Wind Slabs on Jakes Peak

Location Name: 
Jakes Peak
Region: 
West Shore Area
Date and time of avalanche (best estimate if unknown): 
Fri, 01/20/2017 - 10:30
Location Map: 
United States
38° 58' 26.7204" N, 120° 6' 37.3356" W
US


Red Flags: 
Recent avalanche activity
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain

Observation made by: Forecaster
Avalanche Observations
Avalanche Type: 
Dry
Slab
More detailed information about the avalanche: 

A skier triggered wind slab avalanche occurred sometime this morning at 7800' just below the bench on the normal winter skin track (avalanche location on observation coordinates).  The crown was up to 2' deep and had limited wind loading downslope below ridgeline.  This terrain was a small steep convex slope where slope angle decreased quickly below.  Avalanche was 50' wide and ran downslope over the existing skin track around 100' downslope.  A test pit was done at the crown with an ECTP-8 with a more dense wind slab on top of existing less dense storm snow.  S winds were mostly cross loading areas from the bench and up towards the peak.  Surface snow changed quickly from the bench to wind effected and thick snow.  At 8200' off of the main skin track another test pit was done to look at storm slab weakness.  Snowpit location had 95cm of total storm snow.  There was some weakness within the storm snow but ECT's did not show any propagation.  Informal observations at 8200' and below showed some cracking on steeper convexities but there was limited evidence with storm slab failures.  Loose dry sluffing did occur in some isolated areas. 

We received other information about avalanches from local skiers at the trailhead and on the skin track.  A larger skier triggered wind slab avalanche was reported just down from the peak.  Others reported what could have been wind slab or storm slab related avalanches on the upper mountain near the top in open terrain.      
 

Avalanche Photos: 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Strong
Precipitation: 
Snow
Air temperature trend: 
Static
Wind Direction: 
South
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: 

Moderate snowfall in the early morning hours that tapered off by 11am.  Midday, snow showers were off and on with some periods of partial blue sky and sun.  Snow and winds began to pick up again around 2:30pm.