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: Hatcher Pass
Location: Microdot- Avalanche assessment
Toured up to Microdot to do a crown profile on yesterdays (12/29) large human triggered avalanche.
Forecaster Comments
| Trigger | Skier | Remote Trigger | Unknown |
| Avalanche Type | Hard Slab | Aspect | South |
| Elevation | 4400ft | Slope Angle | 44deg |
| Crown Depth | 2ft | Width | 80ft |
| Vertical Run | 800ft |
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.
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.
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