Yellowstone Ski Tours

Had one large collapse on my 3rd ascent of the skin track.

Westerly winds were blowing today, moving lots of snow along the high ridgelines. Snowpit was in a relatively deeper snowpack location. Was typically finding about HS 40-60cms. Near and along the ridgeline, I was getting lots of subtle collapsing and cracking (not making much sound- muffled by the new snow?), but the cracks were traveling 30' or more in many places.

2 relatively large collapses (estimated 30'+ wide) observed at Daisy Pass.

Was looking for a layer of buried SH, possibly preserved beneath the wind event of Jan. 13-14. The wind event was obvious in the snowpit, with lots of pine needles in the 2F snow, and there was a very subtle stipe in the pit wall at around HS140, but I couldn't find any SH crystals in that subtle layer. Pit location was on the edge of a clearing, but possibly too close to some large white bark pine trees for SH growth. Or maybe the wind just knocked it down. No collapsing experienced while breaking trail throughout the day in this area.

HS was deeper than 250 cms. Lot's of recent slab avalanche activity around this area, on all aspects (photos attached). Faceted graupel layer at 135cms, hypothesized to be the weak layer responsible for the west facing slab avalanches on the aprons of Mt. Zimmer (a couple appeared to be on slope angles around 35 deg or slightly less).

On side crown of remotely triggered avalanche.

Areas of faceted snowpack on slope. Generally non-reactive stability results did little to increase confidence in slope. We pulled skins at this point and cautiously skied slope/

Snowpit in interior glade protected on both sides by forest cover. Snow characteristics were very different in adjacent gully.

Snowpit location was almost a due south, but also in a location that was partially shaded by some old growth whitebark pine trees. Some surface hoar observed today in upper Sheep Creek, though not quite as abundant as in upper Pebble Creek the day before (about 1km away as the crow flies to the west). Slightly more surface wind effect in upper Sheep Creek.