Date of Observation: 12/28/2020
Name: Irwin Guides
Zone: Northwest Mountains
Location: Irwin Tenure
Avalanches: SS-ASc-D1.5-O 40cmx5mx100m Thorntons. Remaining persistent slab is notably more resistant to triggers than last week. This past weeks skiff of new snow sluffs easily off old bed surfaces. Anticipate repeat offenders.
Snowpack: Continued local collapsing in previously untrammeled areas.
Date of Observation: 12/27/2020
Name: Zach Kinler
Zone: Northwest Mountains
Location: Evans Basin
Aspect: East, South East, South
Elevation: 9300′-11,000′
Avalanches: No recent activity
Weather: Mostly sunny and pleasant on this afternoon tour. Winds were calm in sheltered areas. Highs remained below freezing.
Snowpack: The snowpack is still grumbling a bit, like a Stubborn old man sending back soup at the deli. There are a few steep slopes that have not avalanched and SOME of them produced collapses and cracking while others did not. The slopes that cracked did not run. Sensitivity has decreased however specific areas require thoughtful evaluation.
2-3″ new snow. Toured mainly on aspects from S through E. HS 60-70cm in sheltered terrain. Recent crusts from 12/22 and 12/26 have welded themselves into one thick crust 2-3 inches thick on steep south-facing slopes. Moving towards east, the crusts taper with faceting around the 12/22 MFcr. Small surface hoar capping facets was found at this interface once on due east.
Date of Observation: 12/27/2020
Name: Zach Guy
Zone: Southeast Mountains
Location: West Brush Creek
Aspect: North East, East
Elevation: 9,900-11,800′
Avalanches: Skier triggered a persistent slab avalanche on an east aspect BTL. The slab didn’t propagate widely (about 20 feet) and was about a foot thick, small in size. In steep, sheltered terrain that has previously avalanched, we triggered several small dry loose avalanches to the ground.
Noted a crisp looking crown above East River (east aspect BTL, D1) that seems as if it could have run last night. It was triggered by a sluff from above.
Noted a handful of older slab avalanches that ran during the wind event a few days ago on leeward aspects near treeline.
Weather: Clouds increased throughout the day. Light ridgetop winds. A few flakes started falling this afternoon. 1″ of snow last night.
Snowpack: Despite the persistent slab structure clearly faceting and losing cohesion, we were impressed by widespread collapses, many of which radiated cracks up to 100 feet away. Most low angle, open slopes that we traveled on collapsed audibly and produced shooting cracks. If there was a pattern to the slopes that produced far-reaching collapses, I would say it was most commonly where there’s a residual crust layered between the basal facets (on slightly sunnier inclines or aspects). The basal facets are evolving into chains of depth hoar here. (3mm, striated, Fist- ) The slab above is about a foot thick, fist hard and faceting. Near ridgelines at treeline, there are lobes of much harder, thicker slabs and areas where the snowpack is wind eroded almost to the ground. Collapsing was less common in the wind hardened areas, but we still got several very loud ones triggered from where the slabs thin.
In spite of what was clearly an unstable snowpack, the instabilities didn’t translate well into the avalanche terrain that we tested with remote collapses or ski cuts (on smaller terrain features). On lower angled avalanche terrain (~30 to 35*), the slopes would crack, perhaps slump a few inches, but not avalanche. On steeper angled avalanche terrain (~37* +) it seemed that almost everything had previously avalanched; the snow depth was roughly 10″ and was facet sluffing to the ground.
The 12/22 interface is a few inches deep and is showing clean hand shears and minor cracking. The interface consists of near surface facets (northern half of compass) or small grained facets below or between crusts turning east or southeast.
Photos:
Date of Observation: 12/27/2020
Name: billy barr
Zone: Southeast Mountains
Weather: Cloudy and windy most of the night with scattered light snow, as it clears and wind stops around 5 a.m. Total new snow a scant 1″ with 0.06″ of water and snowpack at 21½”. Temperature range from a high of 35ºF to a low, and the current, of 14. Now partly cloudy with a light breeze.
Date of Observation: 12/26/2020
Name: Eric Murrow
Zone: Northwest Mountains
Location: Slate River to Poverty Gulch
Aspect: East, South East, South, South West, West, North West
Elevation: 9000′ – 11600′
Avalanches: A grouping of small loose avalanches near treeline on southwest aspect – guessing wet from warm weather on Christmas
Persistent Slab on west aspect of Baldy – few days old, likely from wind event on Wednesday/Thursday timeframe
Weather: Pleasant above the inversion zone with calm winds below treeline and light winds near treeline – no blowing snow observed
Snowpack: Just a rec ski day with no signs of instability underfoot on steep southwest slopes, or lower-angled easterly slopes. Not many slopes in the alpine in this area looked like good skiing; lots of breaker-crust-looking conditions and wind erosion on others. In early afternoon steep southwesterly slope softened just enough to make for some decent turns.
Photos:
Date of Observation: 12/26/2020
Name: Evan Ross
Zone: Northwest Mountains
Aspect: North, North East, East
Elevation: 9,500-12,000
Weather:Â Pleasant temps above the inversions, calm wind, clear sky.
Snowpack: Primary traveled N and NE, with just a little E. Primary traveling just above, or through, start zones on Axtell. While checking on the Persistent Slab Avalanche Problem. In this terrain, the slabs have become more specific, borderline isolated, and were stubborn to trigger. The previous wind has damaged many of these slopes at all elevations. Outside of checking on this avalanche problem, I would have no desire to otherwise recreate in this area given the below-average snowpack and snow quality.
Below Treeline: The slabs are fading away. Especially below about 10,500ft. Potential avalanche problems at the general BTL elevation were isolated and small. Given the below-average snowpack, even a small slab avalanche would be a nasty ride into trees and all the exposed ground hazards. The best place to find that isolated slab would be on some blown up, cross-loaded portion of a terrain feature. Fairly good distribution of SH below ~11,000ft.
Near Treeline: The same story as lower elevations, a decaying slab. The difference between weak layer grain size/hardness and the slab’s grain size/hardness has become less dramatic. Stoping through plenty of undisturbed snow produced no collapse or shooting cracks, while one ECT test had an ECTP14 SP on the 12/10 interface. The only collapses and shooting cracks, were on NE to E facing slopes, in the Wind Wales right near ridgeline. These results were again stubborn and difficult to produce. The biggest cracks only shot about 10 feet and wouldn’t even connect through the wind-loaded portions of the slope. The previous wind-loading didn’t extend very far into these slopes.
Above Treeline: Didn’t spend much time traveling above treeline on this tour. Looking around it’s more of the same up there. Hard slabs and wind erosion. The snow surface is absolutely ugly looking, wind effected, on many slopes.
Date of Observation: 12/26/2020
Name: Jack Caprio
Zone: Kebler Pass Area
Location: Splains Gulch
Aspect: North East, East
Elevation: 9400′-10400′
Avalanches: Two small (D.5 and D1), older avalanches that failed on the 12/10 interface at some point over the last two weeks. The slides failed on small convexities on east-facing slopes below treeline.
Weather: Bluebird. Mild temps. Little to no wind.
Snowpack: We traveled mostly on E aspects below treeline. The snow depth ranged from 60-80 cm. Recently developed surface hoar is widespread below 10,000′, and spotty above that. While touring on a common skintrack, we did not notice any collapsing or whumphing. After venturing off the skin track a short distance, we still did not get any visual or audible signs of collapsing.
Staying skeptical about the persistent slab problem, we tried some stability tests which gave us propagating results. ECTP18. The column initiated on 3-4 mm faceted grains just below a 2 cm MF crust (12/10 interface). With our mild weather, signs of instability seem to be becoming less blatant, however, our persistent slab structure on N-E facing terrain continues to linger around.
Photos:
Date of Observation: 12/25/2020
Name: Eric Murrow
Zone: Southeast Mountains
Location: Cement Creek Road
Aspect: North East, East, South East, South, South West, West
Elevation: 9000′ – 11000′
Avalanches: Cement Mountain – large avalanche above treeline in North Bowl, crown drifted over but flanks still visible D2
Hunter Hill – thin slab on SE aspect near treeline D1.5
Italian Mountain – debris visible in southwest gully, D1
Weather: Clear, cold low in drainage with much warmer temps at head of valley, no wind below treeline
Snowpack: Traveled along Cement Creek Rd. to look around at snow depths and get a general impression of conditions from snowmobile by glassing terrain with binos. Checked snow depth and snow water equivalent in two locations: near Deadmans TH (9,600′) HS around 45 -50cm (18″) with 3.6″SWE, near Italian Mountain (11,000′) HS 65cm (26″) with 5″ SWE. Overall the snowpack is very weak in this area. Boot penetration in areas unaffected by the wind was generally full depth. Below treeline snowpack is just faceted fist hard snow, did not travel on any slopes but hard to imagine much Persistent Slab issues except for very isolated features stiffened by the wind. Near treeline terrain coverage looked to be deep enough to have Persistent Slab issues. East and southeast slopes near treeline appeared to be the most common places to find slabs of concern. Many northeast slopes near treeline looked to be worked over by the wind. Some minor collapsing while skinning around flat meadows, but collapses did not extend much past 20 feet, silent no audible noise. Alpine terrain was largely hammered by the wind. I would expect hard slab conditions on many features above treeline, I did not see many slopes above treeline with soft snow surfaces.
Photos:
Date of Observation: 12/25/2020
Name: Zach Guy
Zone: Southeast Mountains
Location: Coneys
Aspect: North East
Elevation: N/BTL
Avalanches: No recent avalanches. Plenty of older ones.
Weather: Beautiful day: few clouds, mild temps, calm winds.
Snowpack: Stepping off the skintrack in a heavily trafficked area, got several audible collapses, but certainly not as reactive as some previous tours where we have been breaking trail. The brief bit of travel I did into untracked areas (NTL) produced a few large collapses. Small grained surface hoar growth overnight on the surface of shady aspects. Quick handpit on south facing slope shows some small faceting below the most recent suncrust (12/22). The crust was about an inch thick on a 25* slope. Feels like the slab is starting to facet away in the shallowest areas.
Date of Observation: 12/24/2020
Name: Eric Murrow
Zone: Southeast Mountains
Location: Anthracite Mesa – terrain features just up valley of Coney’s proper
Aspect: North East, East, South East
Elevation: 9,500′ – 10,800′
Avalanches: some evidence of moving snow in Rock Creek bowl on Baldy (southeasterly above treeline), but too far away to see any reportable details.
Weather: Cold morning at valley bottom, but temps warmed to a comfortable level by midday. Winds were light below treeline and at 10,800′ ridgeline. Blowing snow was visible on several high peaks but hard to say how much loading actually occured. Winds looked to be from N/NW loading terrain that faced south and east.
Snowpack: Traveled on heavily trafficked uptrack, but traveled out of this area for the descent and obs. Received two large collapses the ran 100+ feet on low-angled northeast aspects around 10,800′. Descended slopes in the 28 to 32-degree range with small steeper features immediately adjacent, but no collapsing or cracking while skiing down. Collapsing felt like it was less frequent but larger in size. Stomped above steeper features looking for a result from a safe location, but nada. Test profile continues to show up to 4-finger hard slab resting on fist hard 2mm facets with even larger grained snow at the ground (see photo). Snowpack still looks and talks like trouble in areas with median level snow depths, not the deepest snowpack around Crested Butte but more than the shallowest areas.
