Date of Observation: 12/29/2022
Name: Zach Guy
Zone: Southeast Mountains
Route Description: Rec tour on Anthracite Mesa, traveling on various aspects to 10,800′
Observed avalanche activity: Yes
Avalanches: Large natural slab avalanche likely ran this morning on a southwest facing slope of Gothic, to the ground. Skier triggered a couple of thin soft slabs that failed within the storm snow on lightly cross-drifted southerly terrain. Had decent vis of the Lower Slate from Birthday Bowl on Skooks to Happy Chutes and only saw a handful of loose dry avalanches.
Weather: Very light snowfall. Light winds with occasional moderate gusts causing brief periods of blowing snow. Cold temps.
Snowpack: 35 to 40 cm of F to F+ snow down to our most recent facet (1mm) and crust/facet layers. This interface produced only minor cracking and non-propagating results in quick tests. No signs of buried surface hoar here. In lightly wind-drifted terrain exposed to down valley winds, we produced shooting cracks and triggered a couple of soft slabs breaking on precip particles within the storm snow, up to 25 cm thick or so. One was remotely triggered from 20 meters away.
Photos:
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Natural slab avalanche on SW side of Gothic exposed ground.
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Skier triggered soft slab on a lightly drifted slope.
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Skier triggered soft slab on a lightly drifted slope.
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Some kind of strange wild donkey hunkering down before the next storm.
Estimated avalanche date: 12/29/2022
Number of Avalanches: 1
Location
Location: Gothic Mountain
Location Specific:
Start Zone Elevation: ATL: Above Tree Line
Aspect: SW
Characteristics
Trigger: Natural
Trigger modifier:
Type: Soft Slab
Failure Plane: Ground
Size
Relative Size: R2 small
Destructive Size: D2 – could bury, injure, or kill a person
Avg. crown height (inches):
Avg. width (feet):
Avg. vertical run (feet):
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments: Base of slab may have been hard slab. Seen from a distance in flat light.
Estimated avalanche date: 12/29/2022
Number of Avalanches: 1
Location
Location: Other: Add text
Location Specific:
Start Zone Elevation: BTL: Below Tree Line
Aspect: S
Characteristics
Trigger: Skier
Trigger modifier: Remote
Type: Soft Slab
Failure Plane: Within storm snow
Size
Relative Size: R1 very small
Destructive Size: D1.5
Avg. crown height (inches): 8
Avg. width (feet): 50
Avg. vertical run (feet):
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments: Anthracite Mesa above Slate.
Estimated avalanche date: 12/29/2022
Number of Avalanches: 1
Location
Location: Other: Add text
Location Specific:
Start Zone Elevation: BTL: Below Tree Line
Aspect: SW
Characteristics
Trigger: Skier
Trigger modifier:
Type: Soft Slab
Failure Plane: Within storm snow
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: Anthracite Mesa above Slate.
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