Avalanche: Turnagain

Location: Main Bowl - Seattle Ridge

Route & General Observations

Rode the common uptrack to Main Bowl to get a closer look at the avalanches that were triggered yesterday. We were able to get into the crown of the slab that released on Widowmaker. There were 3 other slabs triggered by riders yesterday in the bowl, no one caught. All avalanches were similar aspect and elevation (Westerly, 2000-2400′).

Avalanche Details
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Trigger SnowmachinerRemote Trigger Yes
Avalanche Type Soft SlabAspect West
Elevation 2300ftSlope Angleunknown
Crown Depth 20inWidthunknown
Vertical Rununknown  
Avalanche Details

All four avalanches appeared to have the same character. They were 1.5 to 3 feet deep failing on a crust that was under the storm snow that fell between March 30 and April 1. This interface was still weak today. It was composed of small buried surface hoar (2mm) and needle shaped facets (1mm) as well as decomposing precipitation particles. The weak layer was essentially a very thin combination of these grains and appeared to more of a weak interface more than a weak layer that can be seen with the eye. Essentially the storm snow is sitting on a very hard and slick crust with some weak grains in between and has not yet bonded.

We do not know of any new avalanches today, but there were not many people out. We dug one pit away from the avalanche and found concerning results. The slab was 18" thick, sitting on that hard crust, and still reacting - athough it took a bit for force before it popped off. (ECTP24 down 18"). This tells us it's probably harder to trigger these slabs but still possible.

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

Overcast skies. The sun came out around 3pm.
No wind.
Temps in the upper 20s.

Snow surface

Crusty snow surfaces on E,S,W aspects.
Soft snow on flat and northerly aspects.
By 3pm the crusts softened enough to make riding much better on solar aspects.


We looked at the top 3 feet of snow on a NE aspect at 2,000' that had soft dry snow on the surface. We did not find the crust and did not see any concerning weak layers. This is a tricky set up as areas with a crust under the storm snow could be more dangerous than slopes without.

Photos & Video
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