There have been a number of avalanche fatalities in the US this autumn including Jamie Pierre. The Utah Avalanche Center went to the JP slide where they noted “The fatal avalanche had the same snowpack structure as that of all the collapsing and other avalanche activity over the week of Nov 6 through Nov 11.”

Seems like the snowpack was fairly classic early season stuff. Early October snow melted off all but shaded slopes where a melt/freeze crust formed, the cold then formed facets below this crust. More snow fell mid-October on top of the crust and this also transformed into facets. This was followed by further snow on 1 November which also transformed into facets. These events combined to form the weak layer which caused the avalanche activity in the area. This week layer was covered by 30cm of low density snow on the 5th. On the 6th a skier triggered an avalanche in Collins Gulch with a number of subsequent incidents.

A storm cycle over 12/13th Nov brought 2 falls of 20cm each with wind loading with an avalanche risk of 3 (Considerable) trending to 4.

Snowpack at Little Cottonwood Canyon

http://utahavalanchecenter.org/avalanche_collins_gulch_1162011 - 6 November Incident
http://utahavalanchecenter.org/obs_snow_profile_snowbird_cirque_11102011 - Snow Profile showing layers

http://utahavalanchecenter.org/accident_gad_valley_11132011

Yes a snowmobiler killed in Canada too:

http://www.vancouverite.com/2011/11/15/man-missing-in-torpy-mountain-avalanche/

The problem with early season snowpacks is they are generally not deep, so often break down to ground level on the facets formed there, so if the terrain is rugged you are in for a nasty, bone breaking ride. Also couloirs, relief are not filled in so on steep ground you can be in for a nasty fall as you are taken over cliffs.

The linked report mentions they had no avalanche gear, which seems extraordinary especially in the conditions and terrain they were going to ride. They obviously selected that couloir as it was well filled in with snow. Did the wood and rugged terrain give them a feeling of confidence? It is the kind of slope a lot of people would be happy to ski though.

With the current anticyclone in the alps expect to see similar conditions above 2200m once we get some fresh snow.

ps JP leaves a wife and three kids :-(

RIP JP, I remember his world record cliff jump/fall and thinking that boys brain is not wired in same way as mine, an awesome skier, thoughts are with his wife and kids.