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Winter Returns
Location Name:
BNSF Avalanche Safety - Snowslip Mtn GNP
Observation date:
Wednesday, March 11, 2020 - 22:15
Is this an Avalanche Observation:
Yes
Observation made by:
Public
Tabs
Quick Observation
Toured up the SE ridge of Snowslip Mountain above the Burnout and Sheds 4D, 5, and 7 paths to the Shed 7 weather station. Then continued up to about 6700 feet in the Shed 7 West path.
Descended the Shed 5 path.
Objectives were to observe the past 24-hour snowfall totals and the extent of recent wind-loading, and look for any new avalanche activity.
One wet loose sluff, Destructive Size 1 of 5 ran today in a small path on the rail called Umbrella Fence, located between Sheds 7 and 6. Associated debris made a small pile next to Main 1 about 1-4 feet deep and 15 feet wide.
A couple small D1 loose dry sluffs intentionally triggered with ski cuts in the Shed 5 path around 5500 feet (photo).
No slab avalanches observed.
New snowfall overnight and today ranged from 4-10 inches on the Canyon floor with greater amounts at the east end of the Program Area. Above 6000 feet there was about a foot of new snow. This was accumulating on a stout melt-freeze crust that appeared to exist everywhere where I travelled except for shady aspects above 6000 feet
Snow surface was moist below about 5500 feet and a lot of the new snow consisted of graupel.
Moderate to strong SW winds were actively loading leeward slopes and forming fresh wind slabs for much of the day above 5500 feet.
Ski cut many steep test slopes resulting in very few signs of instability. New wind slabs were either unreactive or only produced minor cracking (2-3 feet long).
Ski cuts also had limited effect at initiating loose snow sluffs despite all the fresh snow deposited on a melt-freeze crust.
Dug a snow pit in the Shed 7 West path at 6600 feet on an east aspect. Total snow depth was 75 inches with about a foot of new snow on top of the most recent melt-freeze crust. Extended Column Test yielded ECTN10 about 12 inches down on the new snow interface. No additional fractures observed.
Mostly cloudy skies with steady snow and graupel showers interrupted by brief periods of broken skies and no precipitation. Snowfall was heavy at times, up to S5 intensity for short periods. Half inch of new snow covered my pack in about 10-15 minutes while working in a snow pit in the Shed 7 West path around 1400. (photo).
Moderate SW winds with strong gusts above 5500 feet. Winds on the Canyon floor were light from the west or calm.
Air temperatures on the Canyon floor hovered just above freezing this afternoon and were in the mid-20s °F above 6000 feet.
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:
Wednesday, March 11, 2020 - 15:00
Number of avalanches:
2
Avalanche Type:
Loose Dry/ Sluff
Failure Plane/Weak Layer:
Within storm snow
More information or comments about the avalanche:
Trigger
Trigger:
skier
Trigger Modifier:
Intentionally Triggered
Terrain
Aspect:
South
Starting Elevation:
near-treeline
Size
Destructive Size:
D1 Relatively harmless to people.
Relative Size:
R1 Very Small
Crown Height:
Less than 1 ft
Avalanche Length (Vertical Run):
75ft.
Avalanche Location:
Javascript is required to view this map.
Date and Time of Avalanche:
Thursday, March 12, 2020 - 10:00
Number of avalanches:
1
Avalanche Type:
Wet Loose
Failure Plane/Weak Layer:
Within storm snow
More information or comments about the avalanche:
Trigger
Trigger:
natural
Terrain
Aspect:
Southeast
Starting Elevation:
below-treeline
Size
Destructive Size:
D1 Relatively harmless to people.
Relative Size:
R1 Very Small
Avalanche Length (Vertical Run):
100ft.
Avalanche Location:
Javascript is required to view this map.
