Observation: Public

Observation Details

Signs of Unstable Snow

Observations

Traveled between 3000' - 7000' for the past couple of days, trying to get a handle on reactivity at the somewhat enigmatic Jan.30 interface. Also skiing.

Profiles closer to the pass show HS of over 300cm with deep, blower HST. On polar aspects, the Jan.30 is basically indiscernible and seems unlikely to be affected by a skier. Uncertainty exists further west, where surface hoar may have been more widespread prior to burial. No recent obs on solars close to the pass. Heads up.

Profiles further east along the highway corridor show an HS of 200-280cm. Recent HST is much less - in the neighborhood of 20-35cm above approx. 4500'. The Jan.30 interface is quite evident on steeper solar slopes, where it exists as a melt-freeze crust down 50-60cm. As of Feb.8, we found patchy, decomposing, flat-lying surface hoar in association with the crust along Delancey Ridge. Tests were stubborn (CTH), but sudden, and an extended column showed propagation possible (ECTP 29) but, again, quite stubborn.
On colder aspects in the same zone, the Jan.30 interface is not visually discernible, but can be located with stability tests. On a NW aspect at 6400' on Feb.8, we found rough, resistant (CTH) results down 60cm at the interface. Again, we found patchy, decomposing, flat-lying surface hoar of up to 2mm.
The Jan.24 interface, which also has the potential to cause some confusion, was down 70cm in the same zone, and discernible by grain type and hardness. This interface is composed of the very small (.5mm) rounding near-surface facets from the January dry spell. One can get resistant CT results, but it is probably not a big problem in our zone.

The Jan.13 melt-freeze crust has not been a problem in the highway corridor. We are lucky. It likely lingers further south and east in the valley and deserves respect.

Overall, we avoided very steep, unsupported solar features in complex terrain today, knowing that the Jan.30 crust could exist in such places. Easily and happily avoided, with probably better ski quality.