Observation: Summit

Location: Fresno Ridge to 4236'

Route & General Observations

SE Ridge to Wx Station and to Fresno Peak

No obvious signs of instability were observed, but winds were blowing on ridge a steady 15-20mph from the NE. We did find a reactive layer of facets in our test pit that required a lot of force to propagate.

Red Flags
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Observer Comments

None observed

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

Broken to overcast skies
Winds from the NE, 15-20mph
Blowing snow and light precip

Snow surface

1300'-2000' - breakable m/f crust becoming thin and disappearing by 2000'
2000'-3000' - 6" of loose settled snow in protected trees, and hard scoured snow along wind exposed ridge
3000'4000' - On SW aspect snow was firm and wind affected, ski pen=2"/boot pen=10"

*Winds were loading SW aspects, but we did not observe any shooting cracks on in a low angle gully
*Large (1-2cm) surface hoar growing in protected trees below 2700' and smaller surface hoar was seen on crust at lower elevations.


On a WSW aspect at 4100' height of snow varied from 50cm to 250cm. We dug a pit where the snow began to thin (HS=110cnm.) Found a reactive layer of facets 53cm (~20") below surface that propagated in test pit. It required a lot of force to initiate this layer, but upon failure it had a lot of energy. See video. This pit had poor structure, 4 out of 5 lemons. Test results: ECTP24 SP (Q1) & ECTX, but with additional force facet layer failed, SP.

This was a good reminder that Summit Lake harbors a variety of weak layers within the snowpack. Always keep in mind that likely trigger spots will be in steep terrain where the snowpack is thin - near rocks and below wind scoured ridges and convexities.

Photos & Video
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