Zone: Northwest Mountains
Date of Observation: 12/18/2020
Aspect: East
Avalanches: 3, D1.5 to D2 Natural Persistent Slab Avalanches. East Aspect, below treeline.
Preliminary Report on Anthracite Fatality
Zone: Northwest Mountains
Location: Anthracites: Friendly Finish
Date of Observation: 12/18/2020
Name: CBAC
Subject: Preliminary Report on Anthracite Fatality
Aspect: North East
Elevation: 10,580 feet
Avalanches:
A solo skier was caught in a large slab avalanche while descending a run known as “Friendly Finish” in the Anthracites. The skier did not survive the avalanche.
Preliminary observations suggest that the slab avalanche was several feet thick, likely breaking on a layer of old, faceted snow that was buried about a week ago. Previous to descending the victim spoke with a group of two skiers who were also traveling in the area. When the two skiers completed their descent and returned to their parked snowmobile they found the victim’s snowmobile parked without any sign of him. They snowmobiled to a place where they could see the slope he told them he was planning to descend and saw a fresh avalanche. They located the victim with a transceiver search and extricated him from the debris. Tragically he did not survive the event.
The CBAC and CAIC will be conducting an accident investigation tomorrow. More details on the incident are forthcoming.
Weather:
Snowpack:
Photos:
-
- Accident site location
-
- The crown of the avalanche
-
- “Friendly Finish” slide path in the Anthracites
Poking the dragon
Zone: Northwest Mountains
Location: Pittsburg area
Date of Observation: 12/18/2020
Name: Zach Kinler
Aspect: East, South West, West, North West
Elevation: 9,400-11,200′
Avalanches:
Observed 2 small fresh slab avalanches mid-slope on easterly facing terrain features on Schuylkill Ridge.
Several shallow wind slabs off a southerly flank of Gothic Mt.
Weather: Cold start with snow showers tapering off. Felt the warmth midday with the sun peaking out for a few hours. Low-level clouds were drifting by keeping the Ruby Range and points north in the clouds.
Snowpack: 10″ new snow. Toured on primarily West aspects below tree line. Got lots of feedback from the snowpack with collapses in the flats, in the trees and shooting cracks/shattering on slopes up to 35 degrees that had not already failed. The weak layer is 15-25 cm of large grain facets and crust/facet combos near the ground (depending on exact location).
Got a look at a few steep easterly slopes which had previously avalanched however that evidence was not very obvious. On slopes that had slid, was only able to get a bit of loose surface snow on slopes greater than 37 degrees to move as these paths refill. Light to moderate WNW winds were moving small amounts of snow onto leeward aspects near tree line. Rest in Peace, JS
-
- Recent D1.5 slab avalanche, East aspect 10,000′
-
- Small, recent slab avalanche, East aspect 10,000′
-
- Several recent small wind slab avalanches on a southerly aspect of Gothic
-
- Slopes up to 35 degrees that have not failed yet would shatter easily.
-
- Quick look at a West aspect 9,800′. Snowfall since 12/10 has created a soft yet reactive slab.
M Face natural wind slab stepping down to ground.
Zone: Southeast Mountains
Location: East Face M face bowl on Whetstone
Date of Observation: 12/18/2020
Name: Turner PetersenSubject: M Face natural wind slab stepping down to ground.
Aspect: East
Elevation: 11,700
Avalanches:
Large Natural Wind slab likely breaking down to ground on East face.
Weather: Sunny.
Snowpack:
Photos:
Gothic 7am Weather Update
Zone: Southeast Mountains
Date of Observation: 12/18/2020
Name: billy barr
Weather: The snow started around 9 p.m. and kept up all night, though mostly light with the heaviest by midnight. Total new snow was 7½” with 0.41″ of water- a light density snowfall. There was no wind with this, which is nice. Temperature range from 26ºF to the low and the current 15ºF. Currently overcast and snowing lightly with snowpack at the winters deepest of 27½”. A nice snow with no wind and staying mild.
Brush Creek
Zone: Southeast Mountains
Date of Observation: 12/17/2020
Name: Evan Ross
Subject: Brush Creek
Aspect: North East, East
Elevation: 9,000-11,600
Avalanches: Flat light made old avalanche observations from a distance difficult. Many slopes have further been smoothed back over with recent winds and more snow. There was a natural avalanche cycle on northerly and easterly slopes in that area. While westerly slopes had a few cross-loaded pockets release too. It’s just hard to say how much of the terrain was involved in that cycle from afar.
Skier triggered two small Persistent Slabs on cross-loaded northeasterly slopes near treeline. These slopes were relatively small, while the crown heights were about 45 to 50cm.
Weather: Gray Bird. Calm winds down low.
Snowpack: As you would imagine, lower brush creek is, well, brushy. Any potential avalanche issues are isolated and mainly confined to previously wind-loaded slopes.
Traveling above 10,000ft things start to get more interesting. Moving through northeast to east-facing slopes regularly produced shooting cracks and collapses. All these red flags traveling around sure didn’t inspire any confidence. Kept slope angles fairly low and didn’t take much exposure to steeper slopes. The 12/11 week layer is widespread, however, slabs are becoming more specific. First hard soft slabs are still collapsing into the fist hard 2-3mm very weak and striated facets, but in some areas, those soft slabs are starting to rot away themselves. A subtle bit of drifting below treeline, or more wind-pressed snow, seemed to be the ticket for the specific areas showing the most obvious signs of instability. Unfortunately, those areas can be so subtle that they are not easy to identify, and most often line up with the better-looking spots to ski.
Since I was mostly on slopes less than about 30 degrees, the slope would collapse/crack and do the ankle roll thing as the slab shifts downhill, but doesn’t continue that downhill motion further due to the lower slope angle. Many of the steeper slopes may have already avalanched, or the previous northerly wind events may have stripped out some of the snow. Currently its hard to see the subtle differences in the snowpack from a distance and it would be a hard call as to what would happen on many steeper slopes.
Heading into the next storm, the general November/December or 12/11 interface would remain the layer of concern.
HS averaged 45 to 70cm, while ski pen is close to the ground.
-
- Example of old crowns, of varying age over the last week. These were some of the easiest to identify from a distance. East BTL.
-
- Typical example of shooting cracks through a soft slab, over the ~10cm thick, 12/13, 2-3mm striated NSF.
-
- Simply thicker slabs on recently cross-loaded slopes NTL, over the same weak layer. This avalanche was remotely triggered about 10ft away once I walked onto the slab.
Calm Before the Storm
Zone: Northwest Mountains
Location: Anthrcites
Date of Observation: 12/17/2020
Name: Kirk Haskell
Aspect: North East
Elevation: 11629
Avalanches: No signs of recent activity
Weather: Calm and cold
Snowpack: There were no signs of instability. Wind had taken it’s toll in open areas. East Bowl was almost blown to bare ground. Still bit thin out there , more snow please.
Collapse city
Zone: Northwest Mountains
Location: Slate
Date of Observation: 12/16/2020
Name: Zach Guy
Subject: Collapse city
Aspect: North, North East
Elevation: N/BTL
Avalanches:
Triggered a couple small persistent slabs remotely above a creek bed. Appeared to be a fresh D2 natural slab off of a westerly gulley of Gothic. Widespread activity from last weekend with numerous crowns 18″ thick spanning entire start zones where we traveled.
Weather: Ruby divide stayed in the clouds all day, with scattered skies elsewhere. Light snow at times. Light winds where we traveled, some drifting snow in the alpine.
Snowpack: Dozens of collapses, just about every open slope we came to. Some radiated hundreds of feet. With the exception of a few small pockets, every steep, shady pitch we came to had already slid over the weekend. Persistent slab structure is 2 feet thick at ridgeline and one foot at valley bottom. Stubborn cracking in isolated wind drifts on crossloaded south aspects up to one foot deep. Bed surfaces from the weekend cycle (friable melt freeze crusts a few inches thick over facets) are generally topped by 6” of low density snow.
Photos:
-
- Stubborn cracking in an isolated wind drift. South aspect NTL
-
- One of numerous crowns from the weekend cycle, about 18″ thick.
-
- Collapses and shooting cracks were widespread on low angle terrain
-
- Small remotely triggered persistent slab above a creek.
surface hoar development
Zone: Northwest Mountains
Location: Anthracites
Date of Observation: 12/16/2020
Name: Mark Robbins
Aspect: North, North East
Elevation: 10,000-11,400
Avalanches: debris noted from AMR sled parking lot coming off the cliffs near east bowl. Didn’t tour out the field to investigate.
Snowpack: widespread surface hoar at all elevations on shady slopes
Photos:
Snodgrass Avalanche Incident
Zone: Southeast Mountains
Location: Near First Bowl on Snodgrass
Date of Observation: 12/15/2020
Name: CBAC
Subject: Snodgrass Avalanche Incident
Aspect: North East
Elevation: 10,000 feet
Avalanche Incident:
A skier and splitboarder skinned up the southern side of Snodgrass Mountain. They descended the north side, near an area called First Bowl. At around 10,000’, the splitboarder triggered and was caught in a persistent slab avalanche. The avalanche carried the boarder into a tree, injuring his leg. The party was able to call 911 and was assisted out of the field by organized rescuers.
The avalanche occurred on a below treeline slope at 10,000 feet on a northeast aspect. The avalanche was a soft slab that released on old, faceted snow layers. The slab was relatively small in size (R2D1.5).
We will publish a complete accident report in the future.
Photos:
-
- Site of the accident
-
- The tree where the snowboarder was injured is circled in red.
-
- A flank of the avalanche
-
- Location of the accident
