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Wind Slab Fracture, Powder Bowl

Location Name: 
Green Butte, Powder Bowl, Lower Sun Bowl
Region: 
Mt. Shasta
Date and time of observation: 
Sun, 12/25/2016 - 8:30am
Observation made by: 
Forecaster
Red Flags:
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain

Location Map

United States
41° 21' 55.2348" N, 122° 12' 59.346" W
See map: Google Maps
US

Snowpack Observations

Details

Photo taken on Green Butte Ridge looking into Southeast slopes of Powder Bowl at 8,800ft.  Wind slab fracture occurred from the weight of a skier.  The slab arrested and no avalanche occurred.  This is an obvious sign of instability.  Wind slabs exist in leeward terrain above treeline and have the potential to be human triggered.

A test pit dug on a Southeast slope in lower Sun Bowl near treeline at 8,000ft indicated that the storm snow is bonding well to the old snow surface .  No propagation occurred in large column tests, and small column tests showed resistant planar fractures.   

ECTN 15 down 35cm x 2

CT 12 down 35cm RP

Photos

Weather Observations

Details

Sunny, cold, and calm winds below 9,000ft

Statistics

Cloud Cover: 
Clear
Blowing Snow: 
Yes
Air temperature: 
Below Freezing
Air temperature trend: 
Static
Wind Speed: 
Light
Wind Direction: 
Northwest