Date of Observation: 12/08/2021
Name: Zach Guy
Zone: Northwest Mountains
Route Description: Quick morning tour in the Upper Slate, traveled on East to North facing aspects to 12,000 ft.
Observed avalanche activity: Yes
Avalanches: Skier triggered a few shallow wind slabs on crossloaded northeast aspects near and above treeline. Slabs were up to 10” thick, didn’t run far, and failed on the Dec 6 facet layer.
Weather: Light winds, clouds increased to overcast by 10 am. Very light snowfall started at 11 on our way out.
Snowpack: The few inches of Tuesday nights snow started faceting overnight, and is currently not bonded well to underlying melt freeze crusts. Thus, I expect aspects with a crusty 12/6 interface to be problematic with this incoming storm as well, at least in the short term. Shady aspects are already demonstrating their poor bonding to 12/6 with easily triggered pockets and cracking anywhere that there’s been enough wind transport for slab formation.
Photos:
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Southerly facing terrain that was mostly dirt prior to a few inches on Tuesday night
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Small wind slab triggered on a cross drifted terrain feature. NE aspect NTL
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Small wind slab triggered on a cross drifted terrain feature. NE aspect NTL
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Hand pit on north aspect above treeline
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Estimated avalanche date: 12/08/2021
Number of Avalanches: 2
Location
Location: Upper Slate (Purple, Yule Pass, Paradise Divide)
Location Specific:
Start Zone Elevation: NTL: Near Tree Line
Aspect: NE
Characteristics
Trigger: Skier
Trigger modifier: Controlled
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): 8
Avg. width (feet): 20
Avg. vertical run (feet): 50
Involvements
# of people caught:
# of partial burials:
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Additional comments:
Estimated avalanche date: 12/08/2021
Number of Avalanches: 1
Location
Location: Upper Slate (Purple, Yule Pass, Paradise Divide)
Location Specific:
Start Zone Elevation: ATL: Above Tree Line
Aspect: NE
Characteristics
Trigger: Skier
Trigger modifier: Controlled
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): 10
Avg. width (feet): 8
Avg. vertical run (feet): 30
Involvements
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