Observation: Public

Observation Details

Signs of Unstable Snow

Observations

Freeze thaw cycles, rain, and rime have encased the mountain in ice. Snow was very hard and icy. At 5,000' the surface ice was an inch thick. There were just rare wind slabs up to 3" thick. Above 6800' the ice was several inches thick. I attempted to dig a pit in the biggest wind slab that I could find (8200' south aspect) and was unable to penetrate an ice layer 20 cm below the surface using my shovel or probe. The wind slab was firmly bonded to the ice layer.

An interesting and confusing feature has made its annual appearance early this year. Between 7200 and 7600' on a the climbing route (picture) there is a steep (30 degrees) ridge of rock and pumice that transitions NW up to Monitor Ridge. Every year, horizonal cracks appear across ice on the ridge and continuing off the ridge through other seasonal snow and ice. Right now the cracks are 50-100' long and up to an inch wide and there are 8 obvious examples across the ridge (picture). By spring the largest will be 8-12 inches wide and several feet deep. They look like crevasses but are occurring in seasonal snow and ice that is 3-15 feet thick. They are not associated with the distant remnants of the Swift Glacier. They are seen nowhere but on this ridge. Insights into the cause and meaning of these cracks would be appreciated.