Skip to main content
Flathead Avalanche Center
Responsive Links
Advisories
Observations
Donate
Forecasts
Avalanche Forecasts
Whitefish Range
Swan Range
Flathead Range and Glacier N. P.
Archives
Sign up for emailed forecasts
Tutorials
How to read the Forecast
Avalanche Problems
The Danger Scale
Observations
Observations
Field Observations
Observations prior to Oct.1 2022
Incidents
Snowpack Tracker
Submit Observation
Weather
Western MT Backcountry Weather Forecast
Weather Station Table
Weather Station Map
Education
Classes and Events
Course List
Event Calendar
Class Details and Registration
Northern Rockies Snow & Avy Workshop
Mentorship
Videos
Throttle Decisions Video Series
Local Awareness Videos
Online Resources
Avalanche Encyclopedia
Avalanche Canada tutorial
Know Before You Go Online Course
Backcountry Ascender - Motorized Specific
BCA Tutorial
FOFAC Recorded Classes
About
Friends of the Flathead Avalanche Center
FOFAC
How To Help
Sponsors
Donate
Flathead Avalanche Center
Blog
Staff
Contact
Annual Reports
Donate
Small wind slabs and one big collapse
Location Name:
BNSF Avalanche Safety - Snowslip Mtn. GNP
Observation date:
Tuesday, January 5, 2021 - 23:00
Is this an Avalanche Observation:
Yes
Observation made by:
Public
Location
Tabs
Quick Observation
Toured up the Shed 6/7 ridge to the Shed 7 weather station at 6100’ elevation.
Descended the Shed 5 area.
Objectives were to assess the recent wind-loading and snowpack stability with close attention to the Dec. 9th and 22nd crusts and check on the weather station.
No avalanche activity observed aside from a mini wind slab (D1) ski-triggered on a test slope on a SE aspect and 5600’ elevation (Test Slope 2 - photo). Debris terminated well above the rail.
Overnight snowfall totals above 6000’ elevation were about 3-4”.
Several generations of wind slabs above 5000’ from the consistent westerly winds over the past week. Some of these were reactive to ski cuts, while others were unreactive.
Shed 7 West cornice has grown considerably over the past week.
Breakable crust on the snowpack surface from the Canyon floor up to about 4800’.
Hasty pit dug at 5500’ on a SE aspect and a wind-loaded location. HS=43” with the Dec 22nd crust buried 20” down and the Dec 9th crust 30” down from the surface. No propagation and ECTN28 on the Dec 22nd crust.
One audile collapse in an area known as Test Slope 2 (5600’, SE aspect) after a few forceful ski stomps. Same location as the small avalanche mentioned above.
Mostly overcast skies with an occasional break for a ray or two of sunshine. No precipitation with light westerly winds.
Daytime high air temperatures warmed to about freezing on the Canyon Floor and up to the mid-20s/high teens °F at elevations above 6000’.
Snowpack, Avalanche, Weather Images:
Travel Details
Region:
Flathead Range/Glacier National Park - John F. Stevens Canyon
Activity:
Skiing
Avalanche Details
Avalanche Details:
Date and Time of Avalanche:
Tuesday, January 5, 2021 - 13:30
Number of avalanches:
1
Avalanche Type:
Soft Slab
Failure Plane/Weak Layer:
New/old snow interface
Trigger
Trigger:
skier
Trigger Modifier:
Intentionally Triggered
Terrain
Aspect:
Southeast
Starting Elevation:
5600
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):
25ft.
Avalanche Location:
Javascript is required to view this map.
