More photon therapy, please!

Location Name: 
Forecaster Observation - Running Rabbit Mountain
Observation date: 
Wednesday, December 29, 2021 - 18:30

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

Tabs

Quick Observation

Climbed up southerly slopes on Running Rabbit Mountain to see how winds from the competing Polar and Pacific air masses have affected the snow surface in a canyon that funnels those winds. Also did a welfare check on the Shed 11 weather station. 

  • While wind-drifted and wind-hardened snow was common at all elevations, the thin, small hard slabs were the most reactive (cracks 5-15 feet when weighted). These were confined to top-loaded southerly slopes and cross-loaded ridges (image). 
  • We triggered two harmless hard slabs on test slopes on southerly slopes at upper elevations (image, avalanche tab). 
  • We saw two older loose dry avalanches on an upper elevation southerly slope (avalanche tab).
  • We could not see distant slopes due to clouds. 
  • The snowpack on mid-elevation slopes was right-side up (progressively harder with depth) with no evident weak layers. Slope cuts on steep slopes did not produce results, nor did skiing a large, open bowl. 
  • The weakest snow is at low elevations (below 5000 feet). A layer of soft facets is sandwiched by a 4 finger slab above and a hard rain crust. This structure cracked at switchback corners (image). We accidentally triggered a small soft slab avalanche (avalanche tab) on a steep slope involving this structure. This structure may persist and prove problematic when loaded. 
  • Good coverage down low for this time of year. 

Took 3 puffy jackets; only used 2. Our ascent was sheltered from the west-northwest winds and surprisingly comfortable, particularly while recieving photon therapy when sun was out. 

Snowpack, Avalanche, Weather Images: 
Travel Details
Region: 
Flathead Range/Glacier National Park - John F. Stevens Canyon
Route Description: 

4075-7250 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: 
SE
S
SW
Red Flags: 
Shooting cracks
Blowing snow
Persistent Weak Layers: 
Facets or Faceted Crust
Buried
New Snow in the past 24 hours: 
0.00in.
Total Snow Depth: 
100 cm
More comments about the snowpack and weather: 
Partly cloudy in until about late morning. Then broken skies with some clouds below ridges/ in valleys. -6 deg at highway 10 AM; 3 deg @ 4 PM. Calm w occasional light gusts on southerly slopes; winds light to moderate at ridgeline, from west-northwest. Light blowing snow near ridges. Low elevations: HS 50-75 cm. midpack crust from 12/18 rain event. ~10 cm F+ hard FC and graupel above topped by 20-30 cm thick 4F slab. ECTN 13 on FC/ graupel. May be weak, nasty structure when loaded. Mid elevations: HS 100-120 cm. Progressively harder with depth - F+ near surface to 1F near ground. No obvious weak layers, even near ground, though graupel layer visible 40 cm below surface. ECTN 24. ECTX below that.
Blowing Snow: 
Light
Wind Speed: 
Moderate (Small trees sway)
Wind Direction: 
West
Snow line: 
0'
Sky Cover: 
Mostly Cloudy (BRK)
Avalanche Details
Avalanche Details: 
Date and Time of Avalanche: 
Wednesday, December 29, 2021 - 15:00
Number of avalanches: 
2
Avalanche Type: 
Hard Slab
Failure Plane/Weak Layer: 
New/old snow interface
Hide Trigger
Trigger: 
skier
Trigger Modifier: 
Intentionally Triggered
Hide Terrain
Start Zone Slope Angle: 
40
Aspect: 
South
Starting Elevation: 
above-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): 
15ft.
Avalanche Width (Average width): 
15ft.
Avalanche Location: 
Date and Time of Avalanche: 
Wednesday, December 29, 2021 - 16:00
Number of avalanches: 
1
Avalanche Type: 
Soft Slab
Failure Plane/Weak Layer: 
Old snow
More information or comments about the avalanche: 

Triggered accidentally when ski tumbled over rock after catching ski. Felt snow release in wide sluff/ small slab. Propagated < 10'; slid with debris < 10' down slope. Debris traveled another 5 feet. Harmless, unless I'd been alone and wound up in treewell. 

Hide Trigger
Trigger: 
skier
Trigger Modifier: 
Accidentally Triggered
Hide Terrain
Start Zone Slope Angle: 
38
Aspect: 
South
Starting Elevation: 
4300 feet
Hide Size
Destructive Size: 
D1 Relatively harmless to people.
Relative Size: 
R1 Very Small
Crown Height: 
1 ft
Avalanche Length (Vertical Run): 
15ft.
Avalanche Width (Average width): 
8ft.
Hide People Involved
Number of people caught: 
1
Number of partial burials: 
0
Number of full burials: 
0
Avalanche Location: 
Date and Time of Avalanche: 
Monday, December 27, 2021 - 12:00
Number of avalanches: 
2
Avalanche Type: 
Loose Dry/ Sluff
Failure Plane/Weak Layer: 
Within storm snow
Hide Trigger
Trigger: 
natural
Hide Terrain
Start Zone Slope Angle: 
38
Aspect: 
South
Starting Elevation: 
above-treeline
Hide Size
Destructive Size: 
D1.5
Relative Size: 
R2 Small
Avalanche Length (Vertical Run): 
150ft.
Avalanche Location: