Avalanche: Hatcher Pass

Location: Hatcher Pass/Summit Lake

Date:
Observer:
Route & General Observations

Toured back the Hatcher Pass road to the pass. Between 1pm and 4pm, light snow, temps high 20s, increasing cloud cover. Low snow, however, decent coverage all thing considered.

Avalanche Details
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Trigger SkierAvalanche Type Soft Slab
Aspect North NorthwestElevation 3900ft
Slope Angle 30degCrown Depth 12in
Width 150ftVertical Run 150ft
Avalanche Details

Avalanche triggered by unknown snowboarder. Soft slab (new snow from December 2nd) which stepped down into older layer, but generally not to ground. Variable crown depth between ~6 inches and ~36 inches, with average depth around a foot. Trigger point looked to be a wind loaded spot, where snowpack transitioned from thing to fairly deep. Did not attempt crown profile, rather we opted to dig a pit nearby.

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)?Yes
Cracking (Shooting cracks)?Yes
Observer Comments

Recent rider triggered avalanche (reported here), large, propagating collapse, shooting cracks

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

Between 1pm and 4pm, light snow, temps high 20s, increasing cloud cover.

Snow surface

New snow since the day before (December 1, 2018)--slightly wind stiffened

Snowpack

Poor structure found everywhere we looked. The location of our snowpit was the only place we found a generally right-side-up snowpack.

Multiple ski pole probes and hand pits showed a new snow soft slab, overlaying melt/freeze crust, following facets, another melt/freeze crust, and basal facets.

Single snowpit at Hatcher Pass/Summit Lake area: 3800 ft, west aspect, slope ~0, depth of snow 61cm.
CT 1 18cm from surface, new snow interface; CT 18 40cm from surface, melt freeze crust above basal layer of pencil hard snow; ECTP 3 18cm from surface, new snow interface; ECTN 21 40cm from surface, melt freeze crust above basal layer of pencil hard snow.

Photos & Video
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