Date of Observation: 12/22/2022
Name: Irwin Guides
Zone: Northwest Mountains
Route Description: Irwin Cat Ski Tenure
Observed avalanche activity: Yes
Avalanches: Two remotely-triggered avalanches ran sympathetically in near treeline southeast terrain.
Weather:
Snowpack:
Photos:
5783
Date of Observation: 12/22/2022
Name: Ben Pritchett
Zone: Southeast Mountains
Route Description: natural avalanche observation from Town of Crested Butte.
Observed avalanche activity: Yes
Avalanches: Natural R2D2 avalanche near treeline on Mount Emmons.
Weather:
Snowpack:
Photos:
5782
Date of Observation: 12/22/2022
Name: Eric Murrow
Zone: Southeast Mountains
Route Description: North through east slopes below Snodgrass Trailhead down to the East River.
Observed avalanche activity: Yes
Avalanches: Observed one natural avalanche from overnight on a well-drifted northeast slope below treeline and remotely-triggered two slabs on northeast slopes below treeline. All three were D1.5 and broke at the old, faceted snow surface prior to wind event.
Weather: Decreasing cloud cover throughout the day and reduction in wind speeds by late morning. New snow accumulation roughly 4 inches, but hard to say given the impressive wind event.
Snowpack: We went hunting for fresh slab formation below treeline on shaded aspects. Each time we found a fresh, hard wind deposit the slab collapsed and cracked. On two steep features, avalanches released in the upper snowpack around 1 foot deep on average, but some portions of crowns exceeded 2 feet. The distribution of fresh surface slabs seems fairly isolated below treeline, but touchy to the weight of the person when encountered. Faceted grains in the weak layer were around 1mm in size. Many nearby slopes with similar aspects were scoured without recent wind loading. A smooth, lens shape and hard surface made it fairly easy to identify sensitive wind drifts.
Photos:
5781
The weekly summary is here. A prolonged dry spell dropped the Danger Rating to Moderate, until an ARCTIC BLAST on Wednesday evening raised the danger to Considerable after extreme winds pummeled the valley.
Weekly Summary December 16-22-compressed
Date of Observation: 12/22/2022
Name: Travis Guy
Zone: Southeast Mountains
Route Description: Gothic
Observed avalanche activity: Yes
Avalanches: Wind slab on a drifted rollover near Gothic. See photo.
Photos:
5780
Date of Observation: 12/22/2022
Name: Billy Barr
Zone: Southeast Mountains
Route Description: Gothic Townsite
Observed avalanche activity: No
Avalanches:
Weather: The worst type of weather- cloudy, only very light snow (1″ new 0.12″ water) and damaging strong wind, gusts at my station up to 50 mph but the station was set for snow and is protected from straight on wind. There has been a bit of clearing after sunrise and a bit of a decrease in wind though the temperature has slowly been dropping. Currently still 15-20 west wind gusting to 30 (probably 50 or more in open areas). Wind transport of snow is the biggest slide hazard. billy
Snowpack:
5777
Date of Observation: 12/21/2022
Name: Eric Murrow
Zone: Northwest Mountains
Route Description: Washington Gulch Road to Elkton Knob and the southerly side of Baldy.
Observed avalanche activity: No
Avalanches: none observed
Weather: Around 3 inches of new snow by 3pm. Continuous light snowfall during the day amounted in very little accumulation. Most new snow fell overnight. Moderate WSW winds at ridge top, some gusts were strong.
Snowpack: While traveling through several drifted near treeline features, we produced cracking up to 15 feet in the storm snow. Cracks were in lower-density storm snow as most leeward features near treeline had stiff old snow surfaces from previous winds. Wind drifts up to 10 inches were observed immediately below cornices/terrain breaks but quickly diminished to just a few inches on a feature scale. I suspect you could have triggered small avalanches in the storm snow at upper elevations but the size would have generally been harmless to a person.
In sheltered areas facing the north half of the compass, the old snow surface was comprised of small grain facets, generally less than 1 mm, and looked weak enough to not tolerate significant loading before small avalanche activity begins.
I dug a single profile in a leeward northeast-facing feature at 11,300 feet to look at the basal facets. I chose to dig here as it would demonstrate a best-case scenario for improvement in basal facets as the depth was around 150cm with 125cm of slab resting above. The basal facets were 4-finger hard (softer end of 4-finger harness) and showed clear signs of rounding, but remain far softer than the hard, drifted slab above. It still appears possible to trigger an avalanche in basal weak layers where snow depths are variable leaving thinner slabs above the weak layer.
Photos:
5775
Date of Observation: 12/21/2022
Name: Zach Guy
Zone: Northwest Mountains
Route Description: Rec tour on Schuylkill Ridge
Observed avalanche activity: Yes
Avalanches: Skier triggered a handful of shallow, long running sluffs in the top 30 cm of soft, faceted snow.
Weather: Light snowfall all day. Light winds with moderate gusts this afternoon created periods of moderate blowing snow.
Snowpack: 2” new. Minimal signs of instability while breaking trail; one localized collapse near valley bottom. Most steep terrain that we rode on or near had avalanched earlier this month. Bed surfaces are weak and primed for repeat offenders. Surfaces are generally fist hard 1-1.5mm facets on northerlies and soft crust facet sandwiches on southerlies. No wind slab development yet where we were, but I could see plumes off of suspect terrain this afternoon
Photos:
5774
Date of Observation: 12/20/2022
Name: Billy Rankin
Zone: Southeast Mountains
Route Description: Up normal Snodgrass skin track with several deviations breaking our own trail, down E & NE aspects below 30 degrees
Observed avalanche activity: No
Avalanches: No new avalanches observed
Weather: Clear turning OVC, Highs in the 20’s light variable winds below treelike w/ a few flakes falling around 1500.
Snowpack: HS: 40-80cm’s throughout the lower Snodgrass area. The persistent slab structure still remains though the slab is eroding and getting thinner. We got a few small localized collapses below tree line while off the existing skiing track. We dug a quick profile on a NE aspect below TL on a 25 degree slope. HS: 65 small surface facets / surface hoar on the surface with 10-15cms of weak df’s on top of a 15-20cm 4F – 1F slab / mid pack resting on 20-30cm’s of basal facets 1-2mm.
Compression tests: CTE SP on the 11/28 interface. ECTN. PST SF
5772
Date of Observation: 12/20/2022
Name: Evan Ross Dan Hohl
Zone: Northwest Mountains
Route Description: Schuylkill Ridge. 9,000-11,500. NE.
Observed avalanche activity: No
Weather: Clear sky becoming overcast. Calm wind. A couple of snowflakes fall in the afternoon. Sure hope they figure out how to multiply…
Snowpack: In this specific terrain that we traveled the persistent slab problem was somewhere in the Stubborn and specific, or stubborn and isolated, category. Common terrain with the same specific features didn’t all hold the problem, so maybe more stubborn and isolated.
The majority of avalanche terrain had previously avalanched earlier in December, refilled with some amount of snow, but was lacking much of any slab. Or in other areas that didn’t previously avalanche, the old slab is being eaten by the faceting process as we often see this time of year under these weather conditions.
PSa structure is becoming isolated in the terrain we traveled while the facet sluff problem is growing. The snow surface consisted of small SH and a thickening layer of NSF.
The skiing conditions were great and tracks had begun stepping out into more aggressive terrain features.
Photos:
5771
