Like skinning in a sandbox

CBAC 2020-21 Observations

Zone: Northwest Mountains

Location: Hancock

Date of Observation: 11/30/2020

Name: Zach Guy

 

Subject: Like skinning in a sandbox

Aspect: North East, East, South West

Elevation: 9,600 – 12,400′

Avalanches:

None today.

Weather: Clear skies, mild temps, moderate westerly winds

Snowpack: We found good stability on steep terrain and noted plenty of weak layers on the snow surface for future problems. Several pits on NE aspects targeting persistent slab concerns were unreactive. In previously wind loaded areas(HS~90 cm), the basal facets show signs of being stronger, harder, and smaller grained now, and were also discontinous due to talus on the ground. In previously wind-scoured or shallow areas areas, the snowpack is quite weak (Fist hard, 1mm facets) but no slab. Snow surfaces consist of widespread .5mm near surface facets on northerly aspects, occasionally capped by a thin wind crust that produced clean shears and cracking. On southerly aspects, the surface is melt-freeze crusts of varying hardness with small grained facets above and/or below. It is hard to find a slope where there isn’t a PWL on the surface, except for the ones that have melted out to dirt. No signs of instability today on slopes up to 40 degrees.

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Groundhog’s day can be fun

CBAC 2020-21 Observations

Zone: Northwest Mountains

Location: Upper Slate

Date of Observation: 11/29/2020

Name: Zach Guy

 

Subject: Groundhog’s day can be fun

Aspect: North, North East

Elevation: 9700-12,200′

Avalanches:

No recent avalanches. Spotted a few more small wind slabs from early last week.

Weather: Awesome.

Snowpack: Continuing the hunt for persistent slab feedback and not finding it. Went to a high, northerly bowl that we documented in early November as a potential problem slope with continuous weak layer coverage across the whole bowl. The 11/14 northwest wind event had clearly scoured back most of the slab, evidenced by reverse cornicing on the ridge, some veg poking out mid-bowl, and pole probing. A representative pit photo is attached, showing a shallow snowpack without the structure for a persistent slab. There were a few small lobes of potentially crossloaded slabs in the bowl that we easily avoided. We rode in steep terrain with no signs of instability.
In general, the snowpack here is weathering the decaying process much better than what I observed recently at Coney’s and Snodgrass: previous wind events and/or a deeper warmer snowpack is maintaining a supportive midpack so far. Near surface faceting is still occurring at all elevations. No surface hoar observed here.

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NE powder SW sun crusts

CB Avalanche Center 2020-21 Observations

Zone: Northwest Mountains

Location: Poverty Gulch

Date of Observation: 11/28/2020

Name: Travis Colbert

 

Subject: NE powder SW sun crusts

Aspect: North East, South West

Elevation: 9,200-11,600

Avalanches:

Very slow moving sloughs (top 20cm) on 36-38 shaded slopes. Very slow moving shallow slough/slab (10cm sun crust) on 32-34 degree sunny slope.

 

Weather: Blue skies & very little wind. Single digits in the morning, warming to the lower 20s by afternoon.

Snowpack: HS 90-95cm on shaded NE slopes; upper 20cm unconsolidated new snow sitting on a soft crust. HS much lower (did not measure, but maybe 20cm) on sunny SW slopes; but compacted and supportable with 8-10cm soft sun on the surface.

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Poverty Gulch

CBAC 2020-21 Observations

Zone: Northwest Mountains
Location: Poverty Gulch
Date of Observation: 11/28/2020
Name: Evan Ross

Subject: Poverty Gulch
Aspect: North East, East
Elevation: 9,500-12,000

Weather: Another beautiful weather day. Light winds at ridgeline and high temps felt like they reached into the upper 20’s to near freezing.

Snowpack: It’s sad to see the cold clear nights faceting away the upper snowpack. The mid-pack still had good support for now, and the combination of the weak upper snowpack and stronger mid-pack is keeping the skiing good. Unfortunately we are watching or snowpack go its typical Continental direction.

Focusing on the now, and not what we’re going to be dealing with later. Normal caution feels spot on. Or, good group travel techniques, while keeping an open eye out for something isolated that doesn’t look or feel right. It’s getting hard to call a specific or particular increased hazard to manage, but rather the standard general awareness and normal caution seem most appropriate.

There were several old sluffs in the terrain, and fresh skier triggered sluffs in steep terrain. These were to small to pose much of a hazard, but highlight the weakening snowpack all the way up to upper elevations.

Upper Slate

CBAC 2020-21 Observations

Zone: Northwest Mountains
Location: Purple Ridge
Date of Observation: 11/26/2020
Name: Evan Ross

Subject: Upper Slate
Aspect: East
Elevation: 12,000-9,600

Weather: Clouds decreased to partly cloudy during the mid-day, then started increasing to mostly cloudy again in the afternoon. Mild temps. Clam winds down low. Moderate wind at ridgeline with periods of snow saltation close to the ground. No plumes off the high peaks. Up to an inch of new snow today baby! Keeping it soft, better than nothing.

Snowpack: Traveled in this same area a couple of days ago. Not much change. The old wind-drifts at ridgeline were hard and didn’t give any signs to instability. Today’s new snow had formed some soft few inch drifts right near ridgeline.

Backcountry riders continue to step out and ride more and more terrain features. With conditions going mostly quiet I suspect we will see few observations come in.

Bit of this bit of that

CBAC 2020-21 Observations

Zone: Northwest Mountains

Location: Poverty Gulch – around easterly side of Mineral Point

Date of Observation: 11/25/2020

Name: Eric Murrow Zach Kinler

Subject: Bit of this bit of that

Aspect: North East, East, South East, South

Elevation: 9,500 – 11,650

Avalanches:

Several small (D1) wind slabs observed on east and northeast above treeline slopes. One below ridge top, others mid feature on small inset portions of the feature.

Weather: Cold temps at valley bottom gave way to warm, pleasant. conditions on sunny terrain features. Light winds near and below treeline; some blowing snow and loading above treeline on to southeasterly slopes.

Snowpack: Sunny slopes had several inches of moist snow resting on supportive crusts. The snow on warm features wetted to old crust and refroze to old surface once the sun left the terrain below treeline.

East facing slopes remain dry below and near treeline in this area. Evidence of some wind redistribution near treeline, but really no hazard from Wind Slabs in areas traveled. We were able to produce some minor cracking on the most suspect drifts, but nothing more.

Stomped around on several small drifts behind tree fences on northerly terrain and got one localized collapse on an obvious wind whale but it didn’t produce any cracks. Probing showed weak faceted snow at the ground, but outside the wind whale there just wasn’t much of a slab.

Photos:

Small sluffs and slabs at upper elevations from the past 48hr’s

CB Avalanche Center 2020-21 Observations

Zone: Northwest Mountains
Location: Upper Crystal Watershed
Date of Observation: 11/25/2020
Name: Evan Ross

Subject: Small sluffs and slabs at upper elevations from the past 48hr’s
Aspect: North, East
Elevation: 11,000-12,000

Avalanches: Maybe 20’ish small avalanches at upper elevations, mostly releasing from wind-loading, but a couple coming out of rock bands. A few from today, others were slightly older. Mostly sluffs, or maybe small cornice chucks coming down. Few small crowns. There could have been more crowns that were either too small to see, or had blown back over. These avalanches were observed on west,  north and east aspects, with easterly having the most activity.

Weather: Clear, mild temps. Moderate ridgetop winds with light transport. Mostly calm conditions at lower elevations.

Snowpack: North 11-12,000ft: Skied a couple different laps and a couple different skin tracks. HS was generally in the 60 to 80cm range. We traveled on new snow over old wind-board, to a general 70cm snowpack over a thin layer of dry facets, and through many transitions from the supportive slab into shallow a less supportive snowpack. All and all the snowpack was mostly quiet outside of a couple of small collapses. Those collapses didn’t seem to collapse big parts of the slope. The layer of facets at the ground is fairly thin and maybe there was too much ground roughness.

Easterly 11-12,000ft: Great riding conditions on east with the new snow over a supportive snowpack. Tilt a little SE and the snow-surface was becoming moist. We climbed into the start-zone of an easterly bowl right below a ridge. Sections of the bowl were stripped of the new snow by NW winds. Other sections had more of a cross-loading pattern. We moved through a few thick cross-loaded drifts on 35-degree slopes. Those drifts were thick and not giving us any feedback to instability.

All and all, we found good stability and some lovely turns.

Also noticed several ski tracks of folks skiing some large bowls on the northerly side of Baldy, and on both easterly and northeasterly bowls off Purple Ridge. Looked like some folks got some good turns.

 

Stubborn wind slabs

CBAC 2020-21 Observations

Zone: Northwest Mountains

Location: Augusta

Date of Observation: 11/25/2020

Name: Zach Guy

 

Subject: Stubborn wind slabs

Aspect: East, South East, South

Elevation: to 12,500′

Avalanches:

Two small natural windslabs on easterly aspects near and above treeline that likely ran Tuesday morning. A dozen or so small loose dry avalanches on steep northerly terrain in more sheltered basins, likely similar timing. All D1s.

Weather: Clear, mild temps. Moderate ridgetop winds with light transport, a brief period of moderate transport this afternoon.

Snowpack: About 4″ to 6″ of settled storm snow, generally on a stout melt-freeze crust on the sunnier aspects that we traveled on. The snow saw a fair amount of redistribution from northwest winds at near and above treeline elevations – drifts up to 18″ thick. Wind slabs were quite stubborn today; minimal feedback from stomping on test slopes. Got one crack after undercutting a steep, wind-loaded feature and then stomping on it from above (See photo). Skied terrain up to 38* with no instabilities.

Photos:

Sunpow

CB Avalanche Center 2020-21 Observations

Zone: Northwest Mountains

Location: upper end of Slate River Valley

Date of Observation: 11/25/2020

Name: Than Acuff

 

Subject: Sunpow

Aspect: North East

Elevation: BTL to ATL

Avalanches:

None observed, new snow stuffing from below rocks on north aspect above treeline.

 

Weather: Sunny and temps ranged from single digits (morning in valley floor) to 30’s (1 p.m. valley floor).

Snowpack: There were spots where the snowpack had 7 inches new new on top of 20 inches of denser snow and no crusts on a more north aspect in the open but below treeline. Then, 50 feet further it was 7 inches on top of 20 inches of unconsolidated snow. And then, off the ridge top was 8 inches of new snow sitting on a firm crust on NE aspects and deeper pack, 30 inches total give or take. And small pockets of wind load off the ridgetop.
I am super psyched on the early bird raffle and virtual Awareness Night on December 4.

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