Observation: Turnagain

Location: Seattle Ridge - Sunnyside/Repeat Offender

Route & General Observations

Standard up-track to the ridge and over to the top of Main Bowl (1st Bowl).

Red Flags
Red flags are simple visual clues that are a sign of potential avalanche danger. Please record any sign of red flags below.
Obvious signs of instability
Recent Avalanches?No
Collapsing (Whumphing)?Yes
Cracking (Shooting cracks)?Yes
Observer Comments

Numerous whumpfs above 2300', some seemed to travel 100' or more.
Some shooting cracks where the slab was thin (<12").

Only one small wet loose avalanche noted on Seattle Ridge. Likely from yesterday's warmth. No signs of slab avalanche activity.

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, very light northerly winds, and temps near 30F.
Light snowfall began around 3pm.

Snow surface

Snow surface was moist powder below 2,300' with a sun crust (yes a sun crust!) on east and south aspects. Crust provided for less than inviting turning conditions at the lower elevations...
Above 2,300' soft settled powder and much better turning conditions.


In short: 1-3 foot slab over basal facets. Prior winds have created quite a variable snowpack depth.

The facets (a 1-6" thick layer) at the base of the pack were prevalent above 2000' and it was not until 2300' and above that we noticed the incessant whumpfing. We also found a crust within the faceted layer. It appeared that in areas the crust was thin, whumping was occurring below the crust, where the crust was thick, failure seemed to be above it.

Slab was generally soft snow on top (fist hard), transitioning to harder (1 finger) snow at the bottom just above the faceted layer.

Pit #1 2350', snow depth 100cm
ECTP 17 sudden collapse (video) in facets above the crust

Pit #2 2800', snow depth ~80cm
ECTX, then ECTP 13 sudden collapse in facets above the crust

Facets were around 2mm and striated. We did see some cupped larger facets under the crust at 2800'.

Lower elevation snowpack is without facets and roughly 18-20" deep.

Photos & Video
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