| Trigger | Skier | Remote Trigger | Unknown |
| Avalanche Type | Soft Slab | Aspect | Northwest |
| Elevation | 2000ft | Slope Angle | 38deg |
| Crown Depth | 12in | Width | unknown |
| Vertical Run | unknown |
Avalanche: Turnagain
Location: Tincan Trees
Tincan Trees to 2200′
Avalanche Details
Small (D1) skier triggered soft slab breaking within recent new snow on a steep rollover at Tincan Treeline; crown looked to be ~1' deep at most, and a photo of debris is below. On similar terrain features steeper than 38 degrees, small slabs just slightly longer than ski length would occasionally break, but nothing else notable observed below treeline.
Obvious signs of instability
| Recent Avalanches? | Yes |
| Collapsing (Whumphing)? | No |
| Cracking (Shooting cracks)? | No |
Observer Comments
Obscured skies made for limited visibility in the alpine and on neighboring peaks throughout our day, but in one clear break several D1 loose avalanches with well defined edges were seen on steep slopes in the Seattle Ridge alpine as of 3 PM. Runout from a larger avalanche (~D2) was also seen in a larger gully on Seattle Ridge across from Sunburst. The angle was tough for this one from the side - see photo below - but it looked to be a loose snow avalanche that may have also triggered a section of slab within the gully feature.
Weather
Intense snowfall - ~2" per hour! - at the parking lot at 11 AM, with 12" of new snow overnight.
Snowfall rate slowed by 11:30, with ~3" falling between 11 AM - 3:30 PM when we left.
Obscured skies, with occasional patches of blue overhead.
The sun cast a shadow nearly half the time, even during periods of snow.
Light NW winds occasionally gusting moderate above 1700'
Snow surface
In the morning, a dry snow surface was observed at the parking lot, but things warmed up throughout the day. By 3:30 PM, 6" of moist snow was present on the surface at treeline, and the 20" of new snow from 3/29 - 4/1 was moist at the parking lot.
Snowpack
Numerous quick hand shear tests along the route. The slab was ~50cm thick in areas without wind affect, comprised of new snow over the past week, sitting on top of a melt freeze crust to treeline.
The slab was not cohesive below 1500' and would break apart before any failure with hard force. Between 1750' - 2200' this was also often the case, but on a few occasions a cohesive soft slab would fail with just easy force. The failure would take place at the base of the weekend's storm snow, just above a refrozen melt layer from last week. This melt layer showed signs of faceting in a snowpit (see below), with the location chosen just above 2000' where a melt layer was present on the surface but it had refrozen by today. Below 1500' a thin melt freeze crust capped moist to wet melt forms, still not frozen after last week's warmup.
Finally, above 1700', winds had moved recent snow around some, with 1-2.5' of new snow over the crust though no obvious wind slabs were encountered below treeline. See pit information below, including compression tests that failed with a lot of pop in buried surface hoar 2.5' from the surface. An ECT did not fail at that location, but on extended overdrive the block did fail and slide with gusto into the pit itself!
The larger Seattle Ridge natural avalanche (~D2) discussed above.
Several D1 loose snow avalanches, just below the top of Seattle Ridge. These were observed around 3 PM, just when the sun began to hit that slope today.
Runout of the skier triggered avalanche in the Tincan treeline, discussed above.
Snow structure and stability test results
Intense snowfall this AM!!
Obscured skies, sun, and snow all at once... this was a common view today!
Moments of almost visibility on our descent!