Coney’s

CB Avalanche Center2016-17 Observations

Location: Crested Butte Area
Date of Observation: 02/09/2017
Name: Arden Feldman
Subject: Coney’s
Aspect: North East, East, South East, South, South West, West, North West
Elevation: 10,600

Avalanches: Many small natural wet loose avalanches on steep southerly aspects, even saw some on a northwest aspect below tree line running off some cliffs. No slab avalanches observed on Schuylkill Ridge or the surrounding mountains.
Weather: Warm temps and light winds. Clouds decreasing through the day with few clouds by the afternoon.
Snowpack: Snow surfaces on east aspects below tree line had a very thin crust in some places but were generally relatively dry in the afternoon. Snow surfaces on west aspects below tree line seemed to have received more warming and were wet down to a couple of cm’s, likely due to the decreasing clouds through the day. On a northeast aspect below tree line the 1/19 interface was 75 cm down and had an obvious large surface hoar layer. The top 25 cm’s of the slab were entirely graupel. An ECT did not produce any results in the first 30 taps, but after removing some of the slab below the shovel it fully propagated with one more hard tap.

Wet-Loose
Graupel

Avalanche off of Gothic

CB Avalanche Center2016-17 Observations

Location: Crested Butte Area
Date of Observation: 02/09/2017
Name: billy barr
Subject: Avalanche off of Gothic
Aspect:
Elevation:

Avalanches: The big slide off the peak area of Gothic ran, I believe between 1-3 p.m. today. Ran off old snow and no where did it run to ground, but had a decent amount of debris. A size 3 (I do not know new system) with a guess of a fracture 3-4 feet deep and ran about 2700 feet. Also some little sluffs up the valley.
Weather: a record high of 47F today.
Snowpack:

Gothic Townsite Snow Obs

CB Avalanche Center2016-17 Observations

Location: Crested Butte Area
Date of Observation: 02/08/2017
Name: billy barr
Subject: Gothic Townsite Snow Obs
Aspect:
Elevation: 9300

Avalanches:
Weather: Well, I was sort of close- overnight was 5″ and 0.70″ of water- which is probably the densest snowfall I have ever recorded (14% water- usually around 6% this time of year). The 24 hour total was not much better with 10.5″ new snow and water of 1.15″. Snowpack at 82 1/2″ deep. Strong wind that has started to let up a bit, about 8-14 W and gusts to 20. Sky now overcast as cloud cover lifts a bit. Snow stopped around 5:30. New snow is like lead. Temp. range overnight 29 to 30F- nice and warm. Though using the term ‘nice’ with anything to do with current weather is not quite apropos. billy
Snowpack:

Irwin and CB South Corridor Avalanche Obs

CB Avalanche Center2016-17 Observations

Location: Kebler Pass Area
Date of Observation: 02/08/2017
Name: Ian Havlick
Subject: Irwin and CB South Corridor Avalanche Obs
Aspect: North, North East, East
Elevation: 8,600-12,000

Avalanches: Observed:
-two size 1.5 windslabs triggered on E-facing terrain with large explosives 5-12# shots.
– two size 1.5 windslabs on ENE facing Scarp Ridge at 11,600ft, 1-2ft deep
-Size 2.5 windslab on N facing Whetsone in M-Face Bowl, failing below cornice, running over cliff band and triggering secondary slide below ,hard to tell depth, but 2-3ft?
-Handful of Hwy 135 slides, steep, windloaded pockets, 1-2ft deep
Weather: decreasing winds mid morning, snow tapering as well. Sun at times and warming temperatures to 32º.
Snowpack: dramatically less reactive snowpack than Tuesday during storm. very dense, 16% snow, continued light windloading at ridgetop.

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Rumbling collapses on south aspect

CB Avalanche Center2016-17 Observations

Location: Crested Butte Area
Date of Observation: 02/08/2017
Name: Ben Pritchett
Subject: Rumbling collapses on south aspect
Aspect: South East, South, South West
Elevation: 9,000-11,000′

Avalanches: We saw evidence of snowpocalypse avalanching, with severed tree limbs scattered poking out of the snow surface mid track. The start zone for this path was deeply drifted back in by last night’s gusty winds with no surface clues of what did and didn’t slide.
Weather: Storm breaking, with overcast skies becoming broken. Brief waves of graupel throughout the morning. Precip ended at noon.
Snowpack: Numerous rumbling collapses in open (non-treed) slopes. My partner, who backcountry skis 3-5 times a week, commented “that’s more collapsing than I’ve heard all season.” Average snow height ranged from 120-140cm, up to 160cm by 11,000′. Failure layer was the moist 1mm facets below the Feb 6th crust, now burdened with 20-25cm of graupel from this storm. These moist facets were riddled with moist/weak percolation columns extending below the moist 4cm thick Feb 6 crust. The crust was significantly weaker than it would be if were frozen and dry. Today it was marginally supportive on skis and 1F hard. With a good freeze, this snowpack structure will become strong and supportive. Until then, it could be a concern in wind-loaded and very steep / unsupported terrain, or if we get a big load in the near future.

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Upper Cement Creek obs

CB Avalanche Center2016-17 Observations

Location: Cement Creek and Crested Butte Areas
Date of Observation: 02/08/2017
Name: Zach Guy and Evan Ross
Subject: Upper Cement Creek obs
Aspect: East, South East, South West
Elevation: 9000-10500

Avalanches: Decent views of below treeline and some near treeline slopes in Cement Creek Drainage with no signs of avalanche activity. Spotted a few D1 to D1.5 natural wind slabs on easterly slopes along HWY 135 below treeline and what looked like a D2 on a SE aspect of White Mtn above treeline. See photos.
Weather: Felt like an April storm. S2 with periods of S5. Overcast skies began clearing midday. Warm temps. Calm winds at our elevation; some plumes observed off of higher peaks once we got visibility.
Snowpack: 30-40 cm of dense storm snow, appeared to be bonding fairly well to underlying crusts. We observed several crust sandwiches at the storm interface on SW and SE aspects BTL, but they didn’t appear to have concerning facet layers between. There were some rounding 1mm facets below the lowest crust layer (Feb 4th crust). ECTN above the crusts in a wind protected SW slope. Storm snow continued to settle through the day and we saw some rollerball activity in the afternoon.

D2. SE aspect White Mtn.

WSW aspect at 10,500 ft. About 35 cm of dense storm snow over a pair of thin crusts. ECTN 19, BRK just above the crusts. 1mm rounding facets below the lowest crust.

Rollerballs observed on steep E, S, and SW aspects today.

D1 BTL. NE aspect.

D1.5 NE aspect BTL.

 

Irwin Tenure

CB Avalanche Center2016-17 Observations

Location: Kebler Pass Area
Date of Observation: 02/07/2017
Name: Irwin Guides
Subject: Irwin Tenure
Aspect: East, South East, South, South West, West
Elevation: 10,000-12,000

Avalanches: Numerous D1-1.5 windslabs breaking at skis on aggressive ski cuts and shooting cracks up to 30′ across or downslope. No unusual persistent slab behavior observed. Windslabs found on lee and crossloaded terrain features from strong SW winds.
Weather: 8″ storm snow this morning, accumulated to 11″ storm snow. Snowfall rates ranged between 1-2″/hr at times. Winds increased and intensified throughout the day with gusts easily into the 60s at ridgetop. Temperatures rose gradually throughout the day to 27º at study plot (10k) and rose to 21ºF at ridge (12k).
Snowpack: 5″ .5swe during day making storm total 11″ 1.1″swe of heavy dense snow which fell on 2″ of lighter, stellars yesterday. SW winds blowing steady 30-40mph with stronger gusts and creating 2-4′ drifts. Windslabs failing just above widespread suncrusts and windboard. Will continue to monitor new snow and accumulation and development of more widespread storm slabs overnight.

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Shallow storm slabs

CB Avalanche Center2016-17 Observations

Location: Kebler Pass Area
Date of Observation: 02/07/2017
Name: Evan Ross, Alex Bannas
Subject: Shallow storm slabs
Aspect: North, North East
Elevation: 10,000-11,400

Avalanches: Touchy storm slabs. Some incredibly small roller balls/sluffs would fracture slopes within the storm snow. Some of these fractures would propagate through the terrain and pop shallow storm slabs on steeper slopes. Most triggered storm slabs where D1.5’s. where the terrain was larger with more relief, these slabs would accumulate more snow and become D2’s.

Several of these crowns where far enough below ridgelines that the problem wasn’t specific to wind loading.

Lots of natural small sluffing in steep terrain. Watched at least one of these step down into a wider storm slab.
Weather: Obscured sky. Warm near freezing temps. S2 snowfall through the day. Winds light to moderate out of the south as the wrapped around the big massif of East Beckwith.
Snowpack: About 30cm of new snow on the old snow interface in the mid afternoon. New snow was graupely and somewhat dense fist to fist+ snow. Storm slabs were failing in the upper 10 to 15cm of new snow with a bit of a density change of F+ over F snow. Old snow surface didn’t appear to be particularly concerning. Not much for NFS at this new/old interface. Start zones in this area had about 260cm of snow and had seen previous avalanching. Measured one area that hadn’t previously avalanched at 370cm. Also on this deeper slope, no CT result below the old snow interface in a 130cm deep pit. While setting up a DT test, found the 1/19 SH down 100cm, sandwiched between 1f+ hard snow.

Ski cuts produced shooting cracks on slopes under 35 degrees.

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Ski cuts and stomping released shallow storm slabs on slopes over 35 degrees. Some of these storm slabs gouged down to the old snow interface entraining more mass that produced D2 avalanches.

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Wind slabs and persistent slabs on Schuylkill Ridge

CB Avalanche Center2016-17 Observations

Location: Paradise Divide Area
Date of Observation: 02/07/2017
Name: Zach Guy
Subject: Wind slabs and persistent slabs on Schuylkill Ridge
Aspect: North East, East, South East, South
Elevation: 9,000- 11,100 ft.

Avalanches: Ski cut a small windslab on a crossloaded SE slope NTL. It was about 8-12″ deep, and ran on the melt-freeze crust interface, small in size. SS-ASc-R1-D1-I. See photos.
Weather: Surprisingly calm winds, but evidence of previous wind transport from the SW at ridgeline. S-1 to S1, snow in the morning and graupel in the afternoon. About 5 cm accumulated from 12 p.m. to 4 pm. Overcast skies and relatively warm temperatures.
Snowpack: Storm total below treeline was 25 cm by the end of the day. No signs of storm slab instabilities below treeline on sunny or shady aspects, but as we approached treeline, slabs became denser and more wind affected, with drifts up to 35cm thick. Minor cracking on NE aspects, where the storm snow was on hard wind board, and moderate cracking on SE aspects, where the storm snow was on a stack of melt-freeze crusts (Feb 4 crust was 3-6 cm thick, pencil hard, and Feb 6 crust was 2 cm thick and 4F to 1F hard, with a soft layer between). On a NE aspect BTL, one pit produced moderate, propagating results, 53 cm deep on the 1/19 surface hoar, below a 4F+ slab. (ECTP16, SC). No signs of instability observed on this layer.

Skier triggered wind slab.  SE aspect NTL
Cracking snow near treeline
ECTP16, SC on 1/19 SH, below a 53 cm, 4F+ slab.  NE aspect BTL.

Buried surface hoar- Coney’s

CB Avalanche Center2016-17 Observations

Location: Crested Butte Area
Date of Observation: 02/06/2017
Name: K and K Rohrig
Subject: Buried surface hoar- Coney’s
Aspect: North East
Elevation: 10,800′

Avalanches:
Weather: Obscured, sporadic snow with periods of intense snow
Light S winds
Snowpack: Top of Convex Corner on Coney’s, just below the ridge line, < 30 degrees
250 cm HS
5-7 cm new snow
CTM x 2 SP, ECTP14, down 50 cm, failed on 3-5 mm surface hoar
We found another non reactive layer that “propagated” the full 90 cm when we pulled our ECT column into the pit. This is a layer of decomposing graupel down 20 cm. No cracking, no whomphing, no other signs of instability.