Date of Observation: 12/10/2021
Name: Zach Guy
Zone: Northwest Mountains
Route Description: Lower Slate, Lower Oh-Be-Joyful. Traveled on NE, SE, and S aspects to 10,700 ft.
Observed avalanche activity: Yes
Avalanches: Nearly every northerly facing avalanche slope that we were close enough to have good views of slid naturally overnight. Where we traveled, most of the terrain was relatively small and slides were D1 to D1.5, one D2. It appears most of Climax Chutes also ran, generally D1.5 to D2.
Weather: Light snowfall through most of the day, with a couple of brief pulses of moderate snowfall. Gusty northwest winds in the afternoon were blowing snow at all elevations. Cold temps.
Snowpack: Widespread collapsing on northerly aspects; some muffled, some rumbling. Shooting cracks on many slopes. The only steep terrain that we felt comfortable traveling on, and without signs of instability, were recent bed surfaces, low elevation southerlies (which were previously bare and without fresh drifting), and dense trees. About 2 to 3 feet of storm snow.
Did this cycle flush the basal facets? In the bedsurfaces that we traveled on, there was a crust or roughed up stiff layer on the sliding interface, with more weak facets below. Enough to provide some structure for modest loading, but I don’t think we’re out of the woods because there are still weak layers hanging on. Time will tell, but I think this cycle only shaved off the top half of our weak layer where we traveled.
Photos:
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Natural avalanche activity on Climax Chutes
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Natural avalanche activity on Climax Chutes
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Shooting cracks in small openings in the trees.
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Shooting cracks
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Shooting cracks
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Natural avalanche activity BTL
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Natural avalanche activity BTL
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Natural avalanche activity BTL
Estimated avalanche date: 12/09/2021
Number of Avalanches: 6
Location
Location: Schuylkill Ridge
Location Specific:
Start Zone Elevation: BTL: Below Tree Line
Aspect: NE
Characteristics
Trigger: Natural
Trigger modifier:
Type: Soft Slab
Failure Plane: New/Old interface
Size
Relative Size: R2 small
Destructive Size: D1.5
Avg. crown height (inches): 18
Avg. width (feet):
Avg. vertical run (feet):
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments: Ran sometime last night. About 5″ to 8″ on the bedsurface, generally.
Estimated avalanche date: 12/09/2021
Number of Avalanches: 2
Location
Location: Mount Emmons
Location Specific:
Start Zone Elevation: BTL: Below Tree Line
Aspect: NW
Characteristics
Trigger: Natural
Trigger modifier:
Type: Soft Slab
Failure Plane: New/Old interface
Size
Relative Size: R2 small
Destructive Size: D1.5
Avg. crown height (inches):
Avg. width (feet):
Avg. vertical run (feet):
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments:
Estimated avalanche date: 12/10/2021
Number of Avalanches: 2
Location
Location: Mount Emmons
Location Specific:
Start Zone Elevation: NTL: Near Tree Line
Aspect: E
Characteristics
Trigger: Natural
Trigger modifier:
Type: Soft Slab
Failure Plane:
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: Climax Chutes
Estimated avalanche date: 12/10/2021
Number of Avalanches: 2
Location
Location: Mount Emmons
Location Specific:
Start Zone Elevation: NTL: Near Tree Line
Aspect: NE
Characteristics
Trigger: Natural
Trigger modifier:
Type: Soft Slab
Failure Plane:
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:
Estimated avalanche date: 12/09/2021
Number of Avalanches: 1
Location
Location: Schuylkill Ridge
Location Specific:
Start Zone Elevation: BTL: Below Tree Line
Aspect: NE
Characteristics
Trigger: Natural
Trigger modifier:
Type: Soft Slab
Failure Plane: New/Old interface
Size
Relative Size: R2 small
Destructive Size: D2 – could bury, injure, or kill a person
Avg. crown height (inches): 18
Avg. width (feet):
Avg. vertical run (feet):
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments:
5068