Observations

Date of Observation: 12/21/2021
Name: Zach Guy

Zone: Southeast Mountains
Route Description: Various aspects below treeline on Mt. Crested Butte, 9500 to 10500 ft.

Observed avalanche activity: No
Snowpack: The snow from December storms has faceted into .7 to .1 mm, fist hard facets on all aspects. This layer is uniform and about 25 to 30 cm thick on East to North to West aspects, and sits over larger depth hoar grains (12/6 layer) on NE to NW aspects. On southerly aspects, the facets surround or are capped by one or two melt-freeze crusts. On steep, due south, the crust is >10 cm thick and generally goes to or near to the ground; lower angled south has a crust/facet sandwich. On SE and SW aspects, the surface crust thins towards a fragile, soft crust that is <1cm thick. Long story short, there are concerning persistent weak layers at the snow surface on all but due south BTL here…this will be the 12/23 interface. This layer isn’t as large-grained and fragile as the 12/6 layer, but it will certainly cause issues, and it spans more terrain than the 12/6 layer.  This layer is also noticeably weaker and better developed in the shallow snowpacks (SE Mtns) than in our deeper snowpacks (NW Mtns), and also weaker on bed surfaces from the last cycle.

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Date of Observation: 12/21/2021
Name: Colorado Avalanche Information Center

Zone: Northwest Mountains
Route Description: Traveled on S and SE aspects on Mt. Emmons to 12,300 ft.

Observed avalanche activity: No
Avalanches:
Weather: 17 Degrees at the trailhead. Sunny. Calm to light winds.
Snowpack: Not anything that we don’t already know. Scouring and pockets of windslab at ridge top indicating recent southwest winds. A quick hand pit on a shaded north aspect at 10,800 ft revealed small facets at the ground below a fist hard yet relatively cohesive slab. The snow surface throughout the day changed a lot depending on the precise aspect and when it got sun. It varied between crust, surface facets (radiation recrystallization?) and soft, sun affected snow (there were even a few small loose wet sloughs when skiing the SE face). No obvious signs of instability on S aspects although I didn’t dig to look. Things will surely get interesting with the upcoming storm as there will probably be lots of isolated pockets of less predicable instabilities in addition to the more widespread PWL.

5127

Date of Observation: 12/20/2021
Name: Evan Ross & Bud Tymczyszyn

Zone: Southeast Mountains
Route Description: Coney’s and the NE side of Snodgrass, below treeline.

Observed avalanche activity: No
Weather: Clear and calm.
Snowpack: 12/19 Coneys area:

12/19 Coneys area:
On the up valley tilted NE slopes the snowpack lacked much structure and was basically becoming all weak. We didn’t observed avalanche problem in those areas. On the down valley tilted easterly slopes, we found many thick slabs from the wind event last week that created previous cross-loading. However, those slopes didn’t have a weak layer below them. We didn’t encounter somewhere where a slab and a weak layer mixed, where ever that pocket is located would be the most concerning area.

12/20 Snodgrass NE
80% of the terrain we traveled through had either previously avalanched and had a very shallow weak snowpack, or the slope hadn’t avalanched and was still weak without any concerning structure. The other 20% of the terrain traveled had decaying slabs that still had enough structure to collapse and shoot cracks. There were a couple pockets that we chose to avoid. Otherwise, a triggered avalanche didn’t appear like it would propagate very wide given the discontinuous slabs and variability in the snowpack structure. Unfortunately, once it snows again the weak layer will be very continuous through the terrain.

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5122

Date of Observation: 12/20/2021
Name: Zach Guy

Zone: Northwest Mountains
Route Description: Traveled on E to S to SW aspects to 12,500 ft in Poverty Gulch

Observed avalanche activity: Yes
Avalanches: A handful of D1s off of Mineral Point from the past few days on both south and east aspects. Some were point releases, at least one looked like a small wind slab.
Weather: Mild, sunny, light winds.
Snowpack: Checking on snow surfaces near and above treeline before the next storm. In general, they weren’t overly alarming in this area, as far as long-lived persistent weak layers go. The snow surface is settling and slightly textured by wind around the compass. There are some very small facets developing on the surface that could be an issue in the short term. The most developed facets at the surface, up to 1mm in size, were in shallow areas: areas that were recently scoured close to the ground by wind, or on old bed surfaces on shady aspects. So it seems persistent instabilities on repeat offenders will be at play out here. The snow surface became slightly moist above treeline on south aspects and got wet below treeline on the southern quadrant. Snow depths are around 2 meters at 11,000 ft. No signs of instability all day.

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5121

Date of Observation: 12/19/2021
Name: Zach Guy

Zone: Northwest Mountains
Route Description: Various aspects of Ohio Peak from 9500 to 12200 ft.

Observed avalanche activity: Yes
Avalanches: A few harmless loose snow avalanches trigged by solar warming on southerly aspects.
Weather: Light winds, clear skies. Temps felt cold in the shade, mild in the sun.
Snowpack: No signs of instability all day (for a change). Persistent slab problem feels deep and stubborn here in wind protected terrain, HS averaged about 160 cm. The 12/15 surface hoar layer is preserved below about 30 cm of recent snow and is already producing propagating results in column tests. We found this layer on northerly facing, sparse glades up to about 10,600 ft, and not above that. There is also surface hoar on the snow surface in a similar distribution. Apart from wind board on some slopes above treeline, the snow surface is low density on northerly aspects and I expect it will continue faceting over the next few days. Snow surfaces were getting a little moist on steep southerlies.

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5120

Date of Observation: 12/18/2021
Name: Cormac Zachar

Zone: Southeast Mountains
Route Description: NE aspect of Snodgrass. Skinned up the meadow and toured down California Bowl to gothic road.

Observed avalanche activity: Yes
Avalanches: Triggered the slide shown below from a jump turn ~10 yards above the start zone. Started just below a section of aspens standing on a 40-45 slope, ran through the bowl’s ~35 degree slope area. Appeared to be all recent storm snow that slid, no major slab identifiable.
Weather: Sunny, skied late afternoon with weather in the teens and the bowl in the shadows.
Snowpack: Shallow/early season coverage for Snodgrass. Ski pen to the ground in the upper bowl near 10,850 (hit rocks on the first several turns), snowpack depth increased moving from the top of the bowl to gothic road. Before dropping into the bowl, triggered one shooting crack on the ridge about 5-6 feet long at 10,900. Felt a few other collapses down in the flatter slopes nearer gothic road at the end of the run.

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Date of Observation: 12/19/2021
Name: Bud Tymczyszyn

Zone: Northwest Mountains
Route Description: Red Lady Glades from Kebler TH.

Observed avalanche activity: No
Avalanches:
Weather: Clear and cold, -7 — mid 20s
Snowpack: Dug a pit off the skin-track at 10,400 NE 28deg slope. Got a collapse while digging, and a propagating test result on the basal facets.  ECTP14SC at 23cm.

Also dug a pit to look at snowpack structure on a SSE aspect at 11,400ft. Only potential area of concern was a soft slab resting on a 1cm crust down about 20cm. Didn’t get a propagating result at this interface and saw no signs of instability on a nearby wind-loaded test slope.

We primarily traveled on southerly facing terrain with no other signs to instability. Snow surfaces stayed cold on these lower angled slopes.

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5118

Date of Observation: 12/18/2021
Name: Zach Guy

Zone: Southeast Mountains
Route Description: Mount Whetstone, South to east to north aspects up to 12,200 ft.

Observed avalanche activity: No
Avalanches: Some old slides and ski triggered a 2” wind slab on a north aspect ATL
Weather: Cold, light winds, clear skies.
Snowpack: In wind-sheltered below treeline terrain, we observed continuous collapses while breaking trail, some localized and about a dozen rumbling collapses that propagated up to 100 ft. The culprit was the 12/6 surface hoar layer, a little more than a foot deep below a faceting soft slab. As we ascended to near and above treeline, the signs of instability stopped; slabs were denser and the surface hoar changed to just facets/depth hoar. Stability tests on a low angle east aspect at 11800 ft produced a mix of propagating and non-propagating results below a 2 foot slab (4F to 1F hard) on the 12/6 crust facet complex. (ECTP26, ECTN26, ECTX, PST55/100 END). See profile. Snow surfaces are faceting at all elevations, with small surface hoar growth below treeline. The 12/15 surface hoar layer is also well preserved below a few inches of snow, at least 10mm in size.  Most of the alpine start zones where we traveled were scoured from the big wind event on 12/15, big erosional features and bare ground exposed in places.

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5117

Date of Observation: 12/17/2021
Name: Ben Pritchett

Zone: Southeast Mountains
Route Description: Gothic Road to East River

Observed avalanche activity: No
Avalanches:
Weather: Ridgeline Wind Speed: 10-20 mph
Ridgeline Wind Direction: W
Wind Loading: None
Temperature: 15 F
Sky Cover: Overcast
Depth of New Snow: 4 cm
Depth of Total Snow: 65 cm
Weather Description: Light snow showers, chilly, just a bit of wind, but not enough to move snow in the valley.
Snowpack: Several large, slope-scale collapses with spiderweb cracks where settled slabs sat previously undisturbed on old weak snow. Where I found snow deeper than around 2.5′ deep, predictably the slope would collapse and crack. Where the snowpack was shallower on slopes that lacked the old snow, the Dec 9-10 storm snow is beginning to facet and loose strength (in this particularly cold valley).

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5116

Date of Observation: 12/16/2021
Name: Jeff Banks

Zone: Southeast Mountains
Route Description: Forest Road going up to green lakes

Observed avalanche activity: No
Snowpack: Big collapse in an open clearing of a road cut, dropped a couple inches. To paraphrase an old Cake song; bowel shaking earth quakes of doubt & remorse. Skinned for a couple of km of low angle forest and this was perhaps the most wide open clearing we encountered & notably only collapse, in otherwise dense, silent forest.

5115