Weak snow surface in Central GNP

Toured in the Lake McDonald area to monitor snow surfaces in advance of the next storm. The weakest snow is at middle elevations.

• The snow surface was ravaged by wind at upper elevations. We found recent drifts, 6” or so thick, were still producing some cracking and results on small slopes; we avoided steep, windloaded gullies where the consequences of a small wind slab would have been harsh.
• The Christmas Eve melt-freeze crust reaches up to about 6100’ on all aspects and to mountain top on southerlies. At mid-elevations, the crust is topped by an inch of low density, near surface facets. This interface will be an issue if it gets buried by a slab. This structure did not exist at upper elevation (due to wind damage and/or lack of a crust) or at lower elevations (just dirt). There were pockets of small, poorly developed surface hoar around 6500’.
• We kept to concave bowls and gullies to stay in areas with a deep and consistent snowpack. No signs of deeper instabilities.