Date of Observation: 03/31/2022
Name: Evan Ross
Zone: Northwest Mountains
Route Description: Ruby Range near Irwin
Observed avalanche activity: Yes
Avalanches: The Ruby Range had a good natural avalanche cycle yesterday. Wind slabs had failed on north to east to south-facing slopes, mostly above treeline. The crowns were generally shallow, but some had fairly wide propagation through the start zones. Most avalanches appeared to be on the lowest end of a D2.
There were several D1 loose wet avalanches on easterly and south easterly facing slopes that ran today.
Weather: Clear and calm. Cloud cover quickly increased around just after noon.
Snowpack: Traveled on a number of steep, small terrain features on NE to E to SE between 10,500 and 12,400ft with only 1 notable result. Dug into several different slopes looking at the recent storm snow down to the 3/29 interface. The snowpack structure was fairly simple and could be summarized similarly for all those locations. The recent storm snow has a notable density change with stronger snow over softer snow. In some areas, it’s just a thin layer of softer precipitation particles near the 3/29 interface and in others, it’s layers of graupel. While we did find a notable layer of faceted grains at the 3/29 interface yesterday on a north-facing slope, I wasn’t able to find any notable persistent weak layers above the 3/29 interface in today’s observation. ECT test didn’t produce results and CT test produced moderate results on the density change with a rough fracture character. Slabs averaged in the 6 to 12 inch range, but I was able to find some wind drifted features with slabs near 2 feet thick.
Photos:
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[accordion_item title=”Avalanche Report #1″ parent_id=”my-accordion” open=”false”]Estimated avalanche date: 03/31/2022
Number of Avalanches: 4
Location
Location: Lake Irwin (Robinson Basin, Owen, Ruby)
Location Specific:
Start Zone Elevation: ATL: Above Tree Line
Aspect: SE
Characteristics
Trigger: Natural
Trigger modifier:
Type: Soft Slab
Failure Plane: Unknown
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: 2 South side of Ruby. 1 x South side of Owen. 1 x South side of Ruby.
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Estimated avalanche date: 03/31/2022
Number of Avalanches: 1
Location
Location: Lake Irwin (Robinson Basin, Owen, Ruby)
Location Specific:
Start Zone Elevation: ATL: Above Tree Line
Aspect: S
Characteristics
Trigger: Natural
Trigger modifier:
Type: Soft Slab
Failure Plane: Within storm 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: South Ruby
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[accordion_item title=”Avalanche Report #3″ parent_id=”my-accordion” open=”false”]
Estimated avalanche date: 03/31/2022
Number of Avalanches: 2
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: Soft Slab
Failure Plane: Within storm 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: NE to SE facing slopes between Purple and Owen.
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