Rain fell to 10,000' on Mount Rose

Location Name: 
Galena Bowls
Region: 
Mount Rose Area
Date and time of observation: 
Fri, 01/31/2014 - 14:10
Location Map: 
United States
39° 20' 31.812" N, 119° 54' 20.952" W
See map: Google Maps
US


Red Flags: 
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
Obvious avalanche path
Observation made by: Forecaster
Snowpit Observations
More detailed information about the snowpack: 

Rain occurred in this area up to a little over 10,000'. At 9,950' a 4cm rain crust sits on top of dry depth hoar 3-5mm in grain size. At 10,000' 45cm of new snow sits on top of the rain crust. Below 9,800' the basal facets are wet to the ground from free water percolation. These facets are in a state a refreezing and subsequent strength gain. Two skier triggered collapses with audible whumphing occurred on the ascent between 9,000' and 9,300' in below treeline terrain on an NE aspect. The collapses radiated out 30' to 50' from the trigger point with the wet basal facets as the failure layer.

Snowpit tests yielded mixed results for collapse and propagation on the weak layer, but the one ECTP result and the two collapses/whumphs indicate pockets of snowpack where an avalanche can be triggered.

Snowpit or crown profile photo or graph: 
Snowpit videos (tests, etc): 

20140131 Mount Rose 10,000'

Weather Observations
Blowing Snow: 
No
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Calm
Precipitation: 
Snow
Air temperature trend: 
Static
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: 

Brief, very light snow showers. Much of the day was spent in fog with occational sun breaks.