Pro Field Report

Basic Information

Observation Details

Observation Date:
December 25, 2020
Submitted:
December 25, 2020
Observer:
SAC - Chris Lundy
Zone or Region:
Sawtooth and Western Smoky Mtns
Location:
Williams Peak Area (6400-9400', SE-E-NE)

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
None Experienced
Collapsing? 
None Experienced
A number of avalanches visible from the 12/21 cycle but nothing new.

Snow Stability

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

Bottom Line

Very weak facet layer remains widespread and buried around 16" deep. Although stability has improved since earlier in the week, poor snowpack test scores and scary layering are reminders that we're not out of the woods yet. Stability will likely deteriorate tonight into tomorrow as more snow comes our way.

Advanced Information

Weather Summary

Cloud Cover:
Partly Cloudy
Temperature:
cool
Wind:
Moderate , SW

Skies started out with few clouds this morning. High clouds increased through the day, and by later afternoon it was fully overcast. Ridgeline winds kicked in mid-afternoon and were moving small amounts of snow.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
30 Dec 21, 2020
(+/- 1 day) 		Northern Sawtooths
E ft 		D2 SS-Soft Slab N-Natural
Avalanche in the northern Sawtooths that released around December 21st. It fractured widely through complex alpine terrain.
Representative avalanches in Fishhook Creek. Avalanches occurred in the alpine as well as in the sheltered mid elevations (see left foreground).
Avalanches that released around December 21st. Note the smaller avalanches in the foreground that released in more sheltered, mid-elevation terrain.
Report
1 Dec 21, 2020
(+/- 1 day) 		The "X"
NE 9000ft 		D3 SS-Soft Slab N-Natural
Large avalanche that released around December 21st at the northern end of the Sawtooths. The avalanche broke nearly 1000' wide and ran 1.5-2' deep on a layer of facets.
Report
Northern Sawtooths
The "X"

Snowpack Observations

Little to no slab present at low elevations - still a junky mix of crusts and facets.

Snow depths at middle elevations average 85-115cm. Widespread rain crust to at least 9400' topped with 5-8cm of light snow; crust becomes thinner with elevation. Some faceting apparent beneath crust, but snow above crust didn't look particularly faceted.

12/11 FC layer is widespread - it seems to have strengthened slightly, but not by much - it's still F to maybe F+. The slab above it averages around 40cm thick at mid-elevations and is 4F in hardness.

@8400, E, 28*: HS 115cm. 12/11 45cm down (see pit below). ECTN20s x2 - which was surprising given how poor the structure was. PST33/100end.

@8800, E, 30*: HS 115cm. 12/11 40cm down. ECTP18 (see below). Very poor structure.

8400', E
8800', E. ECTP18 40cm down on 12/11 FC

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: 40cm
Weak Layer(s): Dec 11, 2020 (FCsf)

Terrain Use

I avoided consequential slopes steeper than 35 degrees.