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Windy in JFS Canyon
Location Name:
BNSF Avalanche Program-Snowslip Mtn. GNP
Observation date:
Wednesday, January 2, 2019 - 18:00
Is this an Avalanche Observation:
Yes
Observation made by:
Public
Tabs
Quick Observation
Travelled up the south face of Snowslip Mtn. via the Shed7/6 ridge to the Shed 7 weather station then continued up the ridge to 7000 feet and the Snowslip weather station.
Objective was to assess new snowfall amounts along with the recent wind,-loading. Also needed to keep investigating the snowpack structure, specifically the persistent weak layer(s) near the bottom of the snowpack.
Descended via Shed 7 West.
Overcast skies, with intermittent S-1 snowfall and moderate to strong west winds near the ridge crests. Air temperatures were in the 20s °F above 6000 feet elevation for most of the day.
The snowpack is finally deep enough to ski from the rail grade. Our manual weather/snowpack measurement stations in the Canyon both show about 14 inches of snow on the ground. Essex has 23 inches.
Above 5500 feet elevation moderate to strong westerly winds were actively loading east aspects. Still we observed few signs of instability other than a few minor shooting cracks running only about 2-4 feet.
The cornices above Shed 7 West that were almost fully eroded earlier this week by east winds are now re-building due to the recent snow and steady westerly winds.
We dug a snowpit in the upper reaches of Shed 7 West at 6650 feet elevation on as easterly aspect (pit profile below). The poor snowpack structure remains with the December facets present near the ground underneath a firm mid pack of 1F hardness. The first Extended Column Test resulted in ECTX, the second in ECTN16 on a density change between layers about 16 inches down.
One small (D1.5) slab avalanche triggered by a falling cornice ran about 700 vertical feet from the top of Shed 7 West. This debris terminated in the upper 1/3rd of the avalanche path.
No other avalanche activity observed.
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, January 2, 2019 - 08:00
Avalanche Type:
Soft Slab
Failure Plane/Weak Layer:
New/old snow interface
Trigger
Trigger:
skier
Trigger Modifier:
Cornice Fall Triggered
Terrain
Aspect:
East
Starting Elevation:
above-treeline
Size
Destructive Size:
D1.5
Avalanche Length (Vertical Run):
700ft.
