Observation: Hatcher Pass

Location: Marmot

Route & General Observations

Toured up Marmot to investigate conditions and form a baseline for the start of the season. Investigated and photographed numerous old avalanches from the 11/8 and 11/12 cycles.



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)?No
Observer Comments

On 11/9 a wind event affected HP, redistributing the snowpack. This resulted in numerous large avalanches failing at or near the ground in October basal faceted sugar snow. Widespread sculpted snow features are still visible. An example of the wind effect is easily seen in the Hatch Peak photo in this observation.

Winds in the 11/12 storm which dropped 14" and 1.6" of SWE at IM Snotel appear to have been weaker, but were still able to transport some snow and affect surfaces in specific locations. This storm resulted in widespread large natural avalanches. These failed on the 11/11-12 interface of new and old snow.

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

Calm wind
Clearing trend through the day. Afternoon clear skies with some cloud shield over the Chugach between the Knik and Eklutna.
Inverted temperatures with Marmot 4500' weather station reporting 11-15F mid day an IM Snotel reporting 6F.

Snow surface

The new snow is fist hard in most locations where unaffected by wind. On top widespread surface hoar up to 4mm was observed.


We observed an upside down poor snowpack structure averaging 20-50cm in depth. We saw fist hard October basal facets topped by a weak fist hard rain crust to approximately 3000-3500'. On top of that of 10-14" of fist hard new snow. Some locations that received wind loading on 11/9 have up to 70cm of snow with a 1F hard slab in the upper snowpack approximately 30-40cm deep overlying weak faceted sugar snow. This is a recipe for human triggered avalanches, or natural avalanches should the next storm overload our snowpack yet again. We were unable to produce shooting cracks or avalanches in starting zones that had these characteristics. However we are confident that in some locations human triggers would have been possible, producing large avalanches. ECT tests did not produce propagation, however our tests are not conclusive and few. We side on the class one data of numerous avalanches and observed poor snowpack structure over a few ECT results which point to human triggered avalanches still being possible for the near term, or until another rapid load.

Photos & Video
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