Wind Slabs and Cornice Collapse on Tamarack

Location Name: 
Hourglass
Region: 
Mount Rose Area
Date and time of avalanche (best estimate if unknown): 
Fri, 04/14/2017 - 09:30
Location Map: 
United States
39° 19' 9.3072" N, 119° 55' 20.1072" W
See map: Google Maps
US


Red Flags: 
Recent avalanche activity
Recent loading by new snow, wind, or rain
Rapid warming
Obvious avalanche path
Observation made by: Forecaster
Avalanche Observations
Avalanche Type: 
Slab
Trigger type: 
Unknown
Crown Height: 
1 ft
Aspect: 
Northeast
Weak Layer: 
Unknown
Avalanche Width: 
100ft.
Terrain: 
Above Treeline
Elevation: 
9 840ft.
Bed Surface: 
Unknown
Avalanche Length: 
600ft.
Number of similar avalanches: 
3
More detailed information about the avalanche: 

We noticed at least 3 wind slab avalanches on Tamarack Peak from the summit of the Fireplug. One underneath the cornice above the Hourglass; one under the cornice on the far east ridge of Tamarack; and one smaller one under a cornice on the ridge above the Gasex pipes. We could not tell exactly how deep these slides were, nor exactly what triggered them although it was likely pieces of cornice falling onto the wind-loaded slopes. We also could not determine exactly when these avalanches occurred, but the one on the Hourglass did overrun some fresh ski tracks in the bowl so it must have occurred after it stopped snowing and after people had time to ski the slope. This slide likely occurred in the mid-morning hours today based on that information. It is possible but uncertain that sun and rapid warming could have caused the cornices to weaken and fail. 

Avalanche Photos: