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Cornice Triggered Avalanche on Gray Butte
Location Name:
Gray ButteRegion:
Mt. ShastaDate and time of avalanche (best estimate if unknown):
Thu, 01/16/2020 - 2:30pmObservation made by:
ForecasterRed Flags:
Recent avalanche activity
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
Obvious avalanche path
Terrain Trap
Location Map
96067
Mount Shasta
, CA
United States
41° 20' 57.7176" N, 122° 11' 34.296" W
See map: Google Maps
California US
Avalanche Observations
Details
Photos
Characteristics
Avalanche Type:
SlabTrigger type:
Other - explain belowSlope:
35degreesAspect:
EastElevation:
8 000ft.Terrain:
Near TreelineWeak Layer:
Storm SnowBed Surface:
Old SnowCrown Height:
2 ftAvalanche Width:
600ft.Avalanche Length:
500ft.Number of people caught:
0Number of partial burials:
0Number of full burials:
0Weather Observations
Statistics
Cloud Cover:
100% of the sky covered by cloudsBlowing Snow:
YesPrecipitation:
SnowAccumulation rate:
Less than 1 in. per hourAir temperature:
Below FreezingAir temperature trend:
StaticWind Speed:
LightWind Direction:
Southwest
1-16-20 - Gray Butte 8,000 ft - Near Treeline - East Bowl
An intentional cornice triggered storm slab avalanche occurred today near treeline, off the top of Gray Butte, east facing. Cornices were easily triggered onto slopes below and released this avalanche, though not right away, indicating a mid-slope trigger. The crown was an average of 2 feet deep and at least 600 feet wide. Poor visibility limited full view. The avalanche failed on several weak layers including the new snow/old snow interface as well as within the new snow. New snow totals range from 20 to 30 inches.
Nearly all the red flags of avalanche danger were present today. Woomphing sounds were heard many times up the south side of Gray Butte. Shooting cracks were observed within fresh wind slabs near and above treeline. Ski cuts produced propagating soft storm slabs below treeline within the top 6-8 inches of new snow on small test slopes. Based on the many neon flashing signs mother nature provided, we played it very conservative with our terrain choice.