Recent Avalanches? | No |
Collapsing (Whumphing)? | No |
Cracking (Shooting cracks)? | Yes |
Toured up to treeline on Pete’s N. We first climbed up to the top of treeline on the north shoulder of Pete’s N and dug a set of pits around 2000′. Then we descended and climbed back up to treeline to dig another set of pits in a more wind scoured area above Pete’s creek.
Recent Avalanches? | No |
Collapsing (Whumphing)? | No |
Cracking (Shooting cracks)? | Yes |
We had some small shooting cracks on wind loaded features at treeline. Wind slabs ranged from 6 - 12" deep.
Moderate to heavy snowfall throughout our tour. Winds were light in the trees and moderate at treeline. Wind speeds increased in the afternoon. Temperatures were in the teens.
We started the day on a 1 cm breakable crust at the parking lot. This went away by about 1000 - 1200'. Above there was about 30 cm of soft snow on the surface. On the way out there were about 10 cm of new snow on top of the crust that had fallen during our tour.
We dug pits in two drastically different locations. The first spot was near treeline at 2100' on the north shoulder of Pete's N on a protected slope in the forest with 270 cm total snow depth. In this location the snowpack was generally right side up with about 35 cm of soft snow above a thin crust from 1/25. We had consistent results on the layer with CT 19,21 and ECT N 19,21. We looked at the grains above and below the crust and found decomposing new snow in both locations.
The second set of pits was also at 2100' but on the other side of Pete's N near the normal uptrack and above Pete's Creek. We were intentionally looking for a thin spot in the snowpack to see if those areas were harboring weak layers. The total snow depth was 150 cm here and we found a much weaker overall snowpack structure. With several crusts in the upper 50 cm of the snowpack and a few layers of buried facets around the lower crusts. Our tests showed that the facets could still propagate a fracture with an ECT P 26 and CT 19 SC. I would guess that this thin and weak snowpack structure is isolated to thin wind scoured areas and that the crusts above the facets are adding a fair bit of strength to the upper snowpack that is not really captured in our instability tests.
First pit in the fatter 270 cm deep snowpack (Photo from Andy Moderow)
Second pit in a wind swept area with 150 cm deep snowpack (Photo from Andy Moderow)
Wind slabs were breaking easily on ridge with a small cornice at treeline about 12" deep
Shooting cracks in shallow wind loaded area on N shoulder of Pete's N
Unexpectedly snowy day in Turnagain Pass. We had about 3-4" of snowfall during our 4 hours in the field.