Date of Observation: 12/14/2021
Name: Eric Murrow
Zone: Southeast Mountains
Route Description: West Brush Creek road to skin up Union Chutes. Terrain south of WSC Peak in West Brush drainage, directly across valley from Teocalli.
Observed avalanche activity: Yes
Avalanches: Noticeably less avalanche activity below treeline as compared to Northwest Mountains forecast area. Near treeline produced numerous avalanches on north and northeast aspects directly below ridgeline in wind-drifted areas on shaded aspects.
Weather: Broken skies for much of the day with a pleasant period of Few clouds around 2 pm. Winds were light below treeline and looked to be moderate at ridgetop, but no wind loading was observed.
Snowpack: Small Surface Hoar was present near valley bottom but 100 feet above cold sink Surface Hoar disappeared. Snow surface on shaded aspects near and below treeline was faceted but small-grained (.5mm). Around 11,000 feet and above soft, breaker wind-board appeared across the landscape. I experienced many localized collapses, but just a single, loud moderately sized collapse as I exited a northeast-facing profile site (see attached image) which produced many cracks across the slope. I avoided steep, wind-drifted terrain in the area and stuck to simple, lower-angled options.
Snow depth on sunny slopes in the area was around 35cm and 70cm on shaded slopes. Ski penetration was generally around 6-8 inches and boot penetration was to the ground everywhere.
Photos:
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Test profile for northeast slope at 11,000 feet. As I exited the pit, I produced a loud-ish collapse that shot cracks up to 50 feet.
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This west-facing terrain near and above treeline has thin, but continuous coverage after last weeks stormy period.
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Example of some northeast-facing, near treeline terrain that shows thin, but fairly widespread slab formation across the landscape. I simply avoided this terrain and found safer options on sunnier slopes.
Estimated avalanche date: 12/10/2021
Number of Avalanches: 2
Location
Location: West Brush Creek
Location Specific:
Start Zone Elevation: NTL: Near Tree Line
Aspect: NE
Characteristics
Trigger: Natural
Trigger modifier:
Type: Soft Slab
Failure Plane:
Size
Relative Size: R1 very small
Destructive Size: D2 – could bury, injure, or kill a person
Avg. crown height (inches): 24
Avg. width (feet):
Avg. vertical run (feet):
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments: Only two D2’s I could see, but wind drifting may have obscured evidence. Did not see debris, but based on crown size and vertical run seemed to be on the smaller side of D2
Estimated avalanche date: 12/10/2021
Number of Avalanches: 3
Location
Location: West Brush Creek
Location Specific:
Start Zone Elevation: NTL: Near Tree Line
Aspect: NE
Characteristics
Trigger: Natural
Trigger modifier:
Type: Soft Slab
Failure Plane: New/Old interface
Size
Relative Size: R1 very small
Destructive Size: D1.5
Avg. crown height (inches): 24
Avg. width (feet):
Avg. vertical run (feet):
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments: Less wind-loaded areas. Could not see debris, but based on slope size these would not have buried a person unless terrain trappy.
Estimated avalanche date: 12/10/2021
Number of Avalanches: 2
Location
Location: West Brush Creek
Location Specific:
Start Zone Elevation: NTL: Near Tree Line
Aspect: N
Characteristics
Trigger: Natural
Trigger modifier:
Type: Soft Slab
Failure Plane: New/Old interface
Size
Relative Size: R1 very small
Destructive Size: D1.5
Avg. crown height (inches): 24
Avg. width (feet):
Avg. vertical run (feet):
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments: Less wind-drifted site. Could not see debris, but I doubt these would bury a person.
Estimated avalanche date: 12/10/2021
Number of Avalanches: 2
Location
Location: West Brush Creek
Location Specific:
Start Zone Elevation: BTL: Below Tree Line
Aspect: N
Characteristics
Trigger: Natural
Trigger modifier:
Type: Soft Slab
Failure Plane: New/Old interface
Size
Relative Size: R1 very small
Destructive Size: D1- Relatively harmless to people
Avg. crown height (inches):
Avg. width (feet):
Avg. vertical run (feet):
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments: Small north-facing avalanche below treeline. Convex rolls in steep terrain. Appeared to be the only two avalanches below treeline. No drifting involved, just high PI during the storm.
Estimated avalanche date:
Number of Avalanches:
Location
Location:
Location Specific:
Start Zone Elevation:
Aspect:
Characteristics
Trigger:
Trigger modifier:
Type:
Failure Plane:
Size
Relative Size:
Destructive Size:
Avg. crown height (inches):
Avg. width (feet):
Avg. vertical run (feet):
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments:
5099
