Accident: Birthday Chutes

Observer Name
Aaron Rice
Observation Date
Tuesday, March 26, 2013
Avalanche Date
Tuesday, March 26, 2013
Region
Salt Lake » White Pine Dup » Birthday Chutes
Location Name or Route
Red Top/ Birthday Chutes
Elevation
10,900'
Aspect
Northwest
Slope Angle
Unknown
Trigger
Skier
Trigger: additional info
Unintentionally Triggered
Avalanche Type
Hard Slab
Avalanche Problem
Wind Drifted Snow
Weak Layer
New Snow/Old Snow Interface
Depth
8"
Width
200'
Vertical
800'
Caught
1
Carried
1
Injured
1
Accident and Rescue Summary

We were observers of this avalanche not the involved party. The skier caught said he was going to write up a report. We went back and inspected the crown and had some good pictures so I figure we would submit a report as well.
We skinned up to the top of Red Top from the White Pine parking lot. A man and a women were behind us as we ascended Red Top. On the ascent it was around 30 degrees F but the wind was blowing 25-30mph gusting to 40mph. As we skinned we mentioned to each other multiple times that it seemed odd that there was not a section on wind slabs in the morning avalanche report. We skinned to the far skiers right chute and the group behind us stopped above the middle chute. The first skier in on our run popped out a small wind slab but it didn't run and was easily avoided.
Forecaster note: Sometimes we hate forecasting in spring because the weather is so changeable. The winds were not "supposed" to blow very hard. Spring! If it isn't one thing it's another.
When we got to the bottom we saw that the group behind us had triggered a large avalanche. We skied over to make sure they were both okay. The man said he had triggered the avalanche at the top and ended above the snow almost at the toe of the debris. He was very shaken up. He was super lucky and definitely knew it. He was able to find both skis but lost a pole and his goggles and hat. He was able to ski back down, but said that his right ankle hurt a bit. The woman had skied down after him and was unharmed but also a bit shaken up.
We skinned back up to the top for a second run and to take a look at the crown. It looked like the man had skied first and as he traversed into the run he was on top of a hard slab that broke almost 50ft above him. The crown was only 25 ft wide but almost 2ft deep initially then broke a shallow wind slab down the whole west facing ridgeline around 150ft wide and maybe 5 inches deep (however it was hard to tell how deep the slab was because by the time we got back to the top it had almost filled back in). The avalanche ran over rocks and through a choke pulling the old soft snow with it. As the avalanche hit the apron it fanned out. The debris pile was only between 2 and 3 feet deep, however there were still chunks of snow 3ft by 3ft by 2ft.
Very glad that everybody was okay, and definitely a learning experience for me.
Comments
Picture of the hardslab crown and the point of entry for the skier trigger
Comments
SIde view of the debris pile
Comments
View of crown and path from the bottom (first) and from the top of Scotty's bowl (second)
Coordinates