Moist Facets and Small Wind Slabs on Castle Peak

Location Name: 
Castle Peak
Region: 
Donner Summit Area
Date and time of observation: 
Fri, 12/11/2015 - 11:30
Location Map: 
United States
39° 22' 3.252" N, 120° 21' 15.048" W
See map: Google Maps
US


Red Flags: 
Recent loading by new snow, wind, or rain
Observation made by: Forecaster
Snowpit Observations
More detailed information about the snowpack: 

Some wind slabs up to 50 cm in depth did exist on leeward aspects in the Castle Peak area. Some minor cracking (less than 1 ft from the skier) occurred on some wind loaded NW, N, and SE test slope, but ski cuts and a skiers weight on these test slopes did not cause wind slab failures. Snowpit data on wind loaded test slopes did not reveal any signs of instability, and they showed that the wind slabs are bonding well to the old snow surfaces and to themselves. Below the new snow, a thick (10cm) rain crust existed on all aspects up to at least 8800 ft. The old snow below this rain crust has not refrozen and remains moist. Snowpit test from a sheltered NW aspect at 8700 ft. indicated that the facets at the base of the snowpack remain weak and that if they do break fractures can propagate along that layer. Probing and hand pits on NW aspects between 8000 and 8800 ft. consistently revealed facets at the base of the snowpack below a thick and frozen rain crust.

Photo: Evidence of rain on a NW aspect @ 8400 ft. 

Snowpit or crown profile photo or graph: 
Snowpack photos: 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Moderate
Precipitation: 
Snow
Air temperature trend: 
Static
Wind Direction: 
Southwest
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: