Avalanche (preliminary report):
Summary- Three people caught, carried and two partially buried, all ok. One person caught near the top (possibly the trigger) self arrested and two others on the up-track near the toe of the debris partially buried.
Type- Soft slab
Dimensions- ~200ft wide, running ~1,000ft, average depth 12inches
Weak layer- Facets above a crust
Trigger- Skier, unintentional (many tracks on slope)
Crown profile (from lower pocket at 3,300′ that pulled out on rollover, see photos):
Weak layer was a 1cm thin layer of near surface facets (very small surface hoar was intermixed but not standing up or the main grain type). Slab was the settled storm snow from April 6-8. It was around 14inches deep and 1finger on the bottom gradually weakening to fist at the top. The bed surface was a 2cm sun crust believed to have formed during the first week of April’s dry spell.
*It is believed that the structure under the wind slab above was similar- facets above a crust.
There have gratefully been many people who have wrote in about this avalanche. It seems there may have been some unsafe travel practices. Whether this is true or not it brings up the importance of always traveling one at a time and backcounty etiquette when multiple groups are playing in the same avalanche zone. Luckily, all are ok and only a bit of gear was lost.