Date of Observation: 12/12/2021
Name: Zach Guy
Zone: Southeast/Northwest Mountains boundary
Route Description: Mount Emmons. Traveled mostly on S and SE aspects to 12,400′
Observed avalanche activity: Yes
Avalanches: Adding a pile of previously undocumented naturals to the list from the recent cycle that fit the pattern of what we’ve been observing, see photos and details below. Most of the northeast side of Red Lady Bowl appeared to run and there were a handful of wind slabs that ran on the southeast portion of the bowl. I didn’t see any fresh avalanches from the past 24 hours.
Weather: Sunny, clear. Winds were strong enough to blow my #tired hat off my head, but luckily I retrieved it. Snow transport continues above treeline in exposed locations.
Snowpack: Our field objective today was to assess if the persistent slab problem should expand to the sunny aspects that held a crust (rather than dirt) before the storm. In short, I didn’t find evidence of persisting issues on the 12/6 crust where it is stout on sunny aspects. In a pit on a SE aspect NTL, long column tests produced no concerning results on the crust. The crust is pencil hard and goes to the ground where we dug. Above the crust, there are .3 to .5 mm rounding facets, 4F- (the 12/8 layer).
We traveled mostly on sunny slopes that were dirt before the storm with no signs of instability. As soon as we scooted into some low angle, shady terrain below treeline, we started getting collapses that would radiate to the nearest cluster of trees. These same slopes are developing small grained surface hoar and near-surface facets on the snow surface right now. Kicked at a few recent drifts at higher elevations with minimal cracking.
Photos:
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Hasty pit on SE aspect NTL of Mt. Emmons
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On going wind loading at the summit of Red Lady
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A few small crowns in Redwell Basin
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Crowns in Elk Creek and Evans Basin
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Crowns and debris in Red Lady Bowl
Estimated avalanche date: 12/10/2021
Number of Avalanches: 3
Location
Location: Mount Emmons
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: 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: Evans and Elk Creek Basin
Estimated avalanche date: 12/10/2021
Number of Avalanches: 2
Location
Location: Mount Emmons
Location Specific:
Start Zone Elevation: BTL: Below Tree Line
Aspect: E
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):
Avg. width (feet):
Avg. vertical run (feet):
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments: Elk Creek
Estimated avalanche date: 12/10/2021
Number of Avalanches: 2
Location
Location: Mount Emmons
Location Specific:
Start Zone Elevation: ATL: Above Tree Line
Aspect: NE
Characteristics
Trigger: Natural
Trigger modifier:
Type: Soft Slab
Failure Plane:
Size
Relative Size: R1 very 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: Redwell Basin
Estimated avalanche date: 12/09/2021
Number of Avalanches: 4
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: Unknown
Size
Relative Size: R1 very 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: Red Lady Bowl. Unknown if these were individual events or one wider connected slab. Crown is now drifted in in many places.
Estimated avalanche date: 12/10/2021
Number of Avalanches: 2
Location
Location: Mount Emmons
Location Specific:
Start Zone Elevation: ATL: Above Tree Line
Aspect: SE
Characteristics
Trigger: Natural
Trigger modifier:
Type: Soft Slab
Failure Plane:
Size
Relative Size: R1 very 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: Red Lady Bowl
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