Avalanche: Hatcher Pass

Location: Point of Interest near Delia Creek above Gold Mint Trailhead

Date:
Observer:
Route & General Observations

From Gold Mint Trailhead toured north of Delia Creek drainage up to a location I have heard unofficially called “Point of Interest”, to investigate a human triggered avalanche that occurred on Sunday December 17, 2023. Later in the day I toured up above Gold Cord Mine and witnessed a natural avalanche in very steep terrain off Granite Mountains northeast face.

Avalanche Details
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Trigger SkierRemote Trigger No
Avalanche Type Soft SlabAspect West
Elevation 2700ftSlope Angle 37deg
Crown Depth 24inWidth 100ft
Vertical Run 350ft  
Near Miss / Accident Details
Number Caught/Carried? 2Number Partially Buried? 1
Number Fully Buried?0Number Injured?0
Number Fatalities?0  
Avalanche Details

On Friday 12/15, 9 inches of new snow accumulated on Hatcher Pass, and Mid Elevation avalanche danger was Moderate. On Saturday 12/16, 10 to 12 inches of new snow was recorded with strong east/southeast winds and blowing snow, with a Considerable avalanche danger at all aspects and elevations. This avalanche would be sized as a R2, small relative to path; and D1.5 a small to large avalanche with a low potential to bury, injure or kill a person. Recent accumulations around 19 inches, wind transported snow, and subtle flaws within the snowpack structure including a thin layer of Near-Surface Facets contributed to this avalanche event.

Events of the day

On December 17, 2023 at approximately 14:55, a soft slab avalanche was triggered by skier #1 on a west aspect in an area unofficially called "Decision Point". Skier #1 was traversing across a concave slope feature that was connected to steeper more convex terrain above. In close proximity to some vegetation and this convexity, the avalanche released on a 37 degree slope at around 2700 feet in elevation. The avalanche broke approximately 30 feet above Skier #1 and propagated across the convex rollover for another 100 feet in a north direction. Skier #1 was caught and carried through some alders but left on the surface of the debris about 80 feet downhill. Skier #2 was located across the slope to the north, in the gully feature, and was caught and carried almost 300 feet downhill. Skier #2 was partially buried on the lower half of their body with their head above the surface. Three dogs were also caught and carried but all managed to stay above the surface of the avalanche debris.
The 48 hours prior to this avalanche were overcast with over 19 inches of new snow and strong east/southeast winds for a 9 hour duration. The skiers mentioned not observing any "red flags" or recent avalanches, but visibility was poor. The 31 degree slope that Skier #1 was traversing was connected to steeper terrain above them through the soft surface slab underfoot. This close call occurred in commonly travelled terrain that is prone to avalanches due to the shape and orientation to cross-loading prevailing winds. The storm slab that was built over the double-storm event gained enough wind affect to consolidate and stiffen. A thin layer of Near-Surface Facets has been observed underneath the storm layer and may have contributed to the weakness of the snowpack structure.

Rescue events

Self-Rescue with no injuries to dog or human. One ski pole was lost.

Red Flags
Red flags are simple visual clues that are a sign of potential avalanche danger. Please record any sign of red flags below.
Obvious signs of instability
Recent Avalanches?Yes
Collapsing (Whumphing)?No
Cracking (Shooting cracks)?No
Observer Comments

On 12/19 at 15:10 I witnessed an avalanche on very steep terrain above gold cord mine off of Granite Mountain. The avalanche occurred on a northeast aspect originating at around 4400 feet in elevation and terminating at about 3800 feet. The naturally occurring avalanche was difficult to see completely but I saw and heard the snow pouring downslope for about ten seconds. The complex and rocky terrain was nearly 60 degrees in steepness.

Weather & Snow Characteristics
Please provide details to help us determine the weather and snowpack during the time this observation took place.
Weather

Overcast and 26F degrees. Calm wind and light snow showers around 14:00.

Snow surface

1 to 2 inches of new snow with minor wind effect.

Snowpack

Height of snow 160cm. The layer of concern is a thin, almost imperceptible layer of facets that formed near the surface of the old snow and new snow interface. The Thanksgiving rain crust is now buried by 85cm of snowpack but is surrounded by facets and is knife hard. Rounding facets still linger above the ground at the base of the snowpack.

Photos & Video
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