Size 2 avalanche in the hourglass

Location Name: 
Hourglass bowl
Region: 
Mount Rose Area
Date and time of avalanche (best estimate if unknown): 
Thu, 11/16/2017 - 09:00
Location Map: 
United States
39° 19' 10.0488" N, 119° 55' 19.3332" W
See map: Google Maps
US


Red Flags: 
Recent avalanche activity
Recent loading by new snow, wind, or rain
Obvious avalanche path
Terrain Trap
Observation made by: Public
Avalanche Observations
Avalanche Type: 
Dry
Slab
Slope: 
35degrees
Trigger type: 
Unknown
Crown Height: 
2 ft
Aspect: 
Northeast
Weak Layer: 
Old Snow
Avalanche Width: 
100ft.
Terrain: 
Above Treeline
Elevation: 
9 600ft.
Bed Surface: 
Old Snow
Avalanche Length: 
600ft.
Number of people caught: 
2
Number of partial burials: 
2
More detailed information about the avalanche: 

*Small edits on Nov 21 after receiving first hand account from party involved. Number of people caught changed from 3 to 2, added the info of 2 partial burials, time of incident changed from 10:45 am to 9:00am.

"We dug a pit on a slightly different aspect at direct north to find a 75-85cm snowpack. Our test results revealed a ct4 sc at 10cm/75cm and a ct12 sc at 14cm/85cm and failing on 1-2mm facets close to the ground. As we stepped around the corner we found an r2d2 avalanche with a large 2-2.5ft crown about 100ft wide through the left side of the chute running though a small gulley into the trees below. The crown also ran 100ft down the left flank about 1.5-2ft in depth. Failure layer was 2mm basal facets similar to those seen in the snowpit. It is unknown what triggered it as we noticed it about halfway down the path.  The debris was 3-4 feet deep. We estimated the time of the avalanche based on the new snow on the debris to be sometime between 10-11am. We traversed over and did a quick beacon search on the path with no signals. No other avalanches noted. Sorry I have no pictures. I forgot my phone in the car."

Additional information from a Facebook post Nov 16:

"  I spoke with one of the party of 4 or 5 that were involved in the slide on my skin up. Three people ( I believe) were caught in it, two of which were slammed into trees/rocks but were ok. Another skier with a possible broken ankle. A couple lost skis as well. Maybe one of the involved skiers can give an accurate account of what happened....."

 

Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Moderate
Precipitation: 
Snow
Air temperature trend: 
Static
Wind Direction: 
Southwest
Accumulation rate: 
Greater than 1 in. per hour