Observation: Summit

Location: Tenderfoot Ridge

Route & General Observations

Standard Tenderfoot skin track up to ~2800′. Dug a pit at tree-line at 2420′.
We wanted to learn about the distribution of crust layers near the surface from the storm cycle this past week.

Red Flags
Red flags are simple visual clues that are a sign of potential avalanche danger. Please record any sign of red flags below.
Obvious signs of instability
Recent Avalanches?Yes
Collapsing (Whumphing)?No
Cracking (Shooting cracks)?No
Observer Comments

Same recent avalanches as observed by Haffener / Galoob on 01.18.2018. Did not see any debris that looked fresher than that.

Weather & Snow Characteristics
Please provide details to help us determine the weather and snowpack during the time this observation took place.

Thick valley fog persisted throughout the day up to 2200'. Temperature at Summit Lake at 11:00a was -9 C.
Above the fog -
Sky: Clear
Precip: None
Wind: Calm or very light out of the East.
Temp: -10 C.

Snow surface

Surface hoar of ~1cm observed at all elevations. This was sitting on 5-10cm of new snow, which was sitting on a 3-5cm breakable rain or melt/freeze crust. We observed that this crust was thinner and stiffer at lower elevations, becoming thicker but weaker up to 2000' or so. Above 2000' it remained 5cm thick and easy to punch through with a pole basket. We estimate that the rain line reached up to 2600' last week, because of a noticeable transition at that elevation from crust to dense new snow.


*see pit profile attached.
Notable Test Results:
We had some repetition of failure and propagation across CT24 and ECTP24 on rounding facets 70cm deep. This was a thick layer (20cm) of 1F snow, and the failures seemed to bounce around within it. We did not see anything cleaner than Q2. Propagation saw test result was difficult to interpret. The failure propagated a bit past the saw in the 70cm deep layer, stepped up into ~55cm deep 'layer' and propagated a bit further, then fractured vertically (red line in the photo is vaguely accurate).

Photos & Video
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