Anthracites avalanche activity

CB Avalanche Center 2019-20 Observations

Location: Kebler Pass Area
Date of Observation: 11/26/2019
Subject: Anthracites avalanche activity
Aspect: North
Elevation: 10,800

Avalanches: Unintentional skier triggered R1-D1 avalanche. First skier ski cut the slope and succeeded in triggering the top few inches – new storm snow – which ran with little energy 30 feet or so. Second skier descended where the first skier had ski cut, and in his second turn the slope triggered at the basal weak layer, fracturing several feet uphill of him. He was able to easily exit to the right as the 8 inches or so slid around him. It may have had just enough energy to take a skier off their feet and into obstacles below. This secondary slide ran 50 feet or so.

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Slate River Observations

CB Avalanche Center 2019-20 Observations

Location: Paradise Divide Area
Date of Observation: 11/26/2019
Name: Ian Havlick

Subject: Slate River Observations
Aspect: North East, East, South East, South, South West, West
Elevation: BTL

Avalanches:

some evidence of old dry loose avalanches with debris up to 6ft deep in the gully bottom of the upper slate drainage. Poor visibility limited observations within new snow and wind.

Weather: Cold with temperatures in the teens and dropping throughout our midday outing. NW winds were blustery and generally light BTL, but moderate gusts occasionally dropped windchills and visibilities. Snow intensified the farther from CB we traveled, with solid S2 midday and continuing when we departed. Accumulations from this round of snow was generally 2-4″ but closer to 6″ the farthest from town we traveled.

Snowpack: 3-6″ new, low-density cold smoke resting on November 20-22nd snowfall, and then in shady, northerly aspects BTL was the residual, rotten, faceted Halloween snowfall. Some shooting cracks in these rotten areas with deepest snowpacks and most windblown snow, failing in the newest storm snow (4-8″ deep). Harmless in terrain we traveled but likely deeper and more consequential at higher elevations.

Photos:

Mighty thin out there…
Mighty thin out there…
shooting cracks 8″ deep in freshly windloaded terrain steeper than 35 degrees.
Shallow windslab triggered in new snow on steep test slope convexity.  NE facing, Below Treeline.

Anthracites

CB Avalanche Center 2019-20 Observations

Location: Kebler Pass Area
Date of Observation: 11/25/2019
Name: Zach Kinler

Subject: Anthracites
Aspect: North, North East, East, South East, South, North West
Elevation: 10,000-11,500

Weather: OVC with intermittent S-1 beginning around 12:00, light SW wind, temps in the mid 20s steady

Snowpack: HS on N-E: 45-70 cm, S-SE 15-30cm. 30-40 cm of October snow exists from N-E and wind sheltered NW features at this elevation. The weakest snow was on sheltered northerly slopes where a razor thin crust sits on top of well developed 3 mm facets and multiple collapses were triggered on small terrain features. Large surface hoar up to 10 mm was observed on these same slopes. As you travel toward East, the crust grew to 4 cm with slightly larger facets underneath.

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Field Report 11/24/19

CB Avalanche Center 2019-20 Observations

Location: Paradise Divide Area
Date of Observation: 11/24/2019
Name: Sam Roberts

Subject: Field Report 11/24/19
Aspect: North East, East
Elevation: 12068

Avalanches: None

Weather: Clear skies with no wind, temperature floating around 1-2 degrees C.

Snowpack: We dug a pit within a wind loaded bowl on Mount Baldy’s South side on an E-NE aspect above tree line at 12,068′. The entire bowl we were in was extremely cross loaded and wind affected. Snow was 65cm total in depth with 3 distinct layers. The large basal layer was the late October snow storm and has developed into 35cm of fist hard 1-2mm facets topped by a 1-2mm crust that has formed a very slippery bed surface. We then found 10cm of 4 finger hard rounded grains without a definitive cap to it. The top 20cm of the snow pack was a layer of fist hard new snow. This top layer hard been wind affected and was a relatively cohesive slab. We performed both a column test and an extended column test on the snow and the results were not promising. The CT resulted in CTE with failure occurring at the crust that is capping the basal facet layer. The ECT resulted in ECTN 6 SC Q1 with the overlying new snow sliding very easily on the late October crust.

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Remote triggered slide BTL

CB Avalanche Center 2019-20 Observations

Location: Kebler Pass Area
Date of Observation: 11/24/2019

Subject: Remote triggered slide BTL
Aspect: North, North East
Elevation: 10600

Avalanches: One small D .5 natural on a N slope that looked to have filled in a little. Our party remote triggered another small slide on a NNE slope from below while skiing out. Two pockets pulled out across a rib with each pocket having a crown ~6-8m across and approximately 45cm tall. A deeper pack would have let a much more dangerous slide loose but today’s shallow pack would have only buried someone to their waist if they had been on that slope.

Weather: Bluebird. Some wind transport up high.

Snowpack: S-W sunny slopes moistened up throughout the day. Found the persistent weak layer on N-E slopes throughout the day. Several medium sized collapses on the skin track on the way up. S-W slopes had 30 cm snowpack. N-E varied from ~45cm to 100cm on wind-loaded features. 2mm surface hoar on most slopes BTL that didn’t disappear throughout the day unless exposed to direct sun.

 

Couple Old Natural Avalanches And Some Good Turns

CB Avalanche Center 2019-20 Observations

Location: Paradise Divide Area
Date of Observation: 11/23/2019
Name: Evan Ross

Subject: Couple Old Natural Avalanches And Some Good Turns
Aspect: North, South, West
Elevation: 11,000-12,300ft

Avalanches: A few persistent slabs ran naturally on NE aspects during the 11/22 storm. One of these was large in size and could have buried a person. The others were smaller but dragged through plenty of rocks and trees.

Schuylkill Ridge, NE aspect at about 11,350ft. SS-N-R1-D2-O, SS-N-R1-D1.5-O
The NE facing Shield at 12,000ft on Scarps Ridge may also have had a slab avalanche or at least just some sluffing but I didn’t get a good view.

Weather: Beautiful sunny and clear day. The nearby Cinnamon Weather Station at 12,293 reordered North winds in the 5 to 10mph range. and a high temperature of 25F at that elevation.

Snowpack: The last round of northwest to north winds on 11/22 had previously transported much of the recent new snow on wind-exposed terrain features at both above and near treeline elevations. More protected terrain features had some wind stiffened snow on the surface or no wind effect at all.

The 11/22 storm dropped about 5-6″ of low-density new snow. The couple inches of new snow from the 11/21 storm felt like it had some moisture pulled out of it and had lost some of its soft slab feel compared to my observation on 11/21. No signs of instability were observed despite the very weak 11/20 interface we were traveling on. Maybe this was due to some of the moisture being pulled out of the 11/21 storm and a general soft over soft snowpack structure, or maybe the unstable pocket just wasn’t encountered. The public was also out in force getting some good turns on Northerly and Westerly facing terrain at near and above treeline elevations. From social media pictures, it doesn’t currently appear that anyone found any significant signs to current instability.

The new snow that has accumulated on southerly facing slopes was thick and moist by Saturday afternoon. This snow will probably melt on some slopes by Monday or form crusts down the ground or the 11/20 melt-freeze crust.

While we may not have seen signs of instability today, the snowpack is ripe for unstable conditions once we start seeing a load applied or slabs forming. As noted in previous observations, the 11/20 interface is particularly weak where it was protected from past wind events and the sun. This weak interface can be found on shaded terrain features and/or NW to N to E aspects. Northerly to Easterly aspects above 11,300ft are probably the best bullseye.

Photos:

Shooting Cracks, Mt Baldy.

CB Avalanche Center 2019-20 Observations

Location: Paradise Divide Area
Date of Observation: 11/22/2019
Name: Evan Ross

Subject: Shooting Crack, Mt Baldy.
Aspect: North, South, West
Elevation: 11,000-12,000

Weather: Nearby Cinnamon Weather station at 12,293ft recorded westerly winds averaging 25 to 15mph from 6am until noon. In the afternoon clouds were hanging on the peaks and there was absolutely no wind. A nice blue hole in the clouds rolled through for about an hour followed by overcast sky for the rest of the afternoon.
Snowpack: About 3″ of snow had accumulated from the recent storms on Wednesday and Thursday morning. The westerly wind was strong enough to drift that little bit of new snow about and create some wind texture on upper elevation exposed terrain.

The old October snow is variable in both its location and current type. In many areas that snow has been melted away or very wind effected with tightly packed small grains. Both of these setups posed the leased concerns. That old October Snow is concerning in areas more protected from the sun and from the wind events in late October/early November. In those areas, the old snowpack is faceted and weak, especially the NSF development in the upper 10-15cm of the old snow. This weak snow will take little load to become an avalanche problem in the future. South to Southwest to West at ~11,600ft. The October Snow is either completely melted away or a 5-15cm melt-freeze crust on the ground. Of particular note, the portions of these slopes that were shaded by tree stands held pockets of a weak faceted old snowpack.

North to Northwest between 11,600-12,000ft. HS averaged about 50-60cm or around 2 feet. Some areas were disturbed by previous winds and the stacks of old wind slabs and wind-packed grains were less concerning. Otherwise, the snowpack in this area could be generalized as faceted and weak. The 11/20 interface was the most concerning with well developed 1-2mm faceted grains that were already becoming sensitive with the very shallow and soft slab forming over them. A .5cm melt-freeze crust was fairly widespread in this area and may help aid propagation in the future. Shooting cracks were observed on a portion of a 30-33 degree slope at 11,900ft.

Photos:

Kebler Pass Pre-Storm Observations

CB Avalanche Center 2019-20 Observations

Location: Kebler Pass Area
Date of Observation: 11/19/2019
Name: Ian Havlick

Subject: Kebler Pass Pre-Storm Observations
Aspect: East, South East, South, South West, West
Elevation: 10,000-12,000

Avalanches:

none.

Weather: Clear skies becoming scattered to overcast mid-afternoon. Light winds below treeline, gusts to 35mph above treeline at 12,000 Scarp Ridge station. Temperatures midday were 33º at 12,000ft. Mild and almost T-shirt in sun.
Snowpack: bare ground on E-S-SW aspects with residual halloween snow hanging on shaded westerlies and northern half of compass. west facing snow was generally baked faceted rounds, with cohesionless facets in the shade and northerlly aspects. Snow depths 10-20cm.

Photos:

Snow coverage from October storms

CB Avalanche Center 2019-20 Observations

Location: Kebler Pass Area
Date of Observation: 11/18/2019
Name: Eric Murrow

Subject: Snow coverage from October storms
Aspect: North, North East, East, South East, South, South West, West, North West

Snowpack: Snowfall from October has been melted to dirt, or at best, patchy coverage for slopes on the southern half of the compass, while the northern half of the compass has held on to a thin, continuous layer. Snow that has persisted on sunny slopes has developed into a patchwork of crusts. The snowpack on northerly facing slopes has been faceting, weakening, and will provide a poor foundation for the incoming storms. I would anticipate some avalanche activity on shaded slopes if the forecasted storms produce over the next week. Below are photos from around the range; take a gander and find the photos of terrain you play in and make note of what the incoming storms will be falling on.  Gallery generally shows terrain from west to east across the forecast area.

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