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Natural and skier triggered avalanches on Gray Butte

Location Name: 
Gray Butte
Region: 
Mt. Shasta
Date and time of avalanche (best estimate if unknown): 
Sun, 01/06/2019 - 2:30pm
Observation made by: 
Forecaster
Red Flags: 
Recent loading by new snow, wind, or rainObvious avalanche path

Location Map

96067 Mount Shasta , CA
United States
41° 20' 44.7756" N, 122° 11' 47.6016" W
California US

Avalanche Observations

Details

A crown line from a natural storm slab avalanche was observed while skiing off the west/northwest facing aspect of Gray Butte, down from the radio towers and through the big trees. About half way down, the slope rolls over and opens up. This avalanche starting zone/path is a frequent flyer. The avalanche had failed at the old snow/new snow interface and was about 1 to 1.5 feet deep and had likely occurred within the last 1-3 hours. While skiing on adjacent slopes, additional small storm slab avalanches were easily triggered on the same layer. Both natural and human triggered avalanches were big enough to bury, injure or kill a person, especially with thick trees below exacerbating consequences.

Characteristics

Avalanche Type: 
Slab
Trigger type: 
Natural
Slope: 
38degrees
Aspect: 
Northwest
Elevation: 
7 500ft.
Terrain: 
Near Treeline
Weak Layer: 
Storm Snow
Bed Surface: 
Old Snow
Crown Height: 
1 ft
Avalanche Width: 
150ft.
Avalanche Length: 
600ft.
Number of similar avalanches: 
1
Number of people caught: 
0
Number of partial burials: 
0
Number of full burials: 
0

Weather Observations

Details

A strong winter storm has impacted the area all weekend. Saturday, upwards of a foot of snow fell. Snowfall began in earnest on Sunday (today) and greater than 1 inch an hour of low density snow accumulation was observed for most of the day. Winds were gusty at times but surprisingly absent with little effect on snowpack below and near treeline on Gray Butte. 

Statistics

Cloud Cover: 
100% of the sky covered by clouds
Blowing Snow: 
Yes
Precipitation: 
Snow
Accumulation rate: 
Greater than 1 in. per hour
Air temperature: 
Below Freezing
Air temperature trend: 
Static
Wind Speed: 
Light
Wind Direction: 
Southwest