Natural slab avalanches on Baldy and Gothic

Location: Paradise Divide Area
Date of Observation: 11/11/2015
Name: Zach Guy
Subject Natural Slab Avalanches on Baldy and Gothic
Aspect: North, North East, South East
Elevation: 10,300-12,200 ft

Avalanches: Several natural avalanches observed that failed overnight during the storm. See photos and video.

  • 2 large natural slab avalanches on a N to NE bowl on Mt. Baldy, above treeline. They appeared to be sympathetic, with their combined start zones spanning 700 feet, and debris ran 1,800 vertical feet, almost reaching the creek at the bottom. Crowns estimated 2 – 3 feet deep. Failed on 1mm facet layer on the ground. SS-N-R2-D2-O/G
  • 1 natural slab avalanche on the north face of Gothic Peak above treeline, failing near the ground but smaller in width and length than the Baldy slides. SS-N-R1-D1-O/G
  • 2 natural wind slab avalanches on a SE shoulder of Baldy near treeline, estimated 1-2 feet deep and 75 feet wide, likely failed on storm interface. SS-N-R1-D1-I

Weather: Scattered clouds. Cold temps. No precip. Moderate northwest ridgetop winds with strong gusts; moderate snow transport.
Snowpack: The persistent slab structure existed above 10,700 feet on north and northeast aspects. Slab depths ranged from 40 cm up to 90 cm, above ~5-10 cm of 1mm facets. At 11,600 ft, the slab was 4F at the bottom up to F at the top. 30 cm of storm snow. The storm interface was indistinct in pits, with no surface hoar observed in several locations and no results in extended column tests. Clean shovel shears though.

North aspect above treeline.
Debris ran over this rollover and almost reached valley bottom.
Two faintly visible slab avalanches on a SE aspect near treeline that ran mid-storm.

Snodgrass

Location: Crested Butte Area
Date of Observation: 11/11/2015
Name: Andrew Breibart
Subject Snodgrass
Elevation: 9300 to 10,800

 
Weather: Overcast skies. S-1 transitioning to no snowfall. Winds were light with moderate gusts, transitiong to just light winds. Winds were strong enough to fill in skin tracks between road and first hill climb.
Snowpack: About 3 to 4 inches of new snow

Elkton

Location: Paradise Divide Area
Date of Observation: 11/10/2015
Name: Zach Guy and Ian Havlick
Subject Elkton
Aspect: East, South East, South
Elevation: 11,000 ft.

Avalanches: None.
Weather: Increasing clouds, moderate south winds, temps near 30*F. Elkton weather station (aka Dan K station) is now fixed! We are putting a bounty out for the live capture of the marmot that keeps chewing through our electronics every summer.
Snowpack: Snow depth roughly 4-6″ deep, moist snow with melt-freeze crusts at the surface. The surface hoar got cooked on steep south and southeast aspects, but lingering on east aspects and lower angle slopes. Steep aspects have <1mm near surface facets growing above the crusts on these slopes.

Surface obs and snow structure on Purple

Location: Paradise Divide Area
Date of Observation: 11/09/2015
Name: Zach Guy
Subject Surface obs and snow structure on Purple
Aspect: North East, East, South East
Elevation: 10,000 – 11,500 ft

Weather: Few clouds, calm wind.
Snowpack: Continuous snow coverage now on all aspects/elevations except for some below treeline southerly slopes. Snow surface was re-freezing crusts on every slope SE, S, and SW. Widespread surface hoar layer at all elevations on shady aspects, ranging from 2-3mm at lower elevations to 1mm at higher elevations. Some minor faceting below the surface hoar as well. Last week’s snow is now denser and supportive, ranging from 20cm or less at 10,000 feet and up to 60 cm at 11,500 ft. Encountered old facet layer below last week’s snow around 11,000 feet and higher on northerly aspects. Snow profile here showed 45 cm of slab over 10 cm of 1mm facets. Propagating results in stability tests and got a moderate collapse about 10 feet from my pit as I was leaving. See attached profile. Slabs become more variable in depth and density at higher elevations due to wind effects. Observed some minor cracking above 11,000 feet as well.

Surface Hoar, Near Surface Facets, And Crusts

Location: Paradise Divide Area
Date of Observation: 11/09/2015
Name: Nick Schley
Subject Surface Hoar, Near Surface Facets, And Crusts
Elevation: 9,000-12,000ft

Avalanches: One R2, D1, Avalanche on Augusta’s NE arm, Crown height ~30cm appeared to release in a mid storm layer, did not inspect crown interface. Probably 3-5 days old.
Weather: Cool, Clear, Gorgeous before 11:00 am.
Snowpack: SE-S-SW slopes below 11,500 all held thick pencil hard crusts from this weekends sun. Those crusts were topped by small near surface facets and 2-3mm tall surface hoar crystals. HS around 60cm primarily sitting on ground not previous Oct snow.
NE-N Persistent slabs lurk. Probing revealed HS to be between 90cm and 130cm above 10,500. Two pits yesterday revealed right side up pack until a quick shift from 1F hard storm slab to 10cm of fist hard basal facets. Did a fair bit of traveling on these aspects today, did not experience any settlements. Small near surface facets developing here. Ski pen 10-15cm.

Avalanche on north face of Mt. Baldy

Location: Paradise Divide Area
Date of Observation: 11/07/2015
Name: Randy Felix
Subject Avalanche on north face of Mt. Baldy
Aspect: North

Avalanches: North face of baldy. Approx 100-200 feet from summit. 2.5ft crown. Approx 100 ft. Wide ran for several hundred feet. Being conservative. Looks to have slid on an old storm layer possibly a wind slab near the ground. I did not inspect the bed surface. Avalanche was soft slab and fairly slow moving.
Weather: Clear calm and sunny.
Snowpack: Powder. Approx 20 inches of new snow or whatever the exact storm totals were for Washington Gulch area.

All Quiet in Baxter Basin

Location: Paradise Divide Area
Date of Observation: 11/08/2015
Name: Dustin
Subject All Quiet in Baxter Basin
Aspect: North, North East, East, South East, South, South West
Elevation: 9,200-11,700

Avalanches: Looked as though some slopes slide mid-storm on N-NE-E aspects above treeline.
Weather: Cold and clear in the morning with temps rising throughout the day. Calm winds throughout the day.
Snowpack: Still pretty shallow below 10,000 feet. Found thin crusts from yesterday’s sun on southerly aspects with snowpack on solar aspects above treeline around 40-50cm almost entirely comprised of recent storm snow. On North-NE facing aspects above treeline we found 95 cm of right-side-up snow with the bottom 10 cm weaker faceted crystals from prior snows. On two ECTs we got ECTN and ECTP (23) Q3 fracture at interface with faceted layer.

Mount Bellview

Location: Paradise Divide Area
Date of Observation: 11/08/2015
Name: Erin Kearns
Subject Mount Bellview 11/8/15
Aspect: North, East, South East, South, South West, West
Elevation: 9000′-12,400′

Avalanches: Small loose dry observed on NE aspect of Mt. Baldy
Weather: Mid-late teens early in the morning with temperatures rising steadily throughout the day and peaking in the mid 30’s around 12:30pm. Sunny, clear skies, calm wind.
Snowpack: -Saw a little bit of everything today on Mount Bellview.
-The most recent storm snow was settling, measuring 15-20cm deep in most areas. The exception was on the W-SW facing aspects, where it was significantly shallower (5-10cm)
-W-SW aspects appeared to have frozen into a crust the previous night, slow to soften throughout the day.
-Windloading occurring on S-SE-E aspects. Cornices beginning to form on all of these aspects. Wind slab forming at higher elevations mainly on the SE-E about 25cm deep.
-N Aspect: 3cm facets at the ground layer, buried by 2 interfaces (approx: 15cm each), each forming significant slabs. Lower slab was weaker and less cohesive than the upper.
-Heavy springlike conditions in the basin 12:30-1:30pm.

Cascade/daisy

Location: Paradise Divide Area
Date of Observation: 11/07/2015
Name: EM
Subject Cascade/daisy
Aspect: North East, East, South East, South, South West
Elevation: 9000 – 11400

Avalanches: No slab avalanche activity. Many steep cliff areas shed dry point releases during storm.
Weather: clear skies with very occasional light winds. Temp was 8 f at 9am at TH. temp in the sun at 11400 was 35 f at noon.
Snowpack: On sunny aspects the snowpack consisted mostly of new snow with only a few patches of old crust underneath higher up. Shaded aspects had 1mm facets underneath new snow. One location on a ENE 35* roll at 11200 had 5cm basal crust , 35cm 1mm facets, 45 cm new snow. Tests showed both interfaces had not bonded well. Snowpack overall showed signs of settlement which made riding conditions more supportable. Noticed only small amount of wind effect snow up high on NE flanks of Richmond.

Skier Triggered Slab Avalanche on Baldy

Location: Paradise Divide
Date of Observation: 11/07/2015
Subject Skier Triggered Slab Avalanche on Baldy
Aspect: North
Elevation: Above Treeline


Avalanches: On a north facing bowl on Mt Baldy. SS-AS-R2-D2-O

Photo credit Austin Gibney