Got In. Got It. Got Out.

Location Name: 
Forecaster Observation - Flathead Range
Observation date: 
Thursday, January 6, 2022 - 18:30

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

Tabs

Quick Observation

Went to the Flathead Range today to monitor the start of the storm and look at the layers of facets buried where the snowpack is shallowest. 

  • We saw increasing snowfall rates. Very light snowfall throughout the morning began to pick up around 1pm. By 330pm we noticed moderate snowfall. 
    • 1 inch of very low density new snow fell by our exit at 4pm. The new snow sat atop 3-6 inches of soft recent snow.
    • In open terrain above about 5800 feet the new and recent snow sits on old, hard wind slabs.
    • We tested many steep slopes and got minimal sluffing. On one short, north-facing, 45 degree pitch we we able to trigger a loose dry avalanche that entrained the recent snow.
    • We saw 5 more small sluffs in steep chutes we expect were about 24 hours old.
  • We experienced increasing wind and blowing snow.
    • When we got above 6000 feet around 11am southwest winds were light to moderate with occasional strong gusts. We saw puffs of blowing snow. By our exit winds were moderate and blowing snow was consistent. 
    • We found many ridgelines with wind-affected snow and fresh cornices. Mostly of these were stubborn - not breaking wider than our skis with kicking. None of the ones we kicked triggered more than very small sluffs on the slopes below.
  • Temperatures were rising.
    • We took air temperature at 10am: 1 deg F. When we took it at 345pm at about the same elevation: 12 deg F.
    • The rising temperature was having the subtle effect of consolidating the new and recent snow. We did a shovel tilt test and the surface snow slid off harder snow below with only one "baby burp."
    • We got just enough cracking in the new and recent snow to clue us in that it was starting to form a slab.
  • We tested a layer of buried facets from mid-December at lower and middle elevations where the snowpack was shallowest. We got no propagating results.
    • The facets are bigger, looser, and more developed than I have seen them before. They're 1-2 feet below the surface depending on elevation.
    • Below 4500 feet elevation the sugar rests above and below a hard crust from December 18th. Above that elevation, the crust is replaced by graupel, but the facets remain, sadwiched between 2 thin hard slabs.
    • We suspect that these weak grains will be a problem with a thicker, stiffer slab on top.

So, our takeaways: We have stiffer snow buried with a weak layer on top (either the low density recent snow, or the buried facets depending on location). The slab looks like it's coming tonight.

Snowpack, Avalanche, Weather Images: 
Travel Details
Region: 
Flathead Range - Middle Fork Corridor
Route Description: 

To 6800 feet

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
SE
S
Red Flags: 
Avalanches from the past 2 days
Blowing snow
Persistent Weak Layers: 
Facets or Faceted Crust
Buried
New Snow in the past 24 hours: 
4.00in.
Total Snow Depth: 
2m
Blowing Snow: 
Intense
Wind Speed: 
Moderate (Small trees sway)
Wind Direction: 
Southwest
Air temperature: 
Below Freezing
Snow line: 
Canyon Floor
Sky Cover: 
Obscured by fog, etc (X)
Highest Precipitation Rate: 
Moderate Snowfall (S2)
Avalanche Details
Avalanche Details: 
Date and Time of Avalanche: 
Thursday, January 6, 2022 - 14:30
Number of avalanches: 
1
Avalanche Type: 
Loose Dry/ Sluff
Failure Plane/Weak Layer: 
New/old snow interface
Hide Trigger
Trigger: 
skier
Trigger Modifier: 
Intentionally Triggered
Hide Terrain
Start Zone Slope Angle: 
45
Aspect: 
North
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): 
75ft.
Avalanche Width (Average width): 
30ft.
Avalanche Location: 
Date and Time of Avalanche: 
Wednesday, January 5, 2022 - 12:00
Number of avalanches: 
5
Avalanche Type: 
Loose Dry/ Sluff
Failure Plane/Weak Layer: 
Within storm snow
More information or comments about the avalanche: 

Times estimated

Hide Trigger
Trigger: 
natural
Hide Terrain
Start Zone Slope Angle: 
50
Aspect: 
Northwest
Starting Elevation: 
near-treeline
Hide Size
Destructive Size: 
D1 Relatively harmless to people.
Relative Size: 
R1 Very Small
Crown Height: 
Less than 1 ft
Avalanche Length (Vertical Run): 
100ft.
Avalanche Width (Average width): 
15ft.
Avalanche Location: