Hair raising collapses

Location Name: 
Southern Whitefish Range
Observation date: 
Thursday, December 12, 2019 - 16:45
Is this an Avalanche Observation: 
No
Observation made by: Forecaster

Tabs

Quick Observation

Today's travel in the Southern Whitefish Range highlighted how ripe the conditions are for human triggered avalanches. We were feeling booming collapses on almost all aspects throughout our travels. The decision was easy to keep slope angles low after a collapse that sent a ~150' shooting crack above us. We skied on slopes in the low 30-degree range and avoided overhead start zones. 

Today we found:

- Whompfing collapses at: 6700' SW aspect, 6200' S aspect, 6400' SE aspect, 6800' ridgeline X 2, and 6700' N aspect

- Active wind-loading onto NE aspect, forming reactive cornices.

- Height of snow ranged 75 cm to 110 cm above 6000'.

With a storm on deck, I expect the current weather forecast to make touchy avalanche conditions.

Snowpack, Avalanche, Weather Images: 
Travel Details
Region: 
Whitefish Range - Southern (south of Coal Creek)
Activity: 
Skiing
Snowpack Details
Snowpack and Weather Details: 
Hide Terrain
Elevation of observation: 
5000-6500 ft
Above 6500 ft
Aspect(s) of observation: 
N
NE
E
SE
S
SW
Red Flags: 
Shooting cracks
Collapsing / whumpfing noises
Persistent Weak Layers: 
Surface Hoar
Facets or Faceted Crust
Buried
New Snow in the past 24 hours: 
2.00in.
Total Snow Depth: 
80
More comments about the snowpack and weather: 
Red Flags: The most unexpected red flag was a ~150' shooting crack that crossed the slope above us. This collapse occurred after two of us walked onto the slope, dug a pit, and on the exit, the entire slope collapsed. We noticed it failed on facets below a rime crust. This crust was 30cm below the surface and formed prior to the weekend storm. The slope angle was 32 degrees where the shooting crack occurred. Weather: Sky cover varied from obscured to overcast throughout the day. Mostly S1 with one brief period of S4. Pits: 6600' SE aspect ECTN X 2 down 25 cms, 6700' N aspect ECTN X 2 down 50 cms, 6650' E aspect ECTN X 2 down 50 cms. All failed on facets below rime crust. Buried surface hoar was found on a west aspect at 6600'.
Blowing Snow: 
Light
Wind Speed: 
Light (Twigs in motion)
Wind Direction: 
South
Air temperature: 
Below Freezing
Sky Cover: 
Obscured by fog, etc (X)
Highest Precipitation Rate: 
Moderate Snowfall (S2)