Date of Observation: 01/26/2022
Name: Zach Guy and Jack Caprio
Zone: Northwest Mountains
Route Description: Traveled on various aspects on Mt. Owen and Mt. Afley near and above treeline
Observed avalanche activity: Yes
Avalanches: Ski triggered a handful of very thin wind slabs in a high elevation, northwest facing gulley. The slabs were 5 to 8 ft wide and a few inches thick. One entrained enough soft snow to knock someone over. Traveled through Silver Basin where there was long-running debris from ~3 very large avalanches that likely ran during the New Year’s Eve cycle. All three slides ran far into their runouts but didn’t appear to expand trim lines.
Weather: Cold temps, clear skies above an inversion cloud which burned off by late morning. Winds were blowing about 15 mph out of the northwest near summits, causing some light blowing snow.
Snowpack: 2″ or 3″ of very low density new snow. We rode on steep terrain on various aspects without signs of instability apart from some very thin pockets of wind slab near ridgetop. We traveled across several windward slopes near and above treeline (NW, W, and SW facing). The snowpack there is shallow and pretty weak. The snowpack is faceted throughout; you can easily sink a ski pole to the ground on all but the most heavily crossloaded features. Last Friday’s snow (1/25 interface) has faceted on most aspects (.5 mm, fist) or melted into a soft crust on southerly aspects. The 1/21 interface changes from a thick crust capping facets to a thin crust surrounded by facets to just weak facets as you move from SW to W aspects (see photo).
Photos:
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Blowing snow on the summit of Mt. Owen this morning
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Skier triggered a thin wind slab that entrained loose snow in this gulley.
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Near surface weak layers on SW to W aspects.
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Estimated runouts from 12/31 avalanche activity on the NW side of Owen and Purple. And debris from a small recent avalanche.
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Extensive debris below the west face of Afley, likely from 12/31 cycle. Viewed from afar and debris is getting smoothed over so red line is best guess at extent.
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Old deep slab near Blue Lake
Estimated avalanche date: 01/26/2022
Number of Avalanches: 1
Location
Location: Anthracite Creek (West side of Ruby Range, Marcellina)
Location Specific:
Start Zone Elevation: ATL: Above Tree Line
Aspect: NW
Characteristics
Trigger: Skier
Trigger modifier: Controlled
Type: Soft Slab
Failure Plane: Old snow
Size
Relative Size: R1 very small
Destructive Size: D1- Relatively harmless to people
Avg. crown height (inches):
Avg. width (feet): 8
Avg. vertical run (feet): 400
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments: NW side of Mt. Owen. Broke on 1/21 interface
Estimated avalanche date: 01/23/2022
Number of Avalanches: 1
Location
Location: Anthracite Creek (West side of Ruby Range, Marcellina)
Location Specific:
Start Zone Elevation: NTL: Near Tree Line
Aspect: NW
Characteristics
Trigger: Natural
Trigger modifier:
Type: Soft Slab
Failure Plane:
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: NW side of Owen. Unsure of exact failure date. Notable because debris looked a bit denser/harder than all of the other soft slabs we’ve seen. Almost a hard slab.
Estimated avalanche date: 12/31/2021
Number of Avalanches: 1
Location
Location: Anthracite Creek (West side of Ruby Range, Marcellina)
Location Specific:
Start Zone Elevation: ATL: Above Tree Line
Aspect: NW
Characteristics
Trigger: Natural
Trigger modifier:
Type: Hard Slab
Failure Plane: Old snow
Size
Relative Size: R4 large
Destructive Size: D3 – could destroy a car, wood-frame house, or snap trees
Avg. crown height (inches):
Avg. width (feet):
Avg. vertical run (feet):
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments: NW bowl of Purple/Owen. Snapped some trees.
Estimated avalanche date: 12/31/2021
Number of Avalanches: 1
Location
Location: Anthracite Creek (West side of Ruby Range, Marcellina)
Location Specific:
Start Zone Elevation: ATL: Above Tree Line
Aspect: W
Characteristics
Trigger: Natural
Trigger modifier:
Type: Unknown
Failure Plane:
Size
Relative Size:
Destructive Size: D3 – could destroy a car, wood-frame house, or snap trees
Avg. crown height (inches):
Avg. width (feet):
Avg. vertical run (feet):
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments: West face of Afley. Couldn’t see crown (probably blown over), debris ran far into runout.
Estimated avalanche date: 12/31/2021
Number of Avalanches: 1
Location
Location: Oh-Be-Joyful Basin
Location Specific:
Start Zone Elevation: ATL: Above Tree Line
Aspect: N
Characteristics
Trigger: Natural
Trigger modifier:
Type: Hard Slab
Failure Plane: Old snow
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: Below the cliffs above Blue Lake
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