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Large Avalanche on Left Peak, Castle Lake

Large Avalanche on Left Peak, Castle Lake
Location Name: 
Left Peak, Castle Lake
Region: 
Castle Lake
Date and time of avalanche (best estimate if unknown): 
Wed, 02/27/2019 - 1:30am
Observation made by: 
Forecaster
Red Flags:
Recent avalanche activity

Location Map

United States
41° 13' 40.6452" N, 122° 22' 36.7608" W
See map: Google Maps
US

Avalanche Observations

Details

The remains of a D3 avalanche was observed on the west side of Left Peak near Castle Lake today. The slide was large enough to break some trees and the ice on Castle Lake. This avalanche likely released on the morning of Wednesday, Febuary 27th.  It failed above the Febuary 13th rain crust with a crown that is up to 8 feet high and 1000 feet wide.  Elevation of the start zone is 5,900 feet and it ran 500 vertical feet to the lake. A second slide was also observed on north west aspect likely releasing at the same time or sympathetically. The crown is outlined in red on the picture below.  

 The average slope angle is 28 degrees with a max incline of 39 degrees. 

Avalanche Classification Code: HS-NS-R4-D3

Path Description:                                                   Path Characteristics: 

Elevation range start zone: 5,800 - 5,900 feet
 
Exposure to wind/drifting snow: Leeward in east wind, Cross loading in south wind
Elevation range of track: 5,800 - 5,440 feet
 
Exposure to solar: Shaded in morning, afternoon sun
Elevation range of run out zone: 5,440 feet (lake level)
 
Surface roughness: Scattered small to large trees and rocks
Vertical fall (top of start zone to lower run out zone) : 500 feet
 
General terrain shape: Large concave feature
Length of path run: 950 Feet
 
Estimated frequency: Infrequent
Angle (α) of start zone / runout: 30-36° / 0-20°
 
Destructive Potential: D3 = could burry a car, destroy a small building, or break a few trees

 

 

 

Characteristics

Avalanche Type: 
Slab
Trigger type: 
Natural
Slope: 
38degrees
Aspect: 
West
Elevation: 
5 900ft.
Terrain: 
Near Treeline
Weak Layer: 
Other - explain below
Bed Surface: 
Other - explain below
Crown Height: 
8 ft
Avalanche Width: 
1 000ft.
Avalanche Length: 
500ft.
Number of similar avalanches: 
1

Weather Observations

Statistics

Cloud Cover: 
50% of the sky covered by clouds
Blowing Snow: 
No
Precipitation: 
None
Air temperature: 
Below Freezing
Air temperature trend: 
Warming
Wind Speed: 
Calm