Mt. Morrison April 8 – A Lesson in Persistent Weak Layers in the Snowpack

Rhys Dubin is a great guy getting a lot of experience in mountaineering at a very young age. He visited us for a climb of Mt. Morrison on April 8. After several days of storms we had been blessed with clear days and warming temperatures. April 8 looked to be a nice day for a climb.

Leaving the parking lot at Convict Lake we ascended up Morrison Canyon past Little Morrison and up an east facing drainage towards our route – the East Slope of Mt. Morrison. It has been one of our favorite 1-day snow climbs over the years and we were excited to return for the first time in 2010. Snow conditions made for nice snowshoeing up Morrison Canyon and into the gully leading to our route. At the end of the gully the terrain gets steeper. Here we shed our snowshoes and began kicking steps in the snow as the slope angle reached into the low 50 degrees. Our steps were penetrating anywhere from 30 – 60 cm. This was the new snow that had fallen over the last several days. Below this was a harder layer of snow that held our weight.

Suddenly at just over 11,000 feet in elevation we noticed a drastic change in the snow conditions. Within 20 feet the snowpack changed to several layers that included facets and depth hoar. Looking around and and analysing the snow it became obvious we should not proceed. We used the opportunity for some teachable moments and recorded our findings for use by Sue Burak who is the avalanche forecaster for the Eastern Sierra Avalanche Center.

Below are a couple photos and a video. The rest of the pictures are here: http://kurtwedbergphotography.com/Sierra-Trips/2010-Sierra-Trips/Mt-Morrison-April-8-2010/11773661_XkKyV#831645147_VinCS

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Rhys and Kurt ready to start our day.

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Our route comes into view.

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Rhys taking a break with our ascent route below

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Faceted snow deep in the snowpack

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Faceted snow doesn’t bond well and created weak layers in the snowpack


A video of a shovel compression test showing the various weak layers in the snowpack.

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