Avalanche on Maggies

Location Name: 
Maggies Peak
Region: 
Desolation Wilderness Area (including Emerald Bay)
Date and time of avalanche (best estimate if unknown): 
Tue, 02/16/2010 - 10:30
Location Map: 
United States
38° 55' 52.1652" N, 120° 6' 46.5768" W
See map: Google Maps
US


Red Flags: 
Rapid warming
Obvious avalanche path
Observation made by: Professional Observer
Avalanche Observations
Avalanche Type: 
wet,loose,
Slope: 
35degrees
Trigger type: 
Skier
Aspect: 
Southeast
Weak Layer: 
Old Snow
Avalanche Width: 
10ft.
Terrain: 
Below Treeline
Elevation: 
8 100ft.
Bed Surface: 
Old Snow
Avalanche Length: 
500ft.
More detailed information about the avalanche: 

At 10am skiers R of Treth's still held winter snow that sluffed easily and entrained wet snow in the middle of the chute. Skiers L was corn snow that had set-up well overnight, but by 10am was already wet. Both aspects consistently released loose snow that entrained more snow in the crux, where terrain narrows to 6-10ft wide.

 

Snowpack above the crux, both skiers R and L, was loose dry and loose wet respectively, over a supportive layer 10-20cm below the surface. This supportive layer acted as the bed surface from the crux and below.

 

Mitt pits below the crux (8000ft) showed a half-step in hand hardness from the surface snow to the supportive layer. Wet snow from surface to ground. Heat traps (bushes, rocks) minimized the supportive layer and deep ski pen in these areas made skiing challenging.

 

The pictured avalanche appears to have taken place yesterday under similar snow and weather conditions. Human triggered, but likely a slow - mover and limited to a D1+ given the lack of terrain traps below the crux.

Avalanche Photos: 
Weather Observations
Air temperature: 
Above Freezing
Precipitation: 
Air temperature trend: 
Warming
Wind Direction: 
Accumulation rate: 
More detailed information about the weather: 

Clear views from atop Maggies into Desolation area showed no evidence of natural avalanches from yesterday's warm weather. Very warm temps today by 10am at 8500ft.