Flathead Range Ski Tour - Bactrian Devil

Location Name: 
Flathead Range
Observation date: 
Thursday, March 5, 2020 - 22:30

Is this an Avalanche Observation: 
No
Observation made by: Public

Tabs

Quick Observation

General:

Began tour under broken skies, no precipitation, light west winds, and air temperatures below freezing.  As the day progressed and elevation was gained, southwest winds increased and wind loading on northeasterly aspects was observed.  By early afternoon, air temperatures had increased to freezing or above freezing at all elevations.

Avalanche:

No shooting cracks, collapsing, and/or audible failures observed while in the field.

No evidence of recent slab avalanche activity (Past 24 hours).  However, relatively recent natural slab avalanche activity was observed on steep and unanchored northeasterly/ easterly aspects above 7000' elevation (Photos Attached).  It appears these slab avalanches were triggered by cornice fall.

Cornice growth on north/ northeast aspects has been substantial.  In a few locations today cracks were observed where the cornice is pulling away from remaining snow at ridgeline elevations (Photo Attached).

Snowpack

Below 5500': Snowpack in the morning was dry and frozen but on descent in mid-afternoon- all aspects were experincing air temperatures above freezing and affects of snow melt.

5500' to 6500': Snowpack remained relatively dry on shaded aspects through mid-afternoon but solar aspects were melting and becoming sun affected.

6500' and above: Snowpack surface remainded dry and/or frozen through at least early afternoon.  Some areas of wind affected snow were encountered with 2"-4" surface windslab formation on easterly and northerly aspects.

 

 

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

to ~7700 ft

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
NW
Red Flags: 
Blowing snow
Rollerballs / pinwheels
Persistent Weak Layers: 
Not observed
New Snow in the past 24 hours: 
0.00in.
More comments about the snowpack and weather: 
By mid-late afternoon, snow sticky under trees about 5800'. Sticky on open slopes below ~5400 ft. Rollerballs w turns and traverses, but no natural wet loose slides. Thin crust on SW an W faces at upper elevations that was softening by midday. On SE slopes above 7000 feet, ~8" dense snow on 3/1 crust that took considerable pulling to break in hand pits.
Blowing Snow: 
Light
Wind Speed: 
Moderate (Small trees sway)
Wind Direction: 
Southwest
Air temperature: 
Below Freezing
Sky Cover: 
Mostly Cloudy (BRK)
Avalanche Details
Avalanche Details: 
Date and Time of Avalanche: 
Saturday, February 29, 2020 - 12:15
Number of avalanches: 
1
Avalanche Type: 
Hard Slab
Failure Plane/Weak Layer: 
Unknown
More information or comments about the avalanche: 

Debris has some snow on it. Not especially blicky. Guessing triggered by cornice fall; no similar slides in basin on similar terrain.

Hide Trigger
Trigger: 
natural
Trigger Modifier: 
Cornice Fall Triggered
Hide Terrain
Start Zone Slope Angle: 
40
Aspect: 
East
Starting Elevation: 
7500
Hide Size
Destructive Size: 
D2 Could bury, injure, or kill a person.
Avalanche Length (Vertical Run): 
500ft.
Avalanche Width (Average width): 
125ft.
Avalanche Location: