Swans need to migrate with that kind of crust

Location Name: 
Forecaster Observation - Central Swan
Observation date: 
Thursday, January 2, 2020 - 17:00

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

Tabs

Quick Observation

Today we traveled in the Swan Range to hunt down natural activity from the storm. We also wanted to see if we could locate any preserved surface hoar or near surface facets buried near the rain crust that occurred on December 31. In the area we rode, we found one small storm slab, a thin layer of facets near the December 31 crust, and no surface hoar. We also found a deep snowpack (relative to other areas in our region) with 12 to 16 inches of inverted new snow.

- Snowpit at 6300' NW aspect ECTPV (propagated during isolation). 

- Other hand pits sheared during isolation. 

- No cracking, collapsing, and test slopes did not produce avalanches with both ski and snowmobile. 

- Snowpack is getting deeper! Like 6 feet deep.  

Our terrain choices became narrowed as we entered into a thick cloud with low visibility. Given this, we did not feel comfortable being out of sight from one another with the mixed messages the snowpack was sending us. Low and behold the sun hit the peaks when we got back to the truck. We should have gone out to breakfast beforehand. 

Snowpack, Avalanche, Weather Images: 
Snowpack, Avalanche, Weather Videos: 

January 2nd Swan Range

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
NE
E
S
SW
W
Red Flags: 
Blowing snow
Total Snow Depth: 
185
More comments about the snowpack and weather: 
With no cracking, collapsing and one small avalanche, we felt that the test pit results were sending us false unstable messages. We added into our bank of information and still played it conservatively. Rain crust was up to 1 cm thick at 6500 feet. Skiing down it made an audible snap during a few turns. Facets around rain crust was thin. No evidence of surface hoar in pits dug at mid-elevations valley floor, or pits dug on NE and SW aspects above 6500'. Sky cover went from overcast->obscured->broken throughout the day.
Blowing Snow: 
Light
Wind Speed: 
Moderate (Small trees sway)
Wind Direction: 
Southwest
Air temperature: 
Below Freezing
Sky Cover: 
Obscured by fog, etc (X)
Highest Precipitation Rate: 
Very Light Snowfall (S-1)
Avalanche Details
Avalanche Details: 
Date and Time of Avalanche: 
Wednesday, January 1, 2020 - 08:00
Number of avalanches: 
1
Avalanche Type: 
Soft Slab
Failure Plane/Weak Layer: 
Unknown
Hide Trigger
Trigger: 
natural
Trigger Modifier: 
Cornice Fall Triggered
Hide Terrain
Start Zone Slope Angle: 
40
Aspect: 
Northeast
Starting Elevation: 
near-treeline
Hide Size
Destructive Size: 
D1 Relatively harmless to people.
Relative Size: 
R2 Small
Crown Height: 
Less than 1 ft
Avalanche Length (Vertical Run): 
200ft.
Avalanche Width (Average width): 
50ft.