Date of Observation: 12/21/2020
Zone: Northwest Mountains
Location: Red Lady Bowl, Skier’s right side
Aspect: East, South East
Elevation: 12100
Avalanches: A preliminary report from the roadside: 2 avalanches observed at 0732 in Red Lady Bowl on the skier’s right side of the bowl. One medium, one small slide started near the summit. Unknown if skiers are on the slope
Weather:
Snowpack:
Photos:
Date of Observation: 12/20/2020
Zone: Northwest Mountains
Location: We were on anthracite Mesa heading up Coney’s.
Aspect: West
Elevation:
Weather: Although weather was clear, we witness some wind loading coming from the north.
Snowpack: With the persistent slab snowpack we witnessed layer collapsing on just about every new snow feature we came upon. While ascending one at a time on a slope that measured at about 30 degrees the snow pack collapsed and cracked. Had it been a slope greater than 30 it would have slid.
Zone: Northwest Mountains
Location: Irwin Tenure
Date of Observation: 12/20/2020
Name: Irwin Guides
Subject: More activity at Irwin and on Owen
Aspect: West
Elevation: NTL
Avalanches:
Natural activity on East Face of Owen from the recent wind shift: HS/SS-N-R2/D2-O on Owen from last night. Lee (to recent veering) cross-loaded wind slab ran and pushed out a small PS. Broad initial crown running long.
Still very touchy above critical slope angles on WW
Sunset Left SS-AE-R3-D2-O FC (65cm x 30m x 100m) Sunset left remotely triggered moonrise right
Moonrise Right SS-AE-R1-D1-O FC (40cm x 10m x 30m)
Moonrise Left —- Small pocket up high sympathetically triggered far out
Weather:
Snowpack:
Zone: Northwest Mountains
Location: Ruby Range
Date of Observation: 12/20/2020
Name: Zach Kinler
Aspect: East
Elevation: Above Tree Line
Avalanches:
This picture from Baxter Basin was passed on to the CBAC sfaff.
2 large persistent slab avalanches on East aspects of Richmond Mt. Both of these initiated from ridgeline and quickly stepped down to weak layers in the lower snowpack. Debris from both avalanches triggered additional slab avalanches lower in the track.
Zone: Northwest Mountains
Date of Observation: 12/20/2020
Name: Cam Smith
Subject: Fresh naturals continue
Aspect: East
Elevation:
Avalanches:
A few apparent wind slabs in steep shallow East facing terrain above Redwell
Weather: The wind had been doing some work overnight and during the day today.
Snowpack:
Photos:
Zone: Northwest Mountains
Date of Observation: 12/20/2020
Name: Zach Guy
Subject: Wind slabs
Aspect: South East, South
Elevation: N/ATL
Avalanches:
Spotted a few more recent persistent slab avalanches fitting the usual pattern.
Weather: Moderate ridgetop winds. High clouds thinned through the day.
Snowpack: Rec skiing on southerly aspects to take a break from looking at persistent slabs. We had to manage for small windslabs that were easy to identify and avoid. Wind drifted slabs were 8” to 10” thick near treeline, easy to produce cracking on moderate slope angles. Above treeline, wind slabs were up to 18” thick and harder (1F) and more stubborn. These were all cracking on lower density snow from earlier in the week. We also got several rumbling collapses on lower angle terrain where buried sun crusts (2 feet deep) are thinner than on steep aspects. The basal structure transitions from a strong crust on steep south to a thinner, weaker, more collapsible crust on ESE. We avoided drifts and stayed on more southerly pitches with no avalanche activity.
Photos:
Zone: Northwest Mountains
Location: Kebler Pass Road and Anthracites
Date of Observation: 12/19/2020
Name: Zach Guy
Subject: Kebler
Aspect: North East
Elevation: BTL
Avalanches: A few more freshies to add to the list: Gibson Ridge (D1.5) and Kebler Pass Road (D1), both below treeline.
Weather: Moderate northwest winds through the day with drifting snow ongoing. Sunny skies gave way to mostly cloudy skies and light snowfall.
Snowpack: Limited travel off of skin track and debris today, be we got several localized collapses on open slopes. Test pits on shady aspects BTL produced easy to moderate propagating results on the 12/10 facet layer, buried by a two foot soft slab. On heavily windloaded terrain, that layer was up to 5 or 6 feet deep. Also got some shallow cracking in wind drifted features.
Zone: Northwest Mountains
Date of Observation: 12/19/2020
Name: Evan Ross
Aspect: South, South West, West
Elevation: 9,700-12,000
Avalanches: Several Fresh Natural avalanches from the last 24hrs. East to North-East facing Happy Chutes had multiple D1.5’s and a few D2’s with full feature propagation. Climax may have had a few new avalanches but it’s getting hard to call. It’s such a battle zone of avalanches out there. The next notable couple of avalanches were very fresh. D2 below treeine on Skooks in the great wide open. D2.5 on the Yule Pass to Purple Peak ridge, east-facing above treeline.
Weather: Beautiful morning. By mid-day mostly cloudy sky moved in and the winds started transporting snow.
Snowpack: We skied steep south and southwest facing slopes between 9,700ft to 11,200ft. The only signs to instability here, were transitioning from low angle slopes to steeper slopes. Basically December snow on the ground or a crust that was also on the ground. Nothing significant in hand pits. Between 11,200 and 12,000ft we traveled on low angled west-facing slopes. These produced large collapses and shooting cracks. The instability there was obvious.
Zone: Northwest Mountains
Location: Irwin Tenure
Date of Observation: 12/19/2020
Name: Irwin Guides
Subject: More action
Aspect: West
Elevation: N/BTL
Avalanches:
Worked primarily in the West today near and BTL. Paths still running full track with a whiff of a trigger. Ski pressure is more effective than explosives. Many rocks and logs. Full junk show
Weather: Wind up high. Solar aspects grew moist.
Photos:
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Zone: Northwest Mountains
Location: Near Lake Irwin
Date of Observation: 12/18/2020
Name: Zach Guy
Subject: This snowpack just sucks
Aspect: North East, East, South East, South, West
Elevation: N/BTL
Avalanches:
We remotely triggered a 2.5 foot thick persistent slab on a west aspect near treeline, small in size because it was on small terrain feature. Classic persistent slab behavior: skinned over the convexity expecting to trigger something, but then it went remotely after I was 30 feet away from the slope. We also noted a number of fresh natural slab avalanches below treeline closer to town (small in size), along with a dozen or so similar slides near Lake Irwin that ran earlier in the week, mostly N to E aspects N/BTL.
Weather: Pulses of moderate to heavy snowfall through the day. Light ridgetop winds where we traveled. Mostly cloudy skies.
Snowpack: The snowpack is still angry. About 8″ of storm snow produced minor cracking and a lot of small sluffs. But the big problem continues to be the buried 12/10 layer, which consistently produced collapses and shooting cracks on most low angle slopes that we traveled on. The persistent slab structure is still mostly fist hard, 18″ below treeline, and almost guaranteed shooting cracks and soft collapses on anything facing east or north. Near treeline, the slabs are a bit stiffer (up to 4F), 2′ to 3′ thick. The basal facets are capped by a stiffer wind crust so the collapsing isn’t quite as common, but booms and radiates further when it does.
We were targeting some forecaster uncertainty on how reactive SE aspects NTL are. Pits on suspect SE slopes showed the crust is thick, lacking a collapsible weak layer. Lower angle SE aspects still produced collapses because the crust is thinner. The few representative steep test slopes that we crossed didn’t produce any collapses, which was in contrast to a noisy snowpack on more easterly aspects.
RIP Jeff. I’ll miss your smile at the trailhead.
Photos:
