You've really got a hold on me

Location Name: 
Forecaster Observation - Swan Range
Observation date: 
Thursday, December 3, 2020 - 19:30
Is this an Avalanche Observation: 
Yes
Observation made by: Forecaster

Location

Tabs

Quick Observation

We visited the west side of the Swan Range to collect baseline snowpack data and observe the strong high-pressure impact gripping our region. I couldn't help but warble the Miracles 1962 Top 10 hit single, "You've really got a hold on me."

  • Solar warming initiated a couple of dozen loose snow slides on the steep west slopes of Great Northern and Mt Grant. One of these traveled 1000' and was D2 in size.
  • Inversions in the southern Flathead Valley resulted in low clouds and stagnant air. The northern Flathead Valley escaped these dreary conditions for at least another day.
  • Up to 9" of low-density surface snow survived today's warming on slopes sheltered from the sun and wind. This snow is faceting, losing strength, and around 5% density.
  • Surface snow moistened on slopes open to the sun. By day's end, some of these areas had developed a surface crust. 
  • The current weather is contributing to surface hoar development and surface faceting at all elevations and aspects. 
  • Despite the nearby Noisy Basin snotel reporting 109% of average snowpack, we were surprised at the thin snow cover on the sunny and windward aspects.

 

Snowpack, Avalanche, Weather Images: 
Travel Details
Region: 
Swan Range - West Side (Flathead Valley access)
Activity: 
Skiing
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
E
S
SW
W
NW
Red Flags: 
Avalanches from the past 2 days
Persistent Weak Layers: 
Surface Hoar
Facets or Faceted Crust
New Snow in the past 24 hours: 
0.00in.
Total Snow Depth: 
40"
More comments about the snowpack and weather: 
Snowpit at 6800' on an NW aspect. Snow depth=40". 2 faceted layers of concern. The first is 12" down below a crust (CT 17, ECTN18). The second is 30" down on top of the basal ice mass. We did not receive feedback on this layer during tests.
Wind Speed: 
Light (Twigs in motion)
Wind Direction: 
West
Air temperature: 
Below Freezing
Snow line: 
4000'
Sky Cover: 
Clear (CLR)
Avalanche Details
Avalanche Details: 
Date and Time of Avalanche: 
Thursday, December 3, 2020 - 14:00
Number of avalanches: 
20
Avalanche Type: 
Wet Loose
Failure Plane/Weak Layer: 
Unknown
More information or comments about the avalanche: 

Viewed from a distance. One D2 on Great Northern with the remainder D1-1.5 on Great Northern and Mt Grant. Slides initiated at both upper and mid-elevations.

Hide Trigger
Trigger: 
natural
Hide Terrain
Start Zone Slope Angle: 
40
Aspect: 
West
Starting Elevation: 
above-treeline
Hide Size
Destructive Size: 
D2 Could bury, injure, or kill a person.
Relative Size: 
R2 Small
Avalanche Length (Vertical Run): 
1000ft.
Avalanche Width (Average width): 
100ft.
Avalanche Location: