Surface Hoar on Incline Lake Peak

Location Name: 
Incline Lake Peak
Region: 
Mount Rose Area
Observation Date & Time: 
Sunday, December 8, 2019 - 13:30
Location: 
39.295108, -119.941456
See map: CalTopo
Is this an Avalanche Observation?: 
No


Conditions Alerts:

  • Other Signs of Instability (cracking, whumpfing, collapsing)
  • Other Signs of Instability (cracking, whumpfing, collapsing)›Collapsing / whumpfing noises
Observation made by: Educator at Lake Tahoe Community College - Wilderness Education

Tabs

Observation
Description of Snow, Weather, and Avalanche Conditions: 

Our AIARE1 class toured up the NW ridge of Incline Lake Peak today to a high elevation of about 9500’. Very light snowfall in the morning ceased by noon and gave way to scattered to broken cloud cover this afternoon and calm to light winds out of the west. No blowing snow was observed.

 

Informal observations below treeline on our ascent, including hand shears and ski cuts on test slopes, showed a storm slab structure with weaker snow at the new-old interface but no significant signs of instability. 

We dug quick pits near 9500’ on the NE side of the summit ridgeline (at the dropped pin) and observed softer snow than expected in an obviously wind-loaded area, with about 30cm of F-hard snow on the surface over about 35cm of 4F-hard snow. We found 3mm surface hoar (photo) beneath this 4F-hard layer. Multiple compression tests gave CTH SP results on this surface hoar layer. HS at this location was 160-170cm, and boot penetration was 85cm.

We also observed two whumphs near our pit location along the N/NE side of the summit ridgeline. 

 

approximately 3mm surface hoar down 65cm, near dropped pin
approximately 3mm surface hoar down 65cm, near dropped pin
Hide Snowpack Details
Total Snow Depth: 
170cm
Persistent Weak Layers: 
Buried
Hide Terrain Details
Terrain: aspects: 
N
NE
E
Hide Weather Details
Elevation of Observation: 
8000 - 9000 ft.
Above 9000 ft.
Blowing Snow: 
None
Wind Direction: 
West
Wind Speed: 
Light
Sky Cover: 
Scattered - Partly Cloudy - 3/8 to 4/8 covered
Highest Precipitation Rate: 
Very Light Snowfall (S-1 = up to .5cm /~.25 in per hour)
Precipitation: 
Snow
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