 remained attached to the block. I pried the block until it fell on the pit floor, then stood on top of it to do tests in the upper snowpack. Boot pen 1-3 cm.
The majority of the overlying slab is P or harder. Shovel shears and ECTs in this location produced rough shears and non-propagating results. We encountered thin, unreactive to stubborn wind slabs in alpine terrain.

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
Persistent Slab
Isolated
Specific
Widespread
 Unknown
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Weak Layer(s): Jan 3, 2022 (MFcr)
Comments: Rose shaded based on observations of this layer in other zones and pattern of recent avalanche activity across the region.
Deep Persistent Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Weak Layer(s): Dec 11, 2021 (FC)

Hard to order problems 1 and 2. I'm currently avoiding terrain where 1/3 is present as a facet+crust combination.

Terrain Use

Terrain selection was driven by the presence of 1/3 and 12/19-24 MFcr+FC combos and by the presence and character of upper snowpack wind slabs. Continuing to avoid the type of terrain where encountering a 12/11 problem is a remote possibility (very steep, rocky, wind hammered, open alpine faces).