Wind Slab Analysis, Jewel Basin, Swan Range

Location Name: 
Forecaster Observation - Jewel Basin, Swan Range
Region: 
Swan Range - West Side (Flathead Valley access)
Date and time of avalanche (best estimate if unknown): 
Thu, 11/30/2017 - 12:00
Location Map: 


Red Flags: 
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain

Observation made by: Forecaster
Avalanche Observations
Avalanche Type: 
Slab
Trigger type: 
Natural
Aspect: 
East
Weak Layer: 
Within storm snow
Terrain: 
Near Treeline
Elevation: 
7 000ft.
Bed Surface: 
Other - explain below
More detailed information about the avalanche: 

Evidence of a couple, isolated natural wind slabs that failed above 7000' at some point during our last storm. All were D1, R1 and confined to the new snow sitting ontop of the Thanksgiving rain crust. Observed minor cracking to surface snow while traversing across the ridgeline separating Noisy and Jewel Basin's. Wind protected areas did not show signs of deep or dense wind slab development. Thanksgiving rain crust was stout ranging from 8 to 15 inches thick with 4 to 6 inches of new snow on top. Old Halloween rain crust is showing signs of breaking down at elevations below 7000' where snowpack was saturated during our Thanksgiving rain event. Evidence of major wind transport with windward side of ridges being scoured down to ground vegetation while leeward side is holding over 3 feet of snow.

Snowpit or crown profile photo or graph: 
Avalanche Photos: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Light (Twigs in motion)
Precipitation: 
None
Air temperature trend: 
Static
Wind Direction: 
West
Accumulation rate: 
None
Activity: 
Skiing
Snowboarding