Date of Observation: 01/13/2023
Name: Evan Ross
Zone: Northwest Mountains
Route Description: Ruby Range near Irwin. 11,000 to 13,000ft. NE-E-SE
Observed avalanche activity: Yes
Avalanches: 1 undocumented cornice avalanche on Mt Owen. Difficult to date, but probably early in the last storm. Fresh roller balls and tiny wet loose avalanches, primarily on SE-S-SW. Stayed up high all afternoon and didn’t get a good feel for wet avalanche activity at lower elevations.
Weather: Pleasant day in the alpine. Calm wind. High temps at Scarps ridge were just below freezing. High clouds created a partly cloudy sky
Snowpack: As expected, no obvious signs of instability. Managing old wind slabs, cornices, and sluffs were the primary avalanche problems encountered. We avoided areas with a below-average snowpack depth and southerly-facing slopes in the alpine. Snow surfaces were lovely. Even the wind effect was soft, a little thicker but still soft. Small SH on the snow surface all the way up at 13,000ft on ridgelines.
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Previously documented avalanches. The background is the Ant E Face. From this distance, those avalanches look soft and like they have a fair bit of snow-filled back in them. Perhaps releasing early in the last storm cycle starting 1/10.
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Looking down the Ruby Range.
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Roller balls on SW-facing slopes at 11,500ft in Robinson Basin
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Old Cornice Avalanche on Mt Owen.
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The start of an old Cornice avalanche on Mt Owen and other cornices hanging off the ridge.
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Estimated avalanche date: 01/10/2023
Number of Avalanches: 1
Location
Location: Lake Irwin (Robinson Basin, Owen, Ruby)
Location Specific:
Start Zone Elevation: ATL: Above Tree Line
Aspect: E
Characteristics
Trigger: Natural
Trigger modifier:
Type: Cornice
Failure Plane: Old snow
Size
Relative Size: R1 very 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: Cornice avalanche on Mt Owen. Ran fairly far and didn’t trigger any deeper avalanches on the slopes below the upper cliffs.
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