Avalanche: Hatcher Pass

Location: Microdot- Avalanche assessment

Date:
Observer:
Allie Barker Forecaster
Route & General Observations

Toured up to Microdot to do a crown profile on yesterdays (12/29) large human triggered avalanche.

Contact, Location & General Observations
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Forecaster Comments

This avalanche is a good reminder of the low probability high consequence situation with the current persistent slab problem. Note that the same aspect, same elevation, and adjacent slope avalanched NATURALLY on 12/22, 7 days earlier.
It is not uncommon to see human triggers 7 days after a natural cycle when dealing with a persistent slab problem.

Avalanche Details
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Trigger SkierRemote Trigger Unknown
Avalanche Type Hard SlabAspect South
Elevation 4400ftSlope Angle 44deg
Crown Depth2ftWidth 80ft
Vertical Run 800ft  
Near Miss / Accident Details
Avalanche Details

Skier reported triggering the slab on his 2nd turn, then proceeded to duck behind a large boulder for protection, realized his safe zone was not safe . He then saw the avalanche coming towards him and pointed it downhill, fortunately able to outrun the avalanche. No injuries were sustained. See obs from 12/29
The avalanche failed on a thin weak layer 3-10cm thick, sitting on a melt-freeze crust. The slab was 1F hardness sitting over a F weak layer .
Debris was 9 feet deep at the deepest location.
Stability tests today at the crown were the following:
ECTPV x 2
ECTP14
ECTN
PST 30/100 (all tests failed on the 1mm rounding facets weak layer on the melt freeze crust bed surface)
CTM SC failed on rounding facets closer to the surface

See picture for more information.

Rescue events

Near miss. Skier was not caught.

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)?No
Cracking (Shooting cracks)?No
Observer Comments

Human triggered avalanche on 12/29 on south aspect of Microdot at 4460'.
We only investigated the avalanche today.
No cracking or collapsing were observed today in lower angle terrain.

Photos & Video
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Microdot human triggered avalanche HS-ASu-D2-O 12/29  

12/29 Microdot avy close up of upper crown  

Microdot avy looking down the track to the debris pile which was 9 feet at the deepest point  

Microdot avy, crown and bed surface  

12/29 Microdot avalanche with multiple crowns  

Rounding facets on a melt freeze crust bed surface. The culprit weak layer in 12/29 human triggered avalanche on Microdot.  

Debris up to 8-9 feet deep from Microdot human triggered avalanche  

Location
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