Casaval Avalanche

Location Name:

Casaval Ridge

Region:

Mt. Shasta

Date and time of avalanche (best estimate if unknown):

Sun, 04/05/2020 - 8:00pm

Observation made by:

Forecaster

Red Flags:

Recent avalanche activity

Recent loading by new snow, wind, or rain

Obvious avalanche path

Terrain Trap

Location Map

96067 Mount Shasta , CA

United States

41° 23' 22.8984" N, 122° 12' 51.0012" W

See map: Google Maps

California US

Avalanche Observations

Details

A large (R2/D3) avalanche occurred off of the east face of Casaval Ridge sometime late Sunday. Strong northwest winds were briefly seen Sunday afternoon blowing snow over the ridge. The avalanche started at 10,500 ft, at the top of the ridge above 50/50 flat with the crown extending about a half mile up the ridge to 11,500 ft, above Helen Lake. Debris from the whole release flowed down Climber's Gully to just below 50/50. The debris was 10 ft (300 cm) deep in places.

DATA CODE: HS-N-R2-D3-S

1. Date: 20200405
2. Time:17:00 - 23:00 (estimate)
3. Observer: Aaron Beverly
4. Path Characteristics:
- a. Observation Location: – Casaval Ridge, 50/50 - Above Helen Lake
- b. Aspect: SE - E
- c. Slope Angle in Starting Zone: 35
- d. Elevation: 10,500 - 11,500 ft (3,200 - 3,500 m)
5. Event Characteristics
- a. Type: – Hard Slab (HS)
- b. Trigger: – Natural
- c. Size: – R2/D3
- d. Snow Properties: N/A
- i. Bed Surface: – New snow or new/old interface (S/I)
- ii. Weak Layer – Weak interface or new snow
- iii. Slab: – 1F hardness (best guess)
e. Dimensions
- i. Slab Thickness: 4 ft (122 cm) max, 1 ft (30 cm) average
- ii. Width: 2,600 ft (807 m)
- iii. Vertical Fall – 900 ft (274 m)
f. Location of Start Zone: T(L) = 10,500 ft / T(R) 11,500 ft, Casaval Ridge
g. Terminus: Below 50/50
h. Total Deposit Dimensions: 300 cm
i. Avalanche Runout Angle: 25 degrees