Professional Observation - John F. Stevens Canyon, southern Glacier NP

Location Name: 
Professional Observation - John F. Stevens Canyon, southern Glacier NP
Region: 
Flathead Range/Glacier National Park - John F. Stevens Canyon
Date and time of avalanche (best estimate if unknown): 
Thu, 01/14/2016 - 12:00
Location Map: 


Red Flags: 
Recent avalanche activity
Recent loading by new snow, wind, or rain
Obvious avalanche path

Observation made by: Professional Observer
Avalanche Observations
Avalanche Type: 
Dry
Slab
Trigger type: 
Skier
Crown Height: 
3 ft
Aspect: 
Northeast
Weak Layer: 
Other - explain below
Avalanche Width: 
70ft.
Terrain: 
Below Treeline
Elevation: 
5 600ft.
Bed Surface: 
Other - explain below
Avalanche Length: 
400ft.
Number of similar avalanches: 
3
Number of people caught: 
0
Number of partial burials: 
0
Number of full burials: 
0
More detailed information about the avalanche: 

DATE

SUBMITTED:

TIME SUBMITTED:

OBSERVATION LOCATION

OBSERVATION

DATE:

SUBMITTED BY:

1/14/2016

        1730

Shed 6/7 Ridge

1/14/2016

Steiner

Toured up the looker’s right side of the Shed 7 path and then ascended onto the Shed 7 East/ Shed 6 ridge. Conducted belayed ski cuts in Test Slope 1, 2 and 3. Also, collected data from a crown profile in Test Slope 2. Skiing conditions were poor on ascent and descent due to surface crusts, unconsolidated moist snow, and dense wind pillows.

Windloading occurring on easterly and northeasterly aspects.

Shooting cracks under single skier weight in snow pillows on leeward aspects.

No audible collapsing or remote triggering of avalanches.

Conducted two (2) compression tests (CT) in Test Slope 2.  These were conducted as part of a profile dug into the crown of an avalanche (crown profile) that was intentionally triggered by us.

CT results were CT19 Q2 @ 90 cm from the snowpack surface in the Test Slope 2 crown profile.  Both CT tests failed on the weak layer interface of the previously intentional triggered avalanche.

The weak layer interface of both the CT and intentionally triggered avalanche consisted of a very thin 2-3 mm surface hoar (sh) positioned atop a pencil minus (P-) bed surface.

Evaluation of the snowpack was not conducted at deeper snowpack depths than the bed surface/ weak layer interface of crown profile.  However, total snowpack depth at the Test Slope 2 location was 230 cm and snowpack surface temperature was -3.30 C. 

Evidence of relatively small natural slab avalanche activity observed in Test Slopes 1 and 3.  Also saw recent debris in the northeasterly aspect of the Shed 5 starting zone.  Associated debris terminated in upper 1/3 of path.  Character of natural slab activity not known due to new snow and recent wind deposits.

Also, as previously referenced, we did intentionally trigger a relatively small slab avalanche in the starting zone of Test Slope 2 at approximately 1696 m (5600 feet) elevation. This avalanche is classified as (SS-ASi-R2-D1.5-I) and was approximately 30 meters (m) in width.  Crown height measured 130 cm at its maximum thickness and 30 cm at its minimum thickness.  Hardness varied between F and 1F-.  The avalanche traveled approximately 130 lineal m to the max runout of the test slope and dropped approximately 90 m in vertical height.

 

BNSF AVALANCHE SAFETY FIELD OBSERVATIONS SUBMITTED TO FLATHEAD AVALANCHE CENTER AND GLACIER NATIONAL PARK ARE BEING PROVIDEDED IN ACCORDANCE WITH THE TERMS AND CONDITIONS SPECIFIED GLACIER NATIONAL PARK SPECIAL USE PERMIT.  

THESE OBSERVATIONS REPRESENT SITE SPECIFIC INFORMATION INTENDED FOR THE BNSF AVALANCHE SAFETY PROGRAM AND IN NO WAY ARE TO BE CONSTRUED AS A PUBLIC/ RECREATION AVALANCHE FORECAST.  

Avalanche Photos: 
Weather Observations
More detailed information about the weather: 

Overcast skies, moderate to strong westerly winds, and light to moderate snowfall throughout the day. Air temperatures were in upper twenties (F) at all elevations. Wind loading occurring on easterly and northeasterly aspects.

Activity: 
Skiing