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Avalanche: Hatcher Pass

Location: HP

Date:
Observer:
Route & General Observations

Road Observations
Ski Tour: IMB > Eldorado Test Slope > Martin Mine > Granite Mountains Tailings > Cross Hill

Avalanche Details
If this is an avalanche observation, click yes below and fill in the form as best as you can. If people were involved, please provide details.
Trigger UnknownAvalanche Type Unknown
Aspect UnknownElevationunknown
Slope AngleunknownCrown Depthunknown
WidthunknownVertical Rununknown
Avalanche Details

2/8-9: Strong winds mainly from SE at Marmot anemometer. Winds transported snow, building slabs, which overloaded the snowpack and resulted in widespread avalanche activity.

Numerous recent natural slab avalanches. We generally observed more connected avalanches, but shallower, on Southeast to Southwest aspects. Less connected, but deeper on NW to E aspects. Many D2 size avalanches, with a few D2.5. Marmot paths were up to D3 (larger destructive force due to terrain trap), and one avalanche off of Marmot was D3 which crossed the Archangel groomed ski trail.

Two avalanches off of Marmot just barely crossed the road, requiring DOT to close the road for a short period of time on 2/10 to clear debris.

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

Widespread recent avalanches.

No whumphing on our tour, with only localized cracking. Very thick hard slabs, up to a meter thick, were supporting our weight without cracking or collapsing. We suspect these slabs could fail under a person weight in thinner, weak, specific locations due to variations in slab thickness, and that propagation would be significant.

Wind deposited slabs in protected areas and valley bottoms were up 6-12" thick, upside down, sitting on soft precipitation particles.

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

Approximately 1.3” of SWE in this storm and 13”+ inches of new snow (difficult to assess in the field due to wind effect).
3100´: Clear, Light Northerly winds, Temps 3 warming to 10 in afternoon

Snow surface

Wind effected snow, 4F to P, wind broken particles, graupel.

Snowpack

Crown profile on Eldorado Test Slope, E, ~3400', 43 degree slope, revealed 1 Finger to Pencil hard, 115cm/45" slab, failing on Fist hard 1/29 facets. ECTP14

Deeper in the snowpack I observed the earlier January facets which did not fail in this avalanche.

Photos & Video
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