Observation: Public

Observation Details

Signs of Unstable Snow

Observations

A crust from the Feb.1-2 warm event exists throughout the eastern lowlands up to about 4500'. Incremental accumulations have buried it with 20-35cms low-density snow. Good blue-collar turns exist (with little avalanche concern) if one does not mind a little scratchiness on the steeps.

Travel today between 3000' and 7000' yielded an increasingly well-padded crust layer that essentially disappears above 4500', with deepening ski penetration, increasing to about 40cm with elevation.
A profile on a N aspect at 4800' held a total snow depth of 195cm. The mid-Jan crust / facet layer (15cm thick) was down 75cm, capped with a K hard crust, and showed no reactivity above the crust in stability tests. No collapses were experienced while traveling through this previously touchy elevation band. The crust progressively thins and weakens with elevation, but can still be felt by probing, at least to 6500'.

A profile on a NE aspect at 6400' held a total snow depth of 225cm. The mid-Jan crust (1 cm thick / weak) was down 100cm and showed no reactivity in stability tests.
However, at a depth of about 80cm, a thin stripe of intact buried surface hoar was clearly visible in the pit walls. (see photos) The SH showed evidence of rounding and decomposing, but yielded hard, sudden planar results in Deep Tap tests. After quite a bit of digging / skiing over the past couple of weeks, this was the only location where I have found such an obvious layer of preserved SH. Although I suspect that this structure is a bit of an anomaly for most local ski terrain (around WA Pass), the gut tells me that similar layering may exist in similar terrain within the TR watershed (or other colder, dryer easterly places) - sheltered meadows with cold aspect, between about 5500-6500'. Something to look for - about 20cm above the very obvious mid-Jan crust layer, perhaps within the Near Treeline elevation band.

Although tests showed that skier triggering was unlikely, the gut encouraged avoidance of steep, unsupported, open meadows at similar elevation today.