| Trigger | Natural | Remote Trigger | 0 |
| Avalanche Type | Unknown | Aspect | Unknown |
| Elevation | unknown | Slope Angle | unknown |
| Crown Depth | unknown | Width | unknown |
| Vertical Run | unknown |
Avalanche: Turnagain
Location: Tincan
Standard route up Tincan to Todd’s Bowl. Noticed a recent slab avalanche on SE aspect of Seattle Ridge, an area known as Little Sweden. The slide covered several snowmachine tracks. This was confirmed in the evening to be triggered by a snowmachiner around 12:30pm 3/11. No one caught.
Obvious signs of instability
| Recent Avalanches? | Yes |
| Collapsing (Whumphing)? | No |
| Cracking (Shooting cracks)? | No |
Observer Comments
Recent slab avalanche on SE aspect of Seattle Ridge
Weather
Clear and sunny
Temps in the teens F - and noticeably cooler in shaded zones
Calms winds
Snow surface
Variable surfaces. Hard pack/sastrugi along ridges, faceted "recycled" powder in protected areas below ridge lines in the alpine.
Below 2500' 4-6" of loose faceted snow.
Below 1400' surface hoar 4-6mm in size sitting on 4-6" loose faceted snow.
*2cm sun crust was found on steep South facing slopes at all aspects.
Snowpack
Probed around in starting zone of Todd's Bowl and height of snow ranged from 180cm to 280cm.
Dug a quick test pit at 3500' in Todds, HS=245cm, 42 degree slope, N aspect - Pit height was 115cm and was right side up. The surface had a 1cm wind crust capping 4F hard snow. The top 35cm had varying layers of 4F to 1F hard snow. Below this was all Pencil hard snow. Compression Tests failed 20cm below the surface with moderate force, and failed again 35cm below the surface with strong force. Both failed on 0.5-1mm near surface facets, but in both cases the slab broke into pieces.
Slab avalanche - likely snow machine triggered on SE aspect of Seattle Ridge. Timing was within the last three days. Photo taken from Seward Hwy.
View from Tincan of Slab avalanche on SE aspect of Seattle Ridge
Some textured snow is deceivingly soft in protected areas, like these recent tracks in Hippy Bowl, compared to the Anti tracks near the ridge.
Sun crust found on steep Southern facing aspect at 2000'
A few piles of loose snow from recent tracks in Todd's bowl
Glide cracks on S face of Eddies
Glide cracks on SE aspect of Seattle
Full view of the South face of Eddies - note that the glides are not across the entire face, unlike last year!
Near surface facets found just below wind skin in test pit on Todd's Bowl. Grid size =1mm.