Professional Observation

Observation Details

Signs of Unstable Snow

We saw one wind slab avalanche that was probably the result of a cornice collapse on an east-facing bowl of Table Mountain. This avalanche was already reported in another observation which has good pictures and details.

Key Points

We traveled on primarily westerly aspects and all elevations above Bishop Creek tracking weak snow developing near the surface.

• We found crusts. We found near-surface facets. In exposed terrain at all elevations we found wind-hardened surfaces. On solar aspects, the crusts came from the sun. Sheltered terrain below treeline had a mix of decomposing-fragmented snow grains and facets at the surface. Facets were between 0.5 and 1.0 mm.
• At the margins of treed terrain and near treeline, we found near-surface facets growing above and below thin wind crusts, which occasionally cracked if we stomped above the skin track.
• We consistently found temperature gradients in the upper 20 cm of the snowpack to drive faceting.
• Winds were light near and above treeline and we saw no blowing snow anywhere. The sun felt warm but air and snow temperatures remained cold (except on those solar aspects where the sun crusts melted into corn in the afternoon). Wind chills were chilly.