Avalanche Occurrence
General Information
Observer:
Professional
Verified by SAC?
Yes
Occurrence Date:
Jan 16, 2021 11:30 am (Exact)
Location:
Galena Summit, "SAC Class Knob"
Comments:
From the reporting party: At 11:30am, standing in a transition area, we felt a large collapse- this collapse propagated up the slope 250ft to the crown. HS at crown 90cm- Average depth of crown was 70cm failing on 12/11. Average depth of bed surface was 30cm. This avalanche was roughly 50ft wide and extended for 150ft . Obvious signs of cross loading from 1/13 wind event.
Avalanche Characteristics
# of Avys:
1Aspect:
E (E,SE)Start Zone Elev:
8800ftSize:
D1.5Type:
HS-Hard SlabTrigger:
AS-Skierr-Remote
Bed Surface:
O-Old SnowDepth:
2ftWidth:
50ftStart Zone Slope:
37°Weak Layer:
Dec 11, 2020 (FCsf)Comments:
From Ben’s investigation: Avalanche failed on small facets on top of melt-freeze crust that caps the December facets. The combination of warm ambient air temperatures and solar radiation immediately prior to the burial of this layer produced this crust. This crust+facet combo was very similar to the bed surface I observed on the Gladiator Creek natural avalanche I visited on 1/10.
Avalanche was 50' wide, ran about 100' along slope, and broke up to 2' deep. Bed surface angle ranged between 36-40*, primarily 37-38*. It failed just below the old toll road, where the slope was steepened by the building of the road.
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