We did a crown profile of the avalanche which was likely human triggered on 2/19 on upper Stairstep.
It occurred on a West aspect, 38 deg, 3700' and failed on facets on a crust. The avalanche was approximately 175 ft wide and ran 100 ft. The size was D2 R3 and mostly soft slab with some hard wind slab blocks mixed in.
Observation: Hatcher Pass
Location: Stairstep
Toured from bottom of 16 mile lot up Stairstep, goals of the day being to check structure and stability in shallower snowpack and investigate an avalanche that occurred on 2/19.
Avalanche Details
Obvious signs of instability
| Recent Avalanches? | Yes |
| Collapsing (Whumphing)? | No |
| Cracking (Shooting cracks)? | No |
Observer Comments
No red flags other than the noted avalanche from 2/19 and the punk spines avalanche.
Weather
Surprisingly nice light and weather. Warm temps calm and sunny part of the day with clouds and flat light moving in as we were leaving (around 3pm).
Snow surface
A thin drizzle crust near the surface which was not enough to affect ski quality. Some near surface faceting taking place above crust.
Snowpack
As expected, structure is worse in areas with a thinner snowpack, at upper elevation, in areas that have previously avalanched, and/or have been exposed to more wind.
See snow pilot of avalanche and photo of pit sidewall for details.
We did not find any signs of instability in our snowpack tests at pit number 1 (ECTX PST55/100 End) at 3300' on a NNW aspect.
At the avalanche site at 3700' on a W aspect we had an ECTP15 and a PST 35/100SF and we also observed 4-6m rounding depth hoar.
First pit on our way up Stairstep
Avalanche debris. Bed surface was hard and icy
Pit profile at crown