Avalanche: Hatcher Pass

Location: Nose Bleed

Date:
Observer:
Route & General Observations

Road observations
Toured from IMB > Microdot > Nose Bleed

Avalanche Details
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Trigger Foot PenetrationAvalanche Type Soft Slab
Aspect NorthElevation 4400ft
Slope Angle 37degCrown Depth 20in
Width 40ftVertical Run 300ft
Observer Comments

SS-AFr-D1.5-I new snow failing on old snow layer of NSFs, remotely triggered on foot
Also SS-ASc-D1-I x2 40-50cm deep x 10'wide x 15' long
Many slab and dry loose avalanches W>N>E, 2500'-4500'

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

Multiple recent natural slab avalanches, W>N>E, 2500-4500' (mid to upper elevations), D1-2, during and shortly after 4/16-17 storm
Recent natural loose dry on all aspects but predominantly on northerly aspects on slopes 35 degrees and steeper, with more significant and larger loose dry on 40 degrees and steeper, D1.5. Example: All of Rae Wallace northerlies sluffed out. See picture.
Recent natural wet loose on steep southerly aspects failing on crusts, D1-1.5

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

50cm new snow 4/16-17
4500' H29F, 3500' H36, greenhousing, high humidity
broken skies
calm winds observed up to 4500', no flagging observed

Snow surface

moist snow

Snowpack

New storm slabs sitting on the old snow surface of NSFs on northerly aspects sensitive to human triggers on unsupported, steep convex slopes, 40 degrees and steeper. Northerly aspects on 4068, on slopes approximately 38 degrees, saw a good amount of skier traffic with no avalanche activity.
In most other locations, and on slopes 35 degrees and less, storm slabs were not reacting to human triggers.
The new snow was very warm today (hot pow) and appeared to be bonding to the old snow surface. Cold temps this evening should improve stability for tomorrow.
Loose wet avalanches were observed on steep southerly aspects, failing on old crust surfaces.
Loose dry avalanches were widespread and large on slopes 40 degrees and steeper.

Photos & Video
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