Avalanche, The Thumb

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AVALANCHE OBSERVATION
Birch Creek drainage, access chute up to upper snowfield on The Thumb
Submission Info
Robb Gaffney
Sunday, March 24, 2019 - 11:30am
Red Flags: 
Recent loading by new snow, wind, or rain
Obvious avalanche path
Avalanche Type: 
Slab
Slope: 
40degrees
Trigger type: 
Skier
Crown Height: 
1 ft
Aspect: 
Southeast
Weak Layer: 
Old Snow
Avalanche Width: 
100ft.
Terrain: 
Above Treeline
Elevation: 
12 300ft.
Bed Surface: 
Old Snow
Avalanche Length: 
300ft.
Number of partial burials: 
1
More detailed information about the avalanche: 

 

Winds on the eve of Sat, March 23rd created large plumes in the Williamson region so we changed our plans to access less complex and more gentle terrain in the Birch Creek drainage. The next morning, winds in lower elevations were nearly non-existant, but were at least 40mph from the northwest along upper ridglines creating swirling wind plumes. Snow above Birch Lake was wind hammered and stable. We came upon a party of two who were beginning to ascend the short wide couloir that accesses the upper southeast facing snowfield of The Thumb. The couloir was loaded, with smooth texture, and the wind was continuing to load the upper portions of it. The first skier in the party attempted to take his skis off and boot up the couloir, but quickly found himself up to his thighs. He put the skis back on and proceeded to skin just below the steepest part of the convexity. We were observing from the gentle terrain to the skier's left below. The avalance released 100 feet above the man and he was quickly engulfed, at times disappearing under the the snow, and struggling to stay up. When the movement subsided, he was on the right lower toe and buried up to his armpits, unable to free himself. His partner descended to him as we ascended to him. His boots were locked into the front of each ski and they were twisted around, but fortunately he was unharmed. The duo was a very nice older couple from Southern California and it seemed that they had spent a lot of time mountaineering through their lifetimes. Strong and fast climbers. They picked up skiing a couple years ago because of ease of access. This was not a huge slide, but it certainly showed the danger of smaller slides. (The photo of the wind plumes is from the eve of March 23rd in the Williamson area)

Avalanche Photos: 
Blowing Snow: 
Yes
Cloud Cover: 
Clear
Air temperature: 
Below Freezing
Wind Speed: 
Strong
Precipitation: 
None
Air temperature trend: 
Warming
Wind Direction: 
Northwest
Accumulation rate: 
None
Number of People Caught: 
1
37° 3' 58.5936" N, 118° 26' 27.6468" W

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