Wind slab on lower Trimmer

Location Name: 
Lower Trimmer Trees
Region: 
Luther Pass Area (including Job and Freel)
Observation Date & Time: 
Saturday, February 25, 2023 - 14:30
Location: 
38.882945, -119.947852
Is this an Avalanche Observation?: 
Yes


Conditions Alerts:


Terrain Alerts: 
Slopes Steeper than 30 degrees
Terrain Matches the Advisory

Observation made by: Public

Tabs

Observation
Description of Snow, Weather, and Avalanche Conditions: 

After skiing more moderate slope angle terrain on similar NW aspect and elevation without observing any signs of instability (no cracking or whumfing, no other avalanches, unconsolidated snow), we (party of 4) decided to investigate a steeper slope. We stopped at a safe spot to observe and make a plan for skiing the steeper face, planning to avoid the area of the slope to the skier's left with some small wind affected ridges visible in the snow. The steep face occurred at a convex rollover near a rock band. First skier traversed in a ski cut across the top of the slope toward snow that did not look as wind affected when the slab broke under their feet. Skier was able to continue skiing out of the slab and stopped at a safe place while the slab ran behind them. The rest of the party was able to traverse high without entering the steep face. The crown was probably a foot deep at its tallest, average depth 6 inches, and propagated farther left and down the slope than expected given how dry and loose it seemed. Probably unlikely to bury anyone, but could have knocked a skiier off their feet and pushed them into a tree or treewell, as the debri/run out continued into the trees below. 

Hide Terrain Details
Terrain: elevations: 
Below Treeline
Terrain: aspects: 
NW
Hide Avalanche Details
Avalanche Type: 
Wind Slab
Failure Plane/Weak Layer: 
Unknown
Hide Trigger
Trigger: 
Skier
Trigger Modifier: 
Accidentally Triggered
Hide Terrain
Start Zone Slope Angle: 
38degrees
Aspect: 
Northwest
Starting Elevation: 
below-treeline
Hide Size
Crown Height: 
1 ft
Avalanche Width (Average width): 
35ft.
Avalanche Length (Vertical Run): 
150ft.
Hide People Involved
Number of people caught: 
0
Number of partial burials: 
0
Number of full burials: 
0
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