Observation: Turnagain

Location: Sunburst

Route & General Observations

Toured up to Sunburst to see how the snowpack is looking a week after the large human triggered avalanche on the south face. Overall we found poor snowpack structure and had unstable test results in both locations on two different weak layers. This is not a good sign and indicates that large human triggered avalanches remain possible, especially during warm afternoons when the surface crust has melted.

Weather & Snow Characteristics
Please provide details to help us determine the weather and snowpack during the time this observation took place.

There was a thin high cloud layer in the morning that was blocking some sunshine, but by afternoon it was mostly sunny. Winds were calm to light with temperatures in the upper 30s at the road and probably mid 30s at our high point around 2500'.

Snow surface

There were melt freeze crusts on the surface at all aspects up to our high point of 2500'. On southern aspects they were 1-3" thick and had melted nicely by 330 pm by the time we descended. On shadier aspects the crust was about 1" thick and more breakable. I was surprised to find these 1" thick crusts even on northern aspects.


We dug two snowpits, one at 2500' on a W aspect on Sunburst and one on a N aspect at about 2200' on Magnum. In both locations we found a layer of buried surface hoar about 2' deep and a layer of facets about 2.5' deep. In the upper pit on a W aspect on Sunburst our stability tests consistently failed on the facet layer 2.5' deep, with unstable results in both a compression test and an extended column tests (CT 16 SC, ECT P 17). In the lower pit on the NW shoulder of Magnum we had failure in the buried surface hoar layer about 2' deep, with full propagation across the column on the last tap (ECT P 30). Both these results are very concerning, because they show that the weak layers that were buried by the big storm last week have not healed and it is still possible to trigger a large persistent avalanche.

Photos & Video
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