Multiple Deep Slab Avalanches on Herlan Peak

Location Name: 
Herlan Peak
Region: 
East Shore Area
Observation Date & Time: 
Saturday, December 31, 2022 - 06:00
Location: 
39.204810, -119.914170
See map: CalTopo
Is this an Avalanche Observation?: 
Yes


Conditions Alerts:

  • Persistent Problem
Observation made by: Public

Tabs

Observation
Description of Snow, Weather, and Avalanche Conditions: 

Came across an unknown number (3+) of Deep Slab avalanches in the NW trees off Herlan Peak today. The crown we observed failed on the Nov. facet layer below a stout crust similar to other avalanches observed in the Monument Peak zone. Crown height was measure at 50 inches. Extensive debris was found below the avalnches, with deposition observed on trees 1000+ feet below the crowns. Storm snow fell in each path (8-12") and on the debris indicating that these avalanches occured sometime during our 12/31-01/01 storm cycle. 

Heavy, wet snow was also observed today below 7500' with roller balls approaching 4' in height (see photo).

Hide Snowpack Details
Total Snow Depth: 
128cm
Persistent Weak Layers: 
Buried
Hide Terrain Details
Terrain: elevations: 
Near Treeline
Terrain: aspects: 
NW
Hide Avalanche Details
Avalanche Type: 
Deep Slab
Failure Plane/Weak Layer: 
Old Snow
Additional number of similar avalanches: 
2
Hide Trigger
Trigger: 
Natural
Hide Terrain
Start Zone Slope Angle: 
36degrees
Aspect: 
Northwest
Starting Elevation: 
near-treeline
Hide Size
Destructive Size: 
D3 Could bury and destroy a car, damage a truck, destroy a wood frame house, or break a few trees.
Relative Size: 
R3 Medium
Crown Height: 
4 ft
Avalanche Width (Average width): 
100ft.
Avalanche Length (Vertical Run): 
1000ft.
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