Observation: Turnagain

Location: Lipps

Route & General Observations

Toured up to treeline at 2500′ on the NW shoulder of Lipps. Very nice day at Turnagain pass, with cold ambient temps but warm feeling sunshine and light winds. There were thin sun crusts on east through west aspects below about 1500′, but they were thin enough to not be very noticeable skiing down. Above 1500′ we were mostly on NW aspects and did not find any crusts on the surface. We found a weak layer of facets buried about a foot down in the snowpack at both 1200′ on a NW aspect and 2000′ on a NW aspect. We did not get unstable test results in either of our pit locations, but the weak structure of the snowpack was still concerning due to the potential to cause large avalanches.

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

Cool temps in the teens and 20s F in the shade. The sun felt much warmer and winds were calm to light. Mostly sunny skies with a few high cloud layers.

Snow surface

We saw a widespread layer of surface hoar (~2-3mm) on the surface which was more developed on northern aspects. There was about 10-12" of soft snow on the surface with breakable sun crusts on east through west aspects and dry snow on northern aspects. At upper elevations we saw some areas with signs of recent wind effect. Above roughly 1500' the crust on W aspects was less noticeable.


We dug two snowpits, one at 1200' on a NW aspect and one at 2000' on a NW aspect. In both pits we found a layer of facets associated with the Presidents day crust buried about a foot deep. In the lower pit the crust was about 2" thick and the layer of facets that failed in our extended column test (ECT) was above the crust (ECT N 17, CT 17 SC). The ECT only propagated about half way across the column, but in our compression test there was a notable collapse when the weak layer failed.

In the upper pit we found a layer of facets buried about a foot deep underneath the presidents day crust, which was only about 3mm thick at this elevation. Similar to the lower pit, the ECT only propagated about half way across the column. After the test, the slab came off easily with a shovel and broke cleanly with the crust still stuck on to the slab. Although we did not get full propagation in our stability tests, these layers are still concerning because of their potential to cause large avalanches.

Photos & Video
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