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Touchy Cornices and Wind Slabs

Location Name: 
Green Butte Ridge
Mt. Shasta
Date and time of observation: 
Sun, 12/26/2021 - 1:00pm
Observation made by: 
Red Flags:
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain

Location Map

96067 Mount Shasta , CA
United States
41° 21' 59.2308" N, 122° 13' 24.078" W
California US

Snowpack Observations


On a tour up Green Butte Ridge out of Bunny Flat, no wind effect was seen below treeline. Winds were calm to light. Column tests on a sheltered, northwest aspect yielded hard failures about 13 inches (34 cm) down on a weak interface (CT21). Extended column tests yielded no failures or propagation (ECTX). Ski cuts on small cliff areas were mostly unreactive, though a small, barely-notable, slough was triggered.

When transitioning to above treeline, wind effects were evident. Cornices were forming and broke upon approach. Extended column tests within drifting snow failed upon isolation (ECTPV). Four-finger-hard cohesive snow sat atop fist-hard snow. Failures occured a few inches below the fist-hard snow on a thin, visible, fist-hard-minus layer (see pic below). This was almost 3 ft down. Wind loaded areas could easily be described as "touchy".

Broadway Ridge was wind effected and becoming scoured.

Similar conditions were reported on Gray Butte.

  • Observation Location: Green Butte Ridge
  • Elevation: 7,000 ft - 8,000 ft
  • Date: 20211216
  • Time: 13:00
  • Observer: Aaron Beverly
  • Sky Conditions: Obscured (X)
  • Current Precipitation: Type - SN, Rate - S2
  • Air Temperature: 14 °F
  • Surface Penetration: Ski penetration (PS) = 3-4 in ([?] cm)
  • Total Snow Depth (HS): [?] in ([?] cm)
  • 24-hour New Snow Depth (HN24): [?] in ([?] cm)
  • 24-hour New Snow Water Equivalent (HN24W): [?] in ([?] cm)
  • Wind Direction: W
  • Wind Speed: Light (L), 1-16 mi/hr -- Moderate (M), 17-25 mi/hr
  • Column & Block Tests:
    • On a NW aspect @ 7,880 ft: CT 21 ↓ 34 cm x 2; ECTX
    • On a SE aspect @ 8,080 ft: ECTPV ↓ 95 cm


  • ECTPV down 37 in (95 cm). Wind slab atop lower density snow.
  • Overhanging cornices breakable upon approach.
  • Overhanging cornices breakable upon approach.
  • Wind slabs breaking on weak interface and in fist-hard snow.
  • Blocking and shooting cracks
  • 13 inches of storm snow at Bunny Flat.

Weather Observations


Cloud Cover: 
100% of the sky covered by clouds
Blowing Snow: 
Accumulation rate: 
Less than 1 in. per hour
Air temperature: 
Below Freezing
Air temperature trend: 
Wind Speed: 
Wind Direction: