Winter Up High

Location Name: 
Forecaster Observation - Swan Range
Observation date: 
Wednesday, December 8, 2021 - 18:45

Is this an Avalanche Observation: 
Yes
Observation made by: Forecaster

Tabs

Quick Observation

It was a stormy winter's day as we wandered around the Noisy and Jewel Basins - at least once we got above about 4,500 feet.

  • We got rained on up to 4,500 feet in the morning and the snow line seemed to never have dipped below that. We rode our sleds on the road on thin slushy ice until that elevation on the way in, and on the way out.
  • Above 5,000 feet precip definitely changed to all snow. 
  • New snow was being blown by moderate to strong southwest winds above about 7,000 feet. There was limited snow avaliable for building wind slabs, however. A rain crust capped all but the top 2 to 4 inches of the snowpack. We only got minor cracking on leeward slopes.
  • We saw one small, older natural wind slab avalanche on a steep northeast facing slope. We guessed had failed during the last storm on the 4th.
  • We looking at the snowpack on northeasterly slopes at 6,000 and 7,000 feet. We found a few distinctive weak layers below stout crusts and hard slabs. 
  • Snowfall diminished by mid afternoon. It had snowed 2 inches on our sleds when we returned to Camp Misery.

Skiing was sporty on both east and west aspects. Early season bush is still poking throught the surface and that rain crust  just below the soft new snow can catch you up.

Snowpack, Avalanche, Weather Images: 
Travel Details
Region: 
Swan Range - West Side (Flathead Valley access)
Route Description: 
Activity: 
Skiing
Snowmobiling
Snowpack Details
Snowpack and Weather Details: 
Hide Terrain
Elevation of observation: 
3500-5000 ft
5000-6500 ft
Above 6500 ft
Aspect(s) of observation: 
N
NE
S
SW
W
NW
Red Flags: 
Blowing snow
Persistent Weak Layers: 
Facets or Faceted Crust
Buried
New Snow in the past 24 hours: 
4.00in.
Total Snow Depth: 
90 cm
More comments about the snowpack and weather: 
Average HS on windward and solar slopes: 35cm. Rain crust found at all aspects/elevations with average of 5cm on top. See snow profiles.
Blowing Snow: 
Moderate
Wind Speed: 
Moderate (Small trees sway)
Wind Direction: 
Southwest
Air temperature: 
Below Freezing
Snow line: 
4500 feet
Sky Cover: 
Obscured by fog, etc (X)
Highest Precipitation Rate: 
Moderate Snowfall (S2)
Avalanche Details
Avalanche Details: 
Date and Time of Avalanche: 
Saturday, December 4, 2021 - 12:00
Number of avalanches: 
1
Avalanche Type: 
Soft Slab
Failure Plane/Weak Layer: 
Within storm snow
More information or comments about the avalanche: 
Hide Trigger
Trigger: 
natural
Hide Terrain
Start Zone Slope Angle: 
40
Aspect: 
Northeast
Starting Elevation: 
above-treeline
Hide Size
Destructive Size: 
D1 Relatively harmless to people.
Crown Height: 
Less than 1 ft
Avalanche Width (Average width): 
30ft.
Avalanche Location: