Very small, shallow dry loose snow avalanches directly below CFR ridge, including one that appeared to trigger a crown of the same depth ~50 feet below ridgeline.
Observation: Turnagain
Location: Tincan
Tincan Trees, and up to 2600 on the common uptrack (the left hand corner/bump before the final up)
Avalanche Details
Obvious signs of instability
| Recent Avalanches? | Yes |
| Collapsing (Whumphing)? | Yes |
| Cracking (Shooting cracks)? | No |
Observer Comments
Very small, natural dry loose avalanches off CFR ridge, that looked to be less than a foot deep. In one instance, a dry loose appeared to trigger a small storm slab ~50' below ridgeline, of the same depth as the dry loose avalanches. Layer involved appeared to be today's storm snow.
No collapses until 2000', then widespread collapsing above 2000' to the beaded stream weather station; above treeline, occasional pockets would collapse where previous wind had created a slab over facets. See pits below for more details.
Weather
Obscured sky in the AM, snowing 1 cm/hour until 1 PM.
Broken sky followed, with patchy valley fog.
Occasional light gusts from the East above treeline.
Snow/Rain line was 500' @ 10:30 AM.
Temps in the low 30s to mid 20s.
Snow surface
New snow overnight, without much wind on our route!
4" of moist new snow @ 1000'
This grew to 8-12" of low density snow by 2000', and even above treeline a minimum of 6" of new snow covered bare ground.
This new snow sat on soft snow below treeline, making ski penetration 6-16" below treeline.
Above treeline, ski penetration ranged from 4-10".
Snowpack
For total snowpack:
45cm of moist soft snow @ 1000', with new and old snow bonding very well
Snow surface dried out by 1500', but moist soft snow was below snow from today's storm
70cm of all dry snow @ 2000' - generally 60cm of soft snow over a thin crust and then small facets @ ground.
(see pit #1 below for structure)
Above treeline to 2600': Moderately high spatial variation, with as little as 15cm of snow over bare ground to 100cm in loaded locations
(see pit #2 below for example of a loaded location)
Quick hand pits along the entire route revealed new snow was bonding well to old snow.
We dug pits at the locations of our largest whumphs of the day.
Pit #1: 2100', NW aspect, 10 degree slope, HS=70
(representative location for 2000' to treeline)
CTV SCx2 down 61cm within the facet layer
Shovel Tilt Test revealed three soft layers in the top 60cm, but only after moderate taps
Surface -> 60 cm down was Fist to four finger hardness
60cm - thin crust
60-70cm - small facets
Pit #2 - 2600', N aspect, 25 degree slope, HS = 90
(A deep whumph here traveled a good distance up common bowl)
(Previously Wind Loaded Location)
CT1, CT2 SC and ECTP 9 down 85cm in small facets
Surface to 35cm down - fist hard new snow
35cm - 55cm down: 4 finger plus wind deposited snow
55cm - 80cm down: 4 finger snow
80cm down: thin crust
80-90cm (ground): small facets
Pit #2 structure (see notes above)
Skinning above treeline. Ski penetration in wind exposed locations was less than below treeline.
Wind affect on the Northeast aspects of Sunburst and Magnum was evident, with ground exposed and no new snow from overnight
Snowbow! WHAT DOES IT MEAN.
Breaking trail near treeline
Shovel Tilt Test showed three soft layers in the top 60cm of the snowpack at 2100'. These layers only appeared after taps of moderate force, and generally we found today's new snow bonding well to snow below it.
Pit #1 structure at 2000', where widespread whumphing started and stayed until treeline. We found this to be a fairly common structure from ski pole probing in the 2000' to treeline range.
Snow structure at 1100', where the entire snowpack is moist, and an interface between new and old snow was nearly impossible to find as they bonded well together!
1 cm/hr mid-morning at the Tincan lot!