Avalanches at Kebler Pass & Irwin

CB Avalanche Center2015-16 Observations, Snow Profiles

Location: Kebler Pass Area
Date of Observation: 01/17/2016
Name: Zach Guy
Subject: Avalanches at Kebler Pass & Irwin
Aspect: West, Southeast
Elevation: N/BTL

Avalanches: On a SE aspect near treeline, a 2lb handshot triggered a large soft slab, 65 cm deep and ~200 ft wide, that failed in a thin facet layer below the Jan 14th meltfreeze crust.  SS-AE-R2-D2-O.  See profile. Widespread storm slab instability with more than a dozen natural and skier/snow cat triggered soft slabs (Fist hard, 3-10” deep, failing on precip particles) along various aspects of Kebler Pass Road and on Irwin terrain. Minor propagation decreased through the day (max 60 feet wide, avg 20-30 ft), and easily managed, ran more like loose snow avalanches. Harmless in size. SS-ASc/AK/N-R1-D1-S
Weather: Calm to light winds, with moderate gusts from S to W. S-1 to S2 snowfall. Overcast skies.
Snowpack: 18” of very low density snow with minimal wind affect fell last night. On west aspects N/BTL, the storm interface (Jan 14th near-surface facet layer) is ~30” deep in relatively windsheltered terrain; deeper or shallower in wind affected terrain. One pit in an untrafficked area showed the layer is unreactive; size/hardness change was indistinct, with small grained rounding facets at the interface. See profile 1. On SE aspects near treeline, the slab was 26″ deep, but denser from wind effects, over reactive crust/facet/crust sandwiches. See profile 2 and avalanche ob.

Upper snowpack on a west aspect near treeline
1/17. Crown Profle SS-AE-R2-D2-O

1/17. Crown Profle SS-AE-R2-D2-O

1/17. Explosive triggered slab avalanche at Irwin. SE aspect NTL.

1/17. Explosive triggered slab avalanche at Irwin. SE aspect NTL.

1/17. Explosive triggered slab avalanche at Irwin. SE aspect NTL.

1/17. Explosive triggered slab avalanche at Irwin. SE aspect NTL.

1/17. Explosive triggered slab avalanche at Irwin. SE aspect NTL.

1/17. Explosive triggered slab avalanche at Irwin. SE aspect NTL.

Snodgrass

CB Avalanche Center2015-16 Observations

Location: Crested Butte Area
Date of Observation: 01/16/2016
Name: Irwin Guides
Subject:
Aspect: North, North East
Elevation: 9600-10800

Avalanches:
Weather: High around 15F, small period of S-1towards the end of the afternoon, Light winds out of NE. Scattered sky most of the day.
Snowpack: HS ranges from 85-100 cm. 10 cm of new snow from the last storm. No signs of instability, 26cm boot pen/15cm ski pen, CT20 on the ground facet layer. 3-4 cm facets on the ground. There is aspect of a 4f soft slab in this area. I skied the north ski of snodgrass yesterday and the snow did not have any aspect of a slab.

East River/White Mountain

CB Avalanche Center2015-16 Observations

Location: Crested Butte Area
Date of Observation: 01/16/2016
Name: Ian Havlick
Subject: East River/White Mountain
Aspect: East, South East, South, South West, West
Elevation: 8800-11300

Avalanches: no new avalanches observed
Weather: Scattered to broken skies, with some pleasant sun in the morning. Cold and steady N-NW winds all day, no new snow. no sensible solar radiation.
Snowpack: 3″ new, semi-dense wind effected snow overnight, blown around into various thicknesses of wind crust/slab 3-24″ deep in some areas. All new snow fell on large facets, ski pen was still 20cm, boot pen to ground. Did feel two medium sized whoomphs while travelling on the thickest fresh wind drifts of the day near a small ridgeline. Steady and significant windloading E-SE-S aspects above treeline.

Copper Creek near Gothic

CB Avalanche Center2015-16 Observations

Location: Crested Butte Area
Date of Observation: 01/16/2016
Name: Evan Ross
Subject: Copper Creek Level 1 Obs
Aspect: North, West
Elevation: 9000-10500

Avalanches:
Weather:
Snowpack: Short tour up copper creek to west facing slide path around 10400f btl. No Avalanche problems on slopes less then 35 degrees. Could have found small sluffs on steeper slopes. Found 1, 2-8″ wind slab over nsf with shooting cracks. Slab was only about 15 feet long and 3 feet wide. Looked like a few other very small wind slabs in the terrain. Cold temps and gusty westerly winds blowing snow at times.

Gothic Area

CB Avalanche Center2015-16 Observations

Location: Crested Butte Area
Date of Observation: 01/15/2016
Name: Donny
Subject: Gothic Area
Aspect: East
Elevation: 9,500′ to 11,200′

Avalanches:
Weather: Light snow until about 3PM, HST 4″ to 6″; Moderate north wind in valley and ridges; temps in the teens all day.
Snowpack: No signs of instabilities all day. New snow of 4″ to 6″ is still fist hard, and only slightly slabbing up in a few places. Average HS between 60cm and 80cm. SkiPen of 30cm to 40cm all day. BootPen basically full depth.

Scarp Ridge

CB Avalanche Center2015-16 Observations

Location: Kebler Pass Area
Date of Observation: 01/16/2016
Name: Zach Guy
Subject: Scarp Ridge
Aspect: North East
Elevation: 12,000 ft

Avalanches: Most terrain obscured by poor vis, but saw one natural wind slab on a wind loaded NE aspect above treeline. ~2ft crown, mostly filled in already, failed earlier in this storm. SS-N-R1-D2-U. Very small wind slab failed again in same path today.
Weather: Moderate to strong SW winds with moderate snow transport. S-1. Broken to overcast skies
Snowpack: 15″ of storm snow, with drifts up to several feet thick.

1/16. Larger crown getting filled in, smaller crown above it. NE aspect above treeline.

1/16. Larger crown getting filled in, smaller crown above it. NE aspect above treeline.

Schuylkill Ridge

CB Avalanche Center2015-16 Observations

Location: Paradise Divide Area
Date of Observation: 01/15/2016
Name: Zach Guy and Brian Lazar
Subject: Schuylkill Ridge
Aspect: North East, East
Elevation: 9,200-11,300

Avalanches: On a NE aspect NTL, we kicked a small cornice that triggered a loose snow avalanche gouging into old facet layers and ran 1,100 vertical feet. Given the gulley feature it ran through, the slide could have injured or buried someone. L-AC-R1-D1.5-O. No other avalanche activity observed.
Weather: Overcast decreased to broken skies. S-1 snowfall in the morning. Moderate SW ridgetop winds, with light snow transport. Plumes from NW winds observed on Mt. Emmons as we left the trailhead in the afternoon.
Snowpack: 5 cm of storm snow over a widespread near surface facet layer. Minimal wind affect below leeward ridgelines, with drifts 10-15 cm. New snow was noticeably more wind affected mid to lower on the slope from cross-loading down valley winds. Observed drifts up 25cm thick with cracking up to 10 feet on steep rollovers, but no avalanches. HS in old refilling avalanche paths was 50-80cm. More a like 120-150 in areas that didn’t avalanches, but there weren’t many paths in this area that didn’t run. Most of the terrain avalanched during Xmas cycle leaving only weak snow 50-80 cm and almost entirely facets, with 5cm of new snow on top. Just below ridgelines the drifts the suspected wind slabs avalanche problem was not there. Suspect there are stiffer wind-drifted slabs near Kebler that got more snow to move, and also up ATL where winds were stronger.

obs_38542_11251-r

NE aspect near treeline on Schuykill Ridge. The red oval indicates areas we thought we would find developing wind-drifted slabs, but there was little wind affect up near ridgeline.   Surprisingly more wind affect closer to valley floor from down valley crossloading.

obs_38542_11254-r

Looking into the narrow gulley where a Loose Dry avalanche plunnged 1200 feet. Schuylkill Ridge 1.15.16

 

Large natural on west side of Ruby Range

CB Avalanche Center2015-16 Observations

Location: Kebler Pass Area
Date of Observation: 01/14/2016
Name: Zach Guy
Subject: Large natural on west side of Ruby Range
Aspect: East, South West, West
Elevation: 10,000-11,800 ft

Avalanches: We came across a surprisingly fresh D2.5 debris pile on west side of Ruby Range. Start zone obscured by clouds. Appears to have failed in the past week because the 10″ that fell on 1/7 was not on top of the debris. Could see some flanks mid track that looked about 2 feet deep and gouged to ground. Start zone was either SW or W aspect above treeline. Speculating that it was a persistent slab triggered by either a small wind slab a few days ago or a small wet loose avalanche yesterday? Noteworthy because it is the only persistent slab we’ve seen fail in the past few weeks, and one of the only large naturals from that aspect observed during Xmess Cycle. We observed 4 fresh wet loose avalanches on S/SW aspects below treeline.
Weather: Light to moderate snow (S1-S2). Moderate WSW winds with moderate snow transport at ridgeline. Overcast. Cold temps.
Snowpack: 2″ of new snow by 2 p.m.
N/ATL East aspects: Snow depths ranged from 180 to 250 cm. No wind effect in recent snow (ski pen was shin deep), except some slightly stiffer snow at ridgeline. No signs of instability on steep terrain.
N/ATL West aspects: Variable snow depth and structure; difficult to generalize. Upper start zones were mostly shallow and faceted (<50cm), with some pockets up to 180 cm deep with variable hardness structures. No signs of instability.

Small wet loose below treeline
Debris looking up towards obscured start zone
Looking down at debris.  Broken tree limbs and several meters deep.

Crested Butte Area

CB Avalanche Center2015-16 Observations

Location: Crested Butte Area
Date of Observation: 01/13/2016
Name: Donny
Subject: Crested Butte Area
Aspect: West, North West
Elevation: 9000’ to 11,800′

Avalanches:
Weather: High thin clouds, light north wind above 11,500’ and Africa Hot – 34ºF at 11,000’ at 1:00.
Snowpack: No signs of instabilities. No slab present on any part of tour – full depth facets with HS between 50cm and 80cm.

Emmons Structure

CB Avalanche Center2015-16 Observations

Location: Crested Butte Area
Date of Observation: 01/13/2016
Name: Evan Ross
Subject: Emmons Structure
Aspect: North, North East, South East
Elevation: 9,000 to 12,000

Avalanches:
Weather: Mostly clear with high thin clouds building by 11am. Calm wind. Very cold inversion already set up again while crossing the slate river at 3:30pm.
Snowpack: Near surface facets or weak surface snow is all over the place. Recent winds have buffed or stripped snow from north to west facing slopes near the summit ridge lines of Mt. Emmons.

Snowpack structure on a protected SE aspect, 32 degree slope at 11,200 was just crusts and facets for about 80cm without any slab or avalanche problem.

Snowpack structure in Redwell just after dropping into the bowl and where the slope becomes uniform below cliffs, NE aspect 35 degree slope at about 12,100, was a perfect and scary feeling persistent slab set up. HS 130, with an estimated 1f to 4F+ slab about 60cm thick over about 60cm of very weak feeling structure below. Still, many tracks on slope with no result. If that same structure exists on the steeper slopes in the area where there are no tracks, then they seem like they could still produce a persistent slab avalanche. Only had a chance to sample this one small area in this large terrain feature.

Snowpack structure in the north facing runout of redwell below 10,600ft was a simple weak, faceted snowpack with little layering remaining.