| Recent Avalanches? | Yes |
| Collapsing (Whumphing)? | No |
| Cracking (Shooting cracks)? | No |
Observation: Summit
Location: Tenderfoot
Standard up-track up Tenderfoot to a high point of 3400′. Looking for the distribution and reactivity of the 1/21 BSH (MLK Jr BSH) in the upper elevations of Summit.
Obvious signs of instability
Observer Comments
Cornice fall of SW Aspect of Butch above 3500'
Natural D1.5-2 Slab Avalanche SW Aspect of Butch above 3000'
Weather
Mid 20s
Clear-Few sky above 2k
Broken Valley fog 2-2.5k throughout the day
No Precip
Calm-Light NW Winds
Snow surface
Parking lot ~ 1700' - Eggshell Rain Crust of thin snowpack 10"
~1700' - Loss of Eggshell crust, new precip. 4-10" increasing as elevation increased
~1800' - New Surface Hoar formation 5-7mm is present
~2700' - Obvious wind effect/transport appears. Variable scoured surface with 1-5" new precip on it depending on wind effect. Locations with low wind effect still had SH formation.
Snowpack
The MLK Jr Day (1/21) BSH layer was still found wide spread at multiple elevation bands. We saw it in multiple lower-mid elevation (1500-2500') hand pits and in test pits on different wind effected aspects within upper elevation bands (above 3000').
Beginning at 1800' - we found a 1" melt freeze / near surface facet crust interface (NSF/MF/DF .5mm) above the MLK Jr BSH buried approx 12" down and shear with moderate force in a planar fashion. The hand shears were failing on the MF/NSF interface, not within the BSH. This was the same type of interface we were finding at Tincan earlier in the week.
2400'- we found the MF interface (NSH/MF/DF .5mm) layer was decomposing to more of a thin eggshell above the MLK Jr BSH buried approx 16" down and shear with moderate force in a planar fashion.
2700'- we found the MLK Jr. BSH buried approx 10" down and shearing with moderate force in a planar fashion - on the MLK Jr. Layer.
3000'-We explored a very wind scoured SW aspect with a shallow snowpack (65cm) with approx 6" new precip on 20" of decomposing/faceting pencil hard melt freeze layers with large (8-10mm) BSH throughout as well. This all sat on top of a weak layer 10-12mm Depth Hoar. This pit gave zero results in the stability tests. (CTN ECTX).
3400'-We explored a wind loaded SW aspect with deeper snowpack (210cm). In this we found the MLK Jr BSH (4-6mm) buried 12" down on top of a 12" knife hard wind layer. We also found the 1/11 BSH (2-5mm) directly below the knife hard wind layer. This showed propagation propensity on the MLK Jr BSH (ECTP27).
Upper Tenderfoot Pit - 3400' - SW - HS:210
CT15 down 30cm
ECTN15 down 20cm new old interface
ECTP27 down 30cm on 4-6mm MLK Jr BSH
Tenderfoot 1800'- Handpit with a planar shear 12" down
Tenderfoot 1800- Melf Freeze/NSF/DF Interface above the MLK Jr BSH
Transport visible across valley over the fog layer (VG 2-2.5K)
Tenderfoot 3000' - Pit wall - New precip on top of MF/interface over depth hoar
Tenderfoot 3000' - Depth Hoar - 10-12mm
Tenderfoot 3400'- 1F slab showing propagation over a knife hard wind slab.
New widespread surface hoar (3-7mm)
Natural Ax SW Aspect of Butch 3000'
Fresno and Colorado Coverage