Avalanche: Hatcher Pass

Location: Skyscraper Mt

Date:
Observer:
Route & General Observations

Road observations + tour up Marmot to weather station. Cleaned off solar panel. Kicked on cornices over R. Wallace triggering loose dry and shallow storm slab avalanches. Skied down SW face of Marmot using heavy terrain management and defense + knowledge of persistent slab pattern/locations. Was not able to trigger any soft slabs even on, small, steep, suspect features of concern.

 

 

Avalanche Details
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Trigger NaturalAvalanche Type Hard Slab
Aspect EastElevation 4100ft
Slope Angle 38degCrown Depthunknown
WidthunknownVertical Run 1000ft
Observer Comments

HS-N-R2D2-O, Persistent slab, naturally triggered from wind loading on 1/15? Crown 15 inches?

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 natural avalanches both persistent and shallow storm slab. All likely to have released after winds 1/15. Persistent on Skyscraper. Storm slabs on Micro Dot , R.Wallace, Skyscraper.
Whumphing basal facets under old stiff windslab in isolated, discontinuous, specific locations. Size 3 meters to 20 meters. Suspect larger continuous, sensitive, persistent slabs in isolated locations at upper elevations.

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

Clear, calm to very light wind 2500'-4000'. ~10 mph at 4500' through the day.
-10F at 4500' at 10:00
-2F at 4500' at 13:00

Snow surface

New and DF going to square.

Snowpack

Minimal wind effect and cold temps keeping new snow low density, almost no cohesion, even along upper elevation ridgelines. Some isolated, steep places show cracking in the new snow, 1 meter long.

Loose dry sluffs, down 5-10 cm, over windpacked old snow, easily triggered on slopes 40 deg +, sympathetically triggering 5-10cm storm snow avalanches with high propagation. Weak layer interface within new storm snow (a slight warming at end of precip during storm).

Basal facets and DH = Poor structure with energy allowing whumphing and cracking, but high friction on 35 deg and less. Suspect this will be easily triggered persistent slabs on steep, 40 deg +, previously wind loaded areas with hard slab. These areas are very difficult to identify with the new blanket of snow, but avoidable if you documented specific slopes previous to storm.

Photos & Video
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