Crusts, facets, and collapses

Location Name: BNSF Avalanche Safety - Running Rabbit Mtn GNP Observation date: Tuesday, February 16, 2021 - 18:45	Is this an Avalanche Observation: No

Observation made by: Public

Tabs

Quick Observation

Toured on the ridge separating the Shed 11 and Shed 10.7 avalanche paths to the Shed 11 weather station, then continued to the uppermost starting zone of Path 1163. Kept on the ridgeline and mostly out of avalanche terrain. Descended the skin track.
Objectives were to look for avalanche activity and assess the snowpack structure and stability in this area.

The poor snowpack structure associated with the Jan. 13th crust(s) persists. We had two audible collapses on southerly aspects on terrain above 6500’. One was very loud and we could feel the snowpack drop beneath us.
Dug our first snow pit below the weather station at 6400’, south aspect. HS=65” and the Jan. 13 crust was 22” down from the surface. Propagation on the first Extended Column Test, ECTP25 on a layer of facets just below the crust. ECTN24 on the same layer with the next test.
Second snow pit was adjacent to the slope with the loud collapse, SSE aspect 6850’. HS=79” and the Jan. 13th crust was about 26” down from the surface. ECTN26 on a layer of facets just below the crust, compression test yielded CT24, Sudden Planar on same layer. Second ECT we had propagation on said layer at 24 taps.
The Jan. 13th crust disappears just above 7000’.
Below 6000’ the near-surface snowpack generally consists of facets about 6-12” deep on top the Jan. 13th crust, interspersed with areas of dense wind slabs 1-2’ thick (or more) on westerly aspects.
On easterly aspects exposed to the wind, many slopes had been scoured down to the Jan. 13 crust with only a couple inches of powder from last night resting on top.

A mostly cloudy day but with occasional breaks to blue sky for a few minutes. On again/off again snow showers with about 1” accumulation by the end of the day.
Mostly calm or very light westerly winds all day.
Daytime high air temperatures reached the mid-20s °F on the Canyon floor and the mid-teens °F above 6000’.

Travel Details

Region:

Flathead Range/Glacier National Park - John F. Stevens Canyon

Activity:

Skiing