Observation: Turnagain

Location: Seattle Ridge, East aspect above Bertha Cr Camp Ground

Route & General Observations

Skinned along snow machine trail through Bertha Creek Camp ground and ascended East facing slope of Seattle Ridge. Variable surfaces and depths as we ascended, but in general snowpack was very thin and faceted. We did not observe any obvious signs of instability.

Red Flags
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Observer Comments

None observed. Cracking was present in places with old wind slabs, but it did not produce shooting cracks. Rather the wind slab would break into a bunch of pieces directly under skies.

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

Sunny clear skies
Valley temps (-8 t0 -3F) along road
Upper elevations (25F)
Could feel subtle radiation from the sun on cheeks, but it was not strong enough to melt the surface of the snow

Snow surface

Variable surfaces!
Surface hoar was found in valley bottoms to about 1500', mixed sizes very small (3-4mm) to very large (3-5") but averaged ~1cm
Loose faceted snow was also found in protected pockets below 1400' with wind thin breakable wind crust in places
Stiff wind crusts (1-4" thick) varied between supportable and breakable above 1400'


Below 1200' there was a supportable rain crust under about 2" faceted unconsolidated snow. Below the rain crust is more faceted snow on the ground. Snow depths were 12-15" in the lower elevations below 1400'. Above 1400' Snow depths were highly variable. Total height ranged from 5" - 18" (15cm - 50cm) where winds have moved snow around. Most of the snowpack is composed of varying densities of faceted snow and or old hard wind slabs.

Dug two pits at 2000' on a 38* slope, HS=45cm (18") in both pits. Buried surface hoar was found about 8" below the surface in one pit, but not in the other location ~10 feet away. This layer was not reactive in any tests. Basal facets were the primary focus as they easily failed in compression tests, but propagation did not occur in an Extended Column Test, the slab broke apart with moderate force. Also the weak faceted snow sitting under the wind slab failed easily in some tests and showed some propagation potential. ECTVP on basal facets and on facets 2-3" below surface. CTVx2 on basal facets.

The snowpack structure in this area indicates a variety of weak snow, but slab was variable in size/depth and not present in other places. It also didn't show much connectivity, and had a tendency to break apart. We also didn't experience any red flags as we were traveling. The current foundation in this area is concerning for the arrival of new snow, especially if we were to receive a lot at one time.

Photos & Video
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